Definitions Part 2 Flashcards
1
Q
Binocular Rivalry
A
A situation in which one image is presented to the left eye and a different image is presented to the right eye, and perception alternates back and forth between the two images.
2
Q
Border ownership
A
When two areas share a border, as occurs in figure–ground displays, the border is usually perceived as belonging to the figure.
3
Q
Figure
A
When an object is seen as separate from the background (the “ground”), it is called a figure. See also figure–ground segregation.
4
Q
Figure-ground segregation
A
The perceptual separation of an object from its background
5
Q
Gestalt Psychology
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An approach to psychology that developed as a reaction to structuralism. The Gestalt approach proposes principles of perceptual organization and figure–ground segregation and states that “the whole is different than the sum of its parts.”
6
Q
Gist of a scene
A
General description of a scene. People can identify most scenes after viewing them for only a fraction of a second, as when they flip rapidly from one TV channel to another. It takes longer to identify the details within the scene.
7
Q
Global image features
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Information that may enable observers to rapidly perceive the gist of a scene. Features associated with specific types of scenes include degree of naturalness, degree of openness, degree of roughness, degree of expansion, and color.
8
Q
Ground
A
In object perception, the background is called the ground.
9
Q
Grouping
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In perceptual organization, the process by which visual events are “put together” into units or objects.
10
Q
Illusory Contour
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Contour that is perceived even though it is not present in the physical stimulus.
11
Q
Inverse projection problem
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The idea that a particular image on the retina could have been caused by an infinite number of different objects. This means that the retinal image does not unambiguously specify a stimulus.
12
Q
Light from above assumption
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The assumption that light usually comes from above, which influences our perception of form in some situations.
13
Q
Likelihood principle
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The idea proposed by Helmholtz that we perceive the object that is most likely to have caused the pattern of stimuli we have received.
14
Q
Organizing principles
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In Gestalt psychology, the rules that determine how elements in a scene become grouped together.
15
Q
Perceptual organization
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The process by which small elements become perceptually grouped into larger objects.
16
Q
Perceptual segregation
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Perceptual organization in which one object is seen as separate from other objects.
17
Q
Persistence of vision
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A phenomenon in which perception of any stimulus persists for about 250 ms after the stimulus is physically terminated.
18
Q
Physical regularities
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Regularly occurring physical properties of the environment. For example, there are more vertical and horizontal orientations in the environment than oblique (angled) orientations.
19
Q
Principle of common fate
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A Gestalt principle of perceptual organization that states that things that are moving in the same direction appear to be grouped together.
20
Q
Principle of common region
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A modern Gestalt principle that states that elements that are within the same region of space appear to be grouped together.
21
Q
Principle of good continuation
A
A Gestalt principle of perceptual organization that states that points that, when connected, result in straight or smoothly curving lines are seen as belonging together, and that lines tend to be seen in such a way as to follow the smoothest path.
22
Q
Principle of good figure
A
A Gestalt principle of perceptual organization that states that every stimulus pattern is seen in such a way that the resulting structure is as simple as possible. Also called the principle of pragnanz or the principle of simplicity.
23
Q
Principle of pragnaz
A
A Gestalt principle of perceptual organization that states that every stimulus pattern is seen in such a way that the resulting structure is as simple as possible. Also called the principle of good figure or the principle of simplicity.
24
Q
Principle of proximity
A
A Gestalt principle of perceptual organization that states that things that are near to each other appear to be grouped together. Also called the law of nearness.
25
Principle of similarity
A Gestalt principle stating that similar things appear to be grouped together.
26
Principle of simplicity
A Gestalt principle of perceptual organization that states that every stimulus pattern is seen in such a way that the resulting structure is as simple as possible. Also called the principle of good figure or the principle of pragnanz.
27
Principle of uniform connectedness
A modern Gestalt principle that states that connected regions of a visual stimulus are perceived as a single unit.
28
Regularities in the environment
Characteristics of the environment that occur regularly and in many different situations.
29
Reversible figure-ground
A figure–ground pattern that perceptually reverses as it is viewed, so that the figure becomes the ground and the ground becomes the figure. The best-known reversible figure–ground pattern is Rubin’s vase–face pattern.
30
Scene
A view of a real-world environment that contains (a) background elements and (b) multiple objects that are organized in a meaningful way relative to each other and the background.
31
Segregation
The process of separating one area or object from another.
32
Semantic encoding
A method for analyzing the patterns of voxel activation recorded from visual areas of an observer’s brain, based on the relationship between voxel activation and the meaning or category of a scene.
33
Semantic regularities
Characteristics associated with the functions associated with different types of scenes. These characteristics are learned from experience. For example, most people are aware of the kinds of activities and objects that are usually associated with kitchens.
34
Sensations
Elementary elements that, according to the structuralists, combine to create perceptions.
35
Structural encoding
A method for analyzing the patterns of voxel activation recorded from visual areas of an observer’s brain, based on the relationship between voxel activation and structural characteristics of a scene, such as lines, contrasts, shapes, and textures.
36
Structuralism
According to structuralism, a number of sensations (represented by the dots) add up to create our perception of the face. The approach to psychology, prominent in the late 19th and early 20th centuries, that postulated that perceptions result from the summation of many elementary sensations. The Gestalt approach to perception was, in part, a reaction to structuralism.
37
Theory of unconscious inference
The idea proposed by Helmholtz that some of our perceptions are the result of unconscious assumptions that we make about the environment.
38
Viewpoint invariance
The condition in which object properties don’t change when viewed from different angles. Responsible for our ability to recognize objects when viewed from different angles.
39
Visual masking stimulus
A visual pattern that, when presented immediately after a visual stimulus, decreases a person’s ability to perceive the stimulus. This stops the persistence of vision and therefore limits the effective duration of the stimulus.
40
Attention
The process of focusing on some objects while ignoring others. Attention can enhance the processing of the attended object.
41
Attentional capture
Occurs when stimulus salience causes an involuntary shift of attention. For example, attention can be captured by movement.
42
Autism
A serious developmental disorder in which one of the major symptoms is the withdrawal of contact from other people. People with autism typically do not make eye contact with others and have difficulty telling what emotions others are experiencing in social situations.
43
Balint's syndrome
A condition resulting from damage to a person’s parietal lobe. One characteristic of this syndrome is an inability to focus attention on individual objects.
44
Binding
The process by which features such as color, form, motion, and location are combined to create our perception of a coherent object. Binding can also occur across senses, as when sound and vision are associated with the same object.
45
Binding problem
The problem of how neural activity in many separated areas in the brain is combined to create a perception of a coherent object.
46
Change blindness
Difficulty in detecting differences between two visual stimuli that are presented one after another, often with a short blank stimulus interposed between them. Also occurs when part of a stimulus is changed very slowly.
47
Conjunction search
A visual search task in which it is necessary to search for a combination (or conjunction) of two or more features on the same stimulus to find the target. An example of a conjunction search would be looking for a horizontal green line among vertical green lines and horizontal red lines.
48
Covert Attention
Attention without looking. Seeing something “out of the corner of your eye” is an example of covert attention.
49
Dishabituation
An increase in looking time that occurs when a stimulus is changed. This response is used in testing infants to see whether they can differentiate two stimuli.
50
Dual-task procedure
An experimental procedure in which subjects are required to carry out simultaneously a central task that demands attention and a peripheral task that involves making a decision about the contents of a scene.
51
Feature integration theory
A theory proposed by Treisman to explain how an object is broken down into features and how these features are recombined to result in a perception of the object.
52
Feature search
A visual search task in which a person can find a target by searching for only one feature. An example would be looking for a horizontal green line among vertical green lines.
53
Fixation
The brief pause of the eye that occurs between eye movements as a person scans a scene.
54
Focused attention stage (of perceptual processing)
The stage of processing in feature integration theory in which the features are combined. According to Treisman, this stage requires focused attention.
55
Habituation
Paying less attention to the same stimulus that is presented repeatedly. For example, infants look at a stimulus less and less on each successive trial.
56
High-load task
Task that involves more processing resources and that therefore uses more of a person’s perceptual capacity.
57
Illusory conjunction
Illusory combination of features that are perceived when stimuli containing a number of features are presented briefly and under conditions in which focused attention is difficult. For example, presenting a red square and a blue triangle could potentially create the perception of a red triangle.
58
Inattentional blindness
A situation in which a stimulus that is not attended is not perceived, even though the person is looking directly at it.
59
Load theory of attention
Lavie’s proposal that the amount of perceptual capacity that remains as a person is carrying out a task determines how well the person can avoid being distracted by task-irrelevant stimuli. If a person’s perceptual load is close to perceptual capacity, the person is less likely to be distracted by task-irrelevant stimuli.
60
Overt attention
Attention that involves looking directly at the attended object.
61
Perceptual capacity
The resources a person has for carrying out perceptual tasks.
62
Perceptual completion
The perception of an object as extending behind occluding objects.
63
Perceptual load
The amount of a person’s perceptual capacity needed to carry out a particular perceptual task.
64
Preattentive stage (of perceptual processing)
An automatic and rapid stage of processing, proposed by Treisman’s feature integration theory, during which a stimulus is decomposed into individual features.
65
Precueing
A procedure in which a cue stimulus is presented to direct an observer’s attention to a specific location where a test stimulus is likely to be presented. This procedure was used by Posner to show that attention enhances the processing of a stimulus presented at the cued location.
66
Saccadic eye movement
Rapid eye movement between fixations that occurs when scanning a scene.
67
Saliency Map
A “map” of a visual display that takes into account characteristics of the display such as color, contrast, and orientation that are associated with capturing attention.
68
Same-object advantage
The faster responding that occurs when enhancement spreads within an object. Faster reaction times occur when a target is located within the object that is receiving the subject’s attention, even if the subject is looking at another place within the object.
69
Scene schema
An observer’s knowledge about what is contained in typical scenes. An observer’s attention is affected by knowledge of what is usually found in the scene.
70
Scene statistics
The probability of various things occurring in the environment.
71
Stimulus salience
Characteristics such as bright colors, high contrast, and highly visible orientations that cause stimuli to stand out and therefore attract attention.
72
Task-irrelevant stimuli
Stimuli that do not provide information relevant to the task at hand.
73
Visual scanning
Moving the eyes to focus attention on different locations on objects or in scenes.
74
Visual search
A procedure in which a person’s task is to find a particular element in a display that contains a number of elements.
75
Affordance
The information specified by a stimulus pattern that indicates how the stimulus can be used. An example of an affordance would be seeing a chair as something to sit on or a flight of stairs as something to climb.
76
Audiovisual mirror neuron
Neuron that responds to actions that produce sounds. These neurons respond when a monkey performs a hand action and when it hears the sound associated with this action.
77
Ecological approach to perception
This approach focuses on specifying the information in the environment that is used for perception, emphasizing the study of moving observers to determine how their movement results in perceptual information that both creates perception and guides further movement.
78
Focus of expansion FOE
The point in the flow pattern caused by observer movement in which there is no expansion. According to J. J. Gibson, the focus of expansion always remains centered on the observer’s destination.
79
Gradient of flow
In an optic flow pattern, a gradient is created by movement of an observer through the environment. The “gradient” refers to the fact that the optic flow is rapid in the foreground and becomes slower as distance from the observer increases.
80
Invariant information
Environmental properties that do not change as the observer moves relative to an object or scene. For example, the spacing, or texture, of the elements in a texture gradient does not change as the observer moves on the gradient. The texture of the gradient therefore supplies invariant information for depth perception.
81
Landmarks
Objects on a route that serve as cues to indicate where to turn; a source of information for wayfinding.
82
Mirror neuron
Neuron in the premotor area of the monkey’s cortex that responds when the monkey grasps an object and also when the monkey observes someone else (another monkey or the experimenter) grasping the object. There is also evidence for mirror neuron-like activity in the human brain.
83
Optic ataxia
A condition in which individuals with parietal lobe damage have trouble pointing to visual stimuli.
84
Optic flow
The flow of stimuli in the environment that occurs when an observer moves relative to the environment. Forward movement causes an expanding optic flow, whereas backward movement causes a contracting optic flow. Some researchers use the term optic flow field to refer to this flow.
85
Parietal reach region PRR
A network of areas in the parietal cortex that contains neurons that are involved in reaching behavior.
86
Self produced information
Generally, environmental information that is produced by actions of the observer. An example is optic flow, which occurs as a result of a person’s movement and which, in turn, provides information that can be used to guide that movement.
87
Visual direction strategy
A strategy used by moving observers to reach a destination by keeping their body oriented toward the target.
88
Visuomotor grip cell
A neuron that initially responds when a specific object is seen, and then also responds as a hand grasps the same object.
89
Wayfinding
The process of navigating through the environment. Wayfinding involves perceiving objects in the environment, remembering objects and their relation to the overall scene, and knowing when to turn and in what direction.
90
Akinetopsia
A condition in which damage to an area of the cortex involved in motion perception causes blindness to motion.
91
Aperature problem
Occurs when only a portion of a moving stimulus can be seen, as when the stimulus is viewed through a narrow aperture. This can result in misleading information about the direction in which the stimulus is moving.
92
Apparent motion
An illusion of movement that occurs when two objects separated in space are presented rapidly, one after another, separated by a brief time interval.
93
Attentional capture
Occurs when stimulus salience causes an involuntary shift of attention. For example, attention can be captured by movement.
94
Biological motion
Motion produced by biological organisms. Most of the experiments on biological motion have used walking humans with lights attached to their joints and limbs as stimuli.
95
Coherence
In research on movement perception in which arrays of moving dots are used as stimuli, the degree of correlation between the direction of the moving dots. Zero percent coherence means all of the dots are moving independently; 100 percent coherence means all of the dots are moving in the same direction.
96
Comparator
A structure hypothesized by the corollary discharge theory of movement perception. The corollary discharge signal and the sensory movement signal meet at the comparator to determine whether movement will be perceived.
97
Corollary discharge signal
A copy of the motor signal that is sent to the eye muscles to cause movement of the eye. The copy is sent to the hypothetical comparator of corollary discharge theory.
98
Corollary discharge theory
The theory that explains motion perception as being determined both by movement of the image on the retina and by signals that indicate movement of the eyes.
99
Event
A segment of time at a particular location that is perceived by observers to have a beginning and an ending.
100
Event boundary
The point in time when one event ends and another begins.
101
Global optic flow
Information for movement that occurs when all elements in a scene move. The perception of global optic flow indicates that it is the observer that is moving and not the scene.
102
Illusory motion
Perception of motion when there actually is none.
103
Image displacement signal
In corollary discharge theory, the signal that occurs when an image moves across the visual receptors.
104
Implied motion
When a still picture depicts an action that involves motion, so that an observer could potentially extend the action depicted in the picture in his or her mind based on what will most likely happen next.
105
Induced motion
The illusory movement of one object that is caused by the movement of another object that is nearby.
106
Local disturbance in the optic array
Occurs when one object moves relative to the environment, so that the stationary background is covered and uncovered by the moving object. This local disturbance indicates that the object is moving relative to the environment.
107
Microstimulation
A procedure in which a small electrode is inserted into the cortex and an electrical current passed through the electrode activates neurons near the tip of the electrode. This procedure has been used to determine how activating specific groups of neurons affects perception.
108
Motion aftereffect
An illusion that occurs after a person views a moving stimulus and then sees movement in the opposite direction when viewing a stationary stimulus immediately afterward.
109
Motor signal MS
In corollary discharge theory, the signal that is sent to the eye muscles when the observer moves or tries to move his or her eyes.
110
Optic array
The structured pattern of light created by the presence of objects, surfaces, and textures in the environment.
111
Point-light walker
A biological motion stimulus created by placing lights at a number of places on a person’s body and having an observer view the moving-light stimulus that results as the person moves in the dark.
112
Real motion
The physical movement of a stimulus
113
Real motion neuron
Neuron in the monkey’s cortex that responds when movement of an image across the retina is caused by movement of a stimulus, but does not respond when movement across the retina is caused by movement of the eyes.
114
Reichardt detector
A neural circuit that results in neurons firing to movement in one direction. Excitation and inhibition are arranged so that movement in one direction creates inhibition that reduces or eliminates neural responding, whereas movement in the opposite direction creates excitation that enhances neural responding.
115
Representational momentum
Occurs when motion depicted in a still picture continues in an observer’s mind.
116
Shortest path constraint
In the perception of apparent motion, the principle that apparent movement tends to occur along the shortest path between two stimuli.
117
Waterfall illusion
An aftereffect of movement that occurs after viewing a stimulus moving in one direction, such as a waterfall. Viewing the waterfall makes other objects appear to move in the opposite direction.
118
Achromatic colour
Color without hue. White, black, and all the grays between these two extremes are achromatic colors.
119
Additive colour mixture
The creation of colors that occurs when lights of different colors are superimposed.
120
Anomalous trichromat
A person who needs to mix a minimum of three wavelengths to match any other wavelength in the spectrum but mixes these wavelengths in different proportions from a trichromat.
121
Cerebral anchromatopsia
A loss of color vision caused by damage to the cortex.
122
Chromatic adaptation
Exposure to light in a specific part of the visible spectrum. This adaptation can cause a decrease in sensitivity to light from the area of the spectrum that was presented during adaptation.
123
Chromatic colour
Color with hue, such as blue, yellow, red, or green.
124
Colour blindness
A condition in which a person perceives no chromatic color. This can be caused by absent or malfunctioning cone receptors or by cortical damage.
125
Color constancy
The effect in which the perception of an object’s hue remains constant even when the wavelength distribution of the illumination is changed. Partial color constancy occurs when our perception of hue changes a little when the illumination changes, though not as much as we might expect from the change in the wavelengths of light reaching the eye.
126
Colour deficiency
People with this condition (sometimes incorrectly called color blindness) see fewer colors than people with normal color vision and need to mix fewer wavelengths to match any other wavelength in the spectrum.
127
Colour matching experiment
A procedure in which observers are asked to match the color in one field by mixing two or more lights in another field.
128
Desaturated
Low saturation in chromatic colors as would occur when white is added to a color. For example, pink is not as saturated as red.
129
Deuteranopia
A form of red–green color dichromatism caused by lack of the middle-wavelength cone pigment.
130
Dichromat
A person who has a form of color deficiency. Dichromats can match any wavelength in the spectrum by mixing two other wavelengths. Deuteranopes, protanopes, and tritanopes are all dichromats.
131
Double-opponent neurons
Neurons that have receptive fields in which stimulation of one part of the receptive field causes an excitatory response to wavelengths in one area of the spectrum and an inhibitory response to wavelengths in another area of the spectrum, and stimulation of an adjacent part of the receptive field causes the opposite response. An example of double-opponent responding is when the response of one part of a receptive field is L+ M- and the response of an adjacent part is L- M+.
132
Hue
The experience of a chromatic color such as red, green, yellow, or blue or combinations of these colors.
133
Illumination edge
The border between two areas created by different light intensities in the two areas.
134
Ishihara plate
A display of colored dots used to test for the presence of color deficiency. The dots are colored so that people with normal (trichromatic) color vision can perceive numbers in the plate, but people with color deficiency cannot perceive these numbers or perceive different numbers than someone with trichromatic vision.
135
Lightness
The perception of shades ranging from white to grey to black
136
Lightness constancy
The constancy of our perception of an object’s lightness under different intensities of illumination.
137
Memory colour
The idea that an object’s characteristic color influences our perception of that object’s color.
138
Metamerism
The situation in which two physically different stimuli are perceptually identical. In vision, this refers to two lights with different wavelength distributions that are perceived as having the same color.
139
Metamers
Two lights that have different wavelength distributions but are perceptually identical.
140
Monochromat
A person who is completely color-blind and therefore sees everything as black, white, or shades of gray. A monochromat can match any wavelength in the spectrum by adjusting the intensity of any other wavelength. Monochromats generally have only one type of functioning receptors, usually rods.
141
Neutral point
The wavelength at which a dichromat perceives gray.
142
Opponent neuron
A neuron that has an excitatory response to wavelengths in one part of the spectrum and an inhibitory response to wavelengths in the other part of the spectrum.
143
Opponent-process theory of colour vision
A theory originally proposed by Hering, which claimed that our perception of color is determined by the activity of two opponent mechanisms: a blue–yellow mechanism and a red–green mechanism. The responses to the two colors in each mechanism oppose each other, one being an excitatory response and the other an inhibitory response. In addition, this theory also includes a black–white mechanism, which is concerned with the perception of brightness.
144
Partial colour constancy
A type of color constancy that occurs when changing an object’s illumination causes a change in perception of the object’s hue, but less change than would be expected based on the change in the wavelengths of light reaching the eye. Note that in complete color constancy, changing an object’s illumination causes no change in the object’s hue.
145
Penumbra
The fuzzy border at the edge of a shadow.
146
Protanopia
A form of red–green dichromatism caused by a lack of the long-wavelength cone pigment.
147
Ratio principle
A principle stating that two areas that reflect different amounts of light will have the same perceived lightness if the ratios of their intensities to the intensities of their surroundings are the same.
148
Reflectance
The percentage of light reflected from a surface.
149
Reflectance curve
A plot showing the percentage of light reflected from an object versus wavelength.
150
Reflectance edge
An edge between two areas where the reflectance of two surfaces changes.
151
Saturation (colour)
The relative amount of whiteness in a chromatic color. The less whiteness a color contains, the more saturated it is.
152
Selective reflection
When an object reflects some wavelengths of the spectrum more than others.
153
Selective transmission
When some wavelengths pass through visually transparent objects or substances and others do not. Selective transmission is associated with the perception of chromatic color.
154
Simultaneous colour contrast
The effect that occurs when surrounding one color with another changes the appearance of the surrounded color. Occurs for chromatic and achromatic stimuli.
155
Single-opponent neuron
Neurons that increase firing to long wavelengths presented to the center of the receptive field and decrease firing to short wavelengths presented to the surround (or vice versa).
156
Subtractive colour mixture
The creation of colors that occurs when paints of different colors are mixed together.
157
Trichromat
A person with normal color vision. Trichromats can match any wavelength in the spectrum by mixing three other wavelengths in various proportions.
158
Trichromatic theory of colour vision
A theory proposing that our perception of color is determined by the ratio of activity in three receptor mechanisms with different spectral sensitivities.
159
Tritanopia
A form of dichromatism thought to be caused by a lack of the short-wavelength cone pigment.
160
Unilateral dichromat
A person who has dichromatic vision in one eye and trichromatic vision in the other eye. People with this condition (which is extremely rare) have been tested to determine what colors a dichromats perceive by asking them to compare the perceptions they experience with their dichromatic eye and their trichromatic eye.
161
Young-Helmholtz theory of colour vision
A theory proposing that our perception of color is determined by the ratio of activity in three receptor mechanisms with different spectral sensitivities.
162
Absolute disparity
The visual angle between the images of an object on the two retinas. When images of an object fall on corresponding points, the angle of disparity is zero. When images fall on noncorresponding points, the angle of disparity indicates the degree of noncorrespondence.
163
Accretion
A cue that provides information about the relative depth of two surfaces. Occurs when the farther object is uncovered by the nearer object due to sideways movement of an observer relative to the objects.
164
Active method (3D TV)
A method used to create 3-D television images. The active method alternates the left-eye and right-eye images on the screen 30 or more times a second. This method is called active because the viewing glasses have a shutter system that is synchronized with the alternating images on the TV screen.
165
Ames room
A distorted room, first built by Adelbert Ames, that creates an erroneous perception of the sizes of people in the room. The room is constructed so that two people at the far wall of the room appear to stand at the same distance from an observer. In actuality, one of the people is much farther away than the other.
166
Angle of disparity
The visual angle between the images of an object on the two retinas. When images of an object fall on corresponding points, the angle of disparity is zero. When images fall on noncorresponding points, the angle of disparity indicates the degree of noncorrespondence.
167
Angular size contrast theory
An explanation of the moon illusion that states that the perceived size of the moon is determined by the sizes of the objects that surround it. According to this idea, the moon appears small when it is surrounded by large objects, such as the expanse of the sky when the moon is overhead.
168
Apparent distance theory
An explanation of the moon illusion that is based on the idea that the horizon moon, which is viewed across the filled space of the terrain, should appear farther away than the zenith moon, which is viewed through the empty space of the sky. This theory states that because the horizon and zenith moons have the same visual angle but are perceived to be at different distances, the farther appearing horizon moon should appear larger.
169
Atmospheric perspective
A depth cue. Objects that are farther away look more blurred and bluer than objects that are closer because we must look through more air and particles to see them.
170
Binocular depth cell
A neuron in the visual cortex that responds best to stimuli that fall on points separated by a specific degree of disparity on the two retinas. Also called a disparity-selective cell.
171
Binocular disparity
Occurs when the retinal images of an object fall on disparate points on the two retinas.
172
Binocular fixate
Directing the two foveas to exactly the same spot.
173
Conflicting cues theory
A theory of visual illusions proposed by R. H. Day, which states that our perception of line length depends on an integration of the actual line length and the overall figure length.
174
Correspondence problem
The problem faced by the visual system, which must determine which parts of the images in the left and right eyes correspond to one another. Another way of stating the problem is: How does the visual system match up the images in the two eyes? This matching of the images is involved in determining depth perception using the cue of binocular disparity.
175
Corresponding retinal points
The points on each retina that would overlap if one retina were slid on top of the other. Receptors at corresponding points send their signals to the same location in the brain.
176
Cue approach to depth perception
The approach to explaining depth perception that identifies information in the retinal image, and also information provided by aiming and focusing the eyes on an object that is correlated with depth in the scene. Some of the depth cues that have been identified are overlap, relative height, relative size, atmospheric perspective, convergence, and accommodation.
177
Deletion
A cue that provides information about the relative depth of two surfaces. Deletion occurs when a farther object is covered by a nearer object due to sideways movement of an observer relative to the objects.
178
Disparity tuning curve
A plot of a neuron’s response versus the degree of disparity of a visual stimulus. The disparity to which a neuron responds best is an important property of disparity-selective cells, which are also called binocular depth cells.
179
Disparity-selective cell
A neuron in the visual cortex that responds best to stimuli that fall on points separated by a specific degree of disparity on the two retinas. Also called a binocular depth cell.
180
Echolocation
Locating objects by sending out high-frequency pulses and sensing the echo created when these pulses are reflected from objects in the environment. Echolocation is used by bats and dolphins.
181
Emmert's law
A law stating that the size of an afterimage depends on the distance of the surface against which the afterimage is viewed. The farther away the surface, the larger the afterimage appears.
182
Familiar size
A depth cue in which judgment of distance is based on knowledge of the sizes of objects. Epstein’s coin experiment illustrated the operation of the cue of familiar size by showing that the relative sizes of the coins influenced perception of the coins’ distances.
183
Frontal eyes
Eyes located in front of the head, so the views of the two eyes overlap.
184
Horopter
An imaginary surface that passes through the point of fixation. Images caused by a visual stimulus on this surface fall on corresponding points on the two retinas.
185
Lateral eyes
Eyes located on opposite sides of an animal’s head, so the views of the two eyes do not overlap or overlap only slightly, as in the pigeon and rabbit.
186
Lenticular projection
A method used to create 3-D television images. The screen is coated with a film containing two sets of lenses, which results in different images reaching the left and right eyes. An example being those postcards that show different images depending on the angle held.
187
Muller-Lyer illusion
An illusion in which two lines of equal length appear to be of different lengths because of the addition of “fins’’ to the ends of the lines.
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Misapplied size constancy scaling
A principle, proposed by Richard Gregory, that when mechanisms that help maintain size constancy in the three-dimensional world are applied to two-dimensional pictures, an illusion of size sometimes results.
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Monocular cue
Depth cue—such as overlap, relative size, relative height, familiar size, linear perspective, movement parallax, and accommodation—that can work when we use only one eye.
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Moon illusion
An illusion in which the moon appears to be larger when it is on or near the horizon than when it is high in the sky.
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Motion parallax
A depth cue. As an observer moves, nearby objects appear to move rapidly across the visual field, whereas far objects appear to move more slowly.
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Noncorresponding points
Two points, one on each retina, that would not overlap if the retinas were slid onto each other. Also called disparate points.
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Occlusion
Depth cue in which one object hides or partially hides another object from view, causing the hidden object to be perceived as being farther away. A monocular depth cue.
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Oculomotor cue
Depth cue that depends on our ability to sense the position of our eyes and the tension in our eye muscles. Accommodation and convergence are oculomotor cues.
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Passive method (3DTV)
A method used to create 3-D television images. Polarized light is used to create left and right images—one image is polarized so its vibration is vertical, and the other is polarized so its vibration is horizontal. The TV is viewed through polarizing lenses, which let vertically polarized light into one eye and horizontally polarized light into the other eye, creating the disparity that results in three-dimensional perception.
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Perspective convergence
The perception that parallel lines in the distance converge as distance increases.
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Pictoral cue
Monocular depth cue, such as overlap, relative height, and relative size, that can be depicted in pictures.
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Ponzo illusion
An illusion of size in which two objects of equal size that are positioned between two converging lines appear to be different in size. Also called the railroad track illusion.
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Random dot stereogram
A pair of stereoscopic images made up of random dots. When one section of this pattern is shifted slightly in one direction, the resulting disparity causes the shifted section to appear above or below the rest of the pattern when the patterns are viewed in a stereoscope.
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Relative disparity
The difference between two objects’ absolute disparities.
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Relative height
A monocular depth cue. Objects that have bases below the horizon appear to be farther away when they are higher in the field of view. Objects that have bases above the horizon appear to be farther away when they are lower in the field of view.
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Relative size
A cue for depth perception. When two objects are of equal size, the one that is farther away will take up less of the field of view.
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Size constancy
Occurs when the size of an object is perceived to remain the same even when it is viewed from different distances
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Size distance scaling
A hypothesized mechanism that helps maintain size constancy by taking an object’s perceived distance into account. According to this mechanism, an object’s perceived size, S, is determined by multiplying the size of the retinal image, R, times the object’s perceived distance, D.
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Stereopsis
The impression of depth that results from binocular disparity—the difference in the position of images of the same object on the retinas of the two eyes.
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Stereoscope
A device that presents pictures to the left and the right eyes so that the binocular disparity a person would experience when viewing an actual scene is duplicated. The result is a convincing illusion of depth.
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Stereoscopic depth perception
The perception of depth that is created by input from both eyes.
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Stereoscopic vision
Two-eyed depth perception involving mechanisms that take into account differences in the images formed on the left and right eyes.
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Strabismus
Misalignment of the eyes, such as crossed-eyes or walleyes (outward looking eyes), in which the visual system suppresses vision in one of the eyes to avoid double vision, so the person sees the world with only one eye at a time.
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Texture gradient
The visual pattern formed by a regularly textured surface that extends away from the observer. This pattern provides information for distance because the elements in a texture gradient appear smaller as distance from the observer increases.
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Visual angle
The angle of an object relative to an observer’s eyes. This angle can be determined by extending two lines from the eye—one to one end of an object and the other to the other end of the object. Because an object’s visual angle is always determined relative to an observer, its visual angle changes as the distance between the object and the observer changes.
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Acoustic prism
The way the cochlea separates frequencies entering the ear to create activity at different places along the basilar membrane.
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Amplitude
In the case of a repeating sound wave, such as the sine wave of a pure tone, amplitude represents the pressure difference between atmospheric pressure and the maximum pressure of the wave.
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Apex of the cochlea
The end of the cochlea farthest from the middle ear.
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Attack
The buildup of sound energy that occurs at the beginning of a tone.
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Audibility curve
A curve that indicates the sound pressure level (SPL) at threshold for frequencies across the audible spectrum.
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Auditory canal
The canal through which air vibrations travel from the environment to the tympanic membrane.
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Auditory response area
The psychophysically measured area that defines the frequencies and sound pressure levels over which hearing functions. This area extends between the audibility curve and the curve for the threshold of feeling.
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Base of the cochlea
The part of the cochlea nearest the middle ear.
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Basilar membrane
A membrane that stretches the length of the cochlea and controls the vibration of the cochlear partition.
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Characteristic frequency
The frequency at which a neuron in the auditory system has its lowest threshold.
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Cilia
Fine hairs that protrude from the inner and outer hair cells of the auditory system. Bending the cilia of the inner hair cells leads to transduction.
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Cochlea
The snail-shaped, liquid-filled structure that contains the structures of the inner ear, the most important of which are the basilar membrane, the tectorial membrane, and the hair cells.
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Cochlear amplifier
Expansion and contraction of the outer hair cells in response to sound sharpens the movement of the basilar membrane to specific frequencies. This amplifying effect plays an important role in determining the frequency selectivity of auditory nerve fibers.
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Cochlear implant
A device in which electrodes are inserted into the cochlea to create hearing by electrically stimulating the auditory nerve fibers. This device is used to restore hearing in people who have lost their hearing because of damaged hair cells.
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Cochlear partition
A partition in the cochlea, extending almost its full length, that separates the scala tympani and the scala vestibuli. The organ of Corti, which contains the hair cells, is part of the cochlear partition.
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Decay
The decrease in the sound signal that occurs at the end of a tone.
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Decibel dB
A unit that indicates the pressure of a sound stimulus relative to a reference pressure: dB=20 log (p/po) where p is the pressure of the tone and po is the reference pressure.
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Eardrum
Another term for the tympanic membrane, the membrane located at the end of the auditory canal that vibrates in response to pressure changes. This vibration is transmitted to the bones of the middle ear.
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Effect of the missing fundamental
Removing the fundamental frequency and other lower harmonies from a musical tone does not change the tone’s pitch.
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Equal loudness curve
A curve that indicates the sound pressure levels that result in a perception of the same loudness at frequencies across the audible spectrum.
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First harmonic
A pure tone with frequency equal to the fundamental frequency of a complex tone.
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Frequency
The number of times per second that pressure changes of a sound stimulus repeat. Frequency is measured in Hertz, where 1 Hertz is one cycle per second.
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Frequency spectrum
A plot that indicates the amplitudes of the various harmonics that make up a complex tone. Each harmonic is indicated by a line that is positioned along the frequency axis, with the height of the line indicating the amplitude of the harmonic.
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Frequency tuning curve
Curve relating frequency and the threshold intensity for activating an auditory neuron.
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Fundamental
A pure tone with frequency equal to the fundamental frequency of a complex tone. See also fundamental frequency.
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Fundamental frequency
The first harmonic of a complex tone; usually the lowest frequency in the frequency spectrum of a complex tone. The tone’s other components, called higher harmonics, have frequencies that are multiples of the fundamental frequency.
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Hair cell
Neuron in the cochlea that contains small hairs, or cilia, that are displaced by vibration of the basilar membrane and fluids inside the inner ear. There are two kinds of hair cells: inner and outer.
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Harmonics
Pure-tone components of a complex tone that have frequencies that are multiples of the fundamental frequency.
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Hertz
The unit for designating the frequency of a tone. One Hertz equals one cycle per second.
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Higher harmonics
Pure tones with frequencies that are whole-number (2, 3, 4, etc.) multiples of the fundamental frequency.
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Incus
The second of the three ossicles of the middle ear. It transmits vibrations from the malleus to the stapes.
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Inner Ear
The innermost division of the ear, containing the cochlea and the receptors for hearing.
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Inner Hair cell
Auditory receptor cell in the inner ear that is primarily responsible for auditory transduction and the perception of pitch.
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Leisure noise
Noise associated with leisure activities such as listening to music, hunting, and woodworking. Exposure to high levels of leisure noise for extended periods can cause hearing loss.
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Level
Short for sound pressure level or sound level. Indicates the decibels or sound pressure of a sound stimulus.
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Loudness
The quality of sound that ranges from soft to loud. For a tone of a particular frequency, loudness usually increases with increasing decibels.
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Malleus
The first of the ossicles of the middle ear. Receives vibrations from the tympanic membrane and transmits these vibrations to the incus.
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Middle ear
The small air-filled space between the auditory canal and the cochlea that contains the ossicles.
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Middle-ear muscles
Muscles attached to the ossicles in the middle ear. The smallest skeletal muscles in the body, they contract in response to very intense sounds and dampen the vibration of the ossicles.
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Noise-induced hearing loss
A form of sensorineural hearing loss that occurs when loud noises cause degeneration of the hair cells.
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Octave
Tones that have frequencies that are binary multiples of each other (2, 4, etc.). For example, an 800-Hz tone is one octave above a 400-Hz tone.
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Organ of Corti
The major structure of the cochlear partition, containing the basilar membrane, the tectorial membrane, and the receptors for hearing.
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Ossicles
Three small bones in the middle ear that transmit vibrations from the outer to the inner ear.
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Outer ear
The pinna and the auditory canal.
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Outer hair cell
Auditory receptor cells in the inner ear that amplify the response of inner hair cells by amplifying the vibration of the basilar membrane.
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Oval window
A small, membrane-covered hole in the cochlea that receives vibrations from the stapes.
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Periodic tone
A tone in which the waveform repeats
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Periodicity pitch
The constancy of a complex tone’s pitch when the fundamental frequency and other lower harmonics are eliminated.
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Phase locking
Firing of auditory neurons in synchrony with the phase of an auditory stimulus.
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Pinna
The part of the ear that is visible on the outside of the head.
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Pitch
The quality of sound, ranging from low to high, that is most closely associated with the frequency of a tone.
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Pitch neurons
Neurons that respond to stimuli associated with a specific pitch. These neurons fire to the pitch of a complex tone even if the first harmonic or other harmonics of the tone are not present.
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Place theory of hearing
The proposal that the frequency of a sound is indicated by the place along the organ of Corti at which nerve firing is highest. Modern place theory is based on Békésy's traveling wave theory of hearing.
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Presbycusis
A form of sensorineural hearing loss that occurs as a function of age and is usually associated with a decrease in the ability to hear high frequencies. Since this loss also appears to be related to exposure to environmental sounds, it is also called sociocusis.
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Pure tone
A tone with pressure changes that can be described by a single sine wave.
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Resonance
A mechanism that enhances the intensity of certain frequencies because of the reflection of sound waves in a closed tube. Resonance in the auditory canal enhances frequencies between about 2,000 and 5,000 Hz.
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Resonant frequency
The frequency that is most strongly enhanced by resonance. The resonance frequency of a closed tube is determined by the length of the tube.
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Sound perceptual
The perceptual experience of hearing. The statement “I hear a sound” is using sound in that sense.
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Sound physical
The physical stimulus for hearing. The statement “The sound’s level was 10 dB” is using sound in that sense.
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Sound level
The pressure of a sound stimulus, expressed in decibels.
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Sound pressure level SPL
A designation used to indicate that the reference pressure used for calculating a tone’s decibel rating is set at 20 micropascals, near the threshold in the most sensitive frequency range for hearing.
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Sound wave
Pattern of pressure changes in a medium. Most of the sounds we hear are due to pressure changes in the air, although sound can be transmitted through water and solids as well.
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Stapes
The last of the three ossicles in the middle ear. It receives vibrations from the incus and transmits these vibrations to the oval window of the inner ear.
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Tectorial membrane
A membrane that stretches the length of the cochlea and is located directly over the hair cells. Vibrations of the cochlear partition cause the tectorial membrane to bend the hair cells by rubbing against them.
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Temporal coding
The connection between the frequency of a sound stimulus and the timing of the auditory nerve fiber firing.
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Timbre
The quality that distinguishes between two tones that sound different even though they have the same loudness, pitch, and duration. Differences in timbre are illustrated by the sounds made by different musical instruments.
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Tip links
Structures at the tops of the cilia of auditory hair cells, which stretch or slacken as the cilia move, causing ion channels to open or close.
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Tone chroma
The perceptual similarity of notes separated by one or more octaves.
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Tone height
The increase in pitch that occurs as frequency is increased.
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Tonotopic map
An ordered map of frequencies created by the responding of neurons within structures in the auditory system. There is a tonotopic map of neurons along the length of the cochlea, with neurons at the apex responding best to low frequencies and neurons at the base responding best to high frequencies.
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Traveling wave
In the auditory system, vibration of the basilar membrane in which the peak of the vibration travels from the base of the membrane to its apex.
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Tympanic membrane
A membrane at the end of the auditory canal that vibrates in response to vibrations of the air and transmits these vibrations to the ossicles in the middle ear.
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Acoustic shadow
The shadow created by the head that decreases the level of high-frequency sounds on the opposite side of the head. The acoustic shadow is the basis of the localization cue of interaural level difference.
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Architectural acoustics
The study of how sounds are reflected in rooms. An important concern of architectural acoustics is how these reflected sounds change the quality of the sounds we hear.
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Auditory localization
The perception of the location of a sound source.
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Auditory receiving area A1
The area of the cortex, located in the temporal lobe, that is the primary receiving area for hearing.
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Auditory scene
The sound environment, which includes the locations and qualities of individual sound sources.
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Auditory scene analysis
The process by which sound stimuli produced by the different sources in an auditory scene become perceptually organized into sounds at different locations and into separated streams of sound.
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Auditory space
Perception of where sounds are located in space. Auditory space extends around a listener’s head in all directions, existing wherever there is a sound.
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Auditory stream segregation
The effect that occurs when a series of sounds that differ in pitch or timbre are played so that the tones become perceptually separated into simultaneously occurring independent streams of sound.
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Azimuth
In hearing, specifies locations that vary from left to right relative to the listener.
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Belt area
Auditory area in the temporal lobe that receives signals from the core area and sends signals to the parabelt area.
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Binaural cue
Sound localization cue that involves both ears. Interaural time difference and interaural level difference are the primary binaural cues.
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Cochlear nucleus
The nucleus where nerve fibers from the cochlea first synapse.
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Coincidence detectors
Neurons in the Jeffress neural coincidence model, which was proposed to explain how neural firing can provide information regarding the location of a sound source. A neural coincidence detector fires when signals from the left and right ears reach the neuron simultaneously. Different neural coincidence detectors fire to different values of interaural time difference.
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Cone of confusion
A surface in the shape of a cone that extends out from the ear. Sounds originating from different locations on this surface all have the same interaural level difference and interaural time difference, so location information provided by these cues is ambiguous.
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Core area
The area in the temporal lobe that includes the primary auditory cortex (A1) and some nearby areas. Signals from the core area are transmitted to the belt area of the auditory cortex.
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Direct sound
Sound that is transmitted directly from a sound source to the ears.
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Distance
How far a stimulus is from the observer. In hearing, the distance coordinate specifies how far the sound source is from the listener.
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Elevation
In hearing, sound locations that are up and down relative to the listener.
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Indirect sound
Sound that reaches a listener’s ears after being reflected from a surface such as a room’s walls.
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Inferior colliculus
A nucleus in the hearing system along the pathway from the cochlea to the auditory cortex. The inferior colliculus receives inputs from the superior olivary nucleus.
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Interaural level difference ILD
The difference in the sound pressure (or level) between the left and right ears. This difference creates an acoustic shadow for the far ear. The ILD provides a cue for sound localization for high-frequency sounds.
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Interaural time difference ITD
When a sound is positioned closer to one ear than to the other, the sound reaches the close ear slightly before reaching the far ear, so there is a difference in the time of arrival at the two ears. The ITD provides a cue for sound localization.
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ITD tuning curve
A plot of the neuron’s firing rate against the ITD (interaural time difference).
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Jeffress model
The neural mechanism of auditory localization that proposes that neurons are wired to each receive signals from the two ears, so that different neurons fire to different interaural time differences (ITD).
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Location cue
In hearing, characteristics of the sound reaching the listener that provide information regarding the location of a sound source.
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Medial geniculate nucleus
An auditory nucleus in the thalamus that is part of the pathway from the cochlea to the auditory cortex. The medial geniculate nucleus receives inputs from the inferior colliculus and transmits signals to the auditory cortex.
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Melodic channeling
An illusion that occurs when successive notes of a scale are presented alternately to the left and right ears. Even though each ear receives notes that jump up and down in frequency, smoothly ascending or descending scales are heard in each ear.
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Melody schema
A representation of a familiar melody that is stored in a person’s memory. Existence of a melody schema makes it more likely that the tones associated with a melody will be perceptually grouped.
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Metrical structure
The underlying beat of music
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Monaural cue
Sound localization cue that involves one ear.
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Multisensory interaction
Use of a combination of senses. For example, for vision and hearing, seeing a person’s lips move while listening to the person speak.
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Parabelt area
Auditory area in the temporal lobe that receives signals from the belt area.
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Precedence effect
The effect that occurs when two identical or very similar sounds reach a listener’s ears separated by a time interval of less than about 50 to 100 ms, and the listener hears the first sound that reaches his or her ears.
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Primary auditory cortex A1
An area of the temporal lobe that receives signals via nerve fibers from the medial geniculate nucleus in the thalamus.
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Reverberation time
The time it takes for a sound produced in an enclosed space to decrease to 1/1,000th of its original pressure.
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Rhythmic pattern
In music, the series of changes across time (a mixture of shorter and longer notes) in a temporal pattern.
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Scale illusion
An illusion that occurs when successive notes of a scale are presented alternately to the left and right ears. Even though each ear receives notes that jump up and down in frequency, smoothly ascending or descending scales are heard in each ear. Also called melodic channeling.
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Signal to noise ratio
The level of a sound signal in decibels minus the level of background noise in decibels.
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Spectral cue
In hearing, the distribution of frequencies reaching the ear that are associated with specific locations of a sound. The differences in frequencies are caused by interaction of sound with the listener’s head and pinnae.
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Subcortical structure
Structure below the cerebral cortex. For example, the superior colliculus is a subcortical structure in the visual system. The cochlear nucleus and superior olivary nucleus are among the subcortical structures in the auditory system.
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Superior olivary nucleus
A nucleus along the auditory pathway from the cochlea to the auditory cortex. The superior olivary nucleus receives inputs from the cochlear nucleus.
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Two flash illusion
An illusion that occurs when one flash of light is presented, accompanied by two rapidly presented tones. Presentation of the two tones causes the observer to perceive two flashes of light.
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Ventriloquism effect
When sound is heard coming from a seen location, even though it is actually originating somewhere else. Also called visual capture.
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Vestibular system
The mechanism in the inner ear that is responsible for balance and sensing the position of the body.
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Visual capture
When sound is heard coming from a seen location, even though it is actually originating somewhere else. Also called the ventriloquism effect.
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Acoustic signal
The pattern of frequencies and intensities of the sound stimulus.
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Acoustic stimulus
The pattern of frequencies and intensities of the sound stimulus.
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Aphasia
Difficulties in speaking or understanding speech due to brain damage.
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Articulator
Structure involved in speech production, such as the tongue, lips, teeth, jaw, and soft palate.
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Audiovisual speech perception
A perception of speech that is affected by both auditory and visual stimulation, as when a person sees a tape of someone saying /ga/ with the sound /ba/ substituted and perceives /da/. Also called the McGurk effect.
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Broca's aphasia
Language problems, caused by damage to Broca’s area in the frontal lobe, characterized by labored and stilted speech and short sentences.
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Broca's area
An area in the frontal lobe that is important for language perception and production. One effect of damage is difficulty in speaking.
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Categorical perception
In speech perception, perceiving one sound at short voice onset times and another sound at longer voice onset times. The listener perceives only two categories across the whole range of voice onset times.
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Coarticulation
The overlapping articulation that occurs when different phonemes follow one another in speech. Because of these effects, the same phoneme can be articulated differently depending on the context in which it appears. For example, articulation of the /b/ in boot is different from articulation of the /b/ in boat.
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Dual-stream model of speech perception
Model that proposes a ventral stream starting in the temporal lobe that is responsible for recognizing speech, and a dorsal stream starting in the parietal lobe that is responsible for linking the acoustic signal to the movements used to produce speech.
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Formant
Horizontal band of energy in the speech spectrogram associated with vowels.
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Formant transition
In the speech stimulus, the rapid shift in frequency that precedes a formant.
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Indexical characteristic
Characteristic of the speech stimulus that indicates information about a speaker, such as the speaker’s age, gender, or emotional state.
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McGurk effect
A perception of speech that is affected by both auditory and visual stimulation, as when a person sees a tape of someone saying /ga/ with the sound /ba/ substituted and perceives /da/. Also called audiovisual speech perception.
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Motor theory of speech perception
A theory that proposes a close link between how speech is perceived and how it is produced. The idea behind this theory is that when we hear a particular speech sound, this activates the motor mechanisms that are responsible for producing that sound, and it is the activation of these motor mechanisms that enable us to perceive the sound.
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Multimodal
The involvement of a number of different senses in determining perception. For example, speech perception can be influenced by information from a number of different senses, including audition, vision, and touch.
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Phoneme
The shortest segment of speech that, if changed, changes the meaning of a word.
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Phonemic restoration effect
An effect that occurs in speech perception when listeners perceive a phoneme in a word even though the acoustic signal of that phoneme is obscured by another sound, such as white noise or a cough.
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Phonetic boundary
The voice onset time when perception changes from one speech category to another in a categorical perception experiment.
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Shadowing
Listeners’ repetition aloud of what they hear as they are hearing it.
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Sound spectrogram
A plot showing the pattern of intensities and frequencies of a speech stimulus.
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Speech segmentation
The process of perceiving individual words from the continuous flow of the speech signal.
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Statistical learning
The process of learning about transitional probabilities and other characteristics of the environment. Statistical learning for properties of language has been demonstrated in young infants.
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Transitional probabilities
In language, the chances that one sound will follow another sound. Every language has transitional probabilities for different sounds. Part of learning a language involves learning about the transitional probabilities in that language.
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Voice cells
Neurons in the temporal lobe that respond more strongly to same-species voices than to calls of other animals or to “non-voice” sounds.
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Voice onset time (VOT)
In speech production, the time delay between the beginning of a sound and the beginning of the vibration of the vocal chords.
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Wernicke's aphasia
An inability to comprehend words or arrange sounds into coherent speech, caused by damage to Wernicke’s area.
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Wernicke's area
An area in the temporal lobe involved in speech perception. Damage to this area causes Wernicke’s aphasia, which is characterized by difficulty in understanding speech.
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Word deafness
Occurs in the most extreme form of Wernicke’s aphasia, when a person cannot recognize words, even though the ability to hear pure tones remains intact.
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Active touch
Touch in which the observer plays an active role in touching and exploring an object, usually with his or her hands.
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Affective (emotional) component of pain
The emotional experience associated with pain—for example, pain described as torturing, annoying, frightful, or sickening.
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Cutaneous senses
The ability to perceive sensations, such as touch and pain, that are based on the stimulation of receptors in the skin.
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Direct pathway model of pain
The idea that pain occurs when nociceptor receptors in the skin are stimulated and send their signals to the brain. This model does not account for the fact that pain can be affected by factors in addition to stimulation of the skin.
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Duplex theory of texture perception
The idea that texture perception is determined by both spatial and temporal cues that are detected by two types of receptors. Originally proposed by David Katz and named the “duplex theory” by Hollins.
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Endorphin
Chemical that is naturally produced in the brain and that causes analgesia.
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Epidermis
The outer layers of the skin, including a layer of dead skin cells.
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Exploratory procedures EPs
People’s movements of their hands and fingers while they are identifying three-dimensional objects by touch.
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Gate control model
Melzack and Wall’s idea that perception of pain is controlled by a neural circuit that takes into account the relative amount of activity in nociceptors, mechanoreceptors, and central signals. This model has been used to explain how pain can be influenced by factors in addition to stimulation of receptors in the skin.
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Grating Acuity
In the cutaneous senses, a measure of acuity on the skin that is the narrowest spacing of a grooved surface on the skin for which orientation can be accurately judged. Can also be applied to detecting the orientation of a visual grating stimulus
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Haptic perception
The perception of three-dimensional objects by touch.
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Homunculus
Latin for “little man”; refers to the topographic map of the body in the somatosensory cortex.
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Inflammatory pain
Pain caused by damage to tissues, inflammation of joints, or tumor cells. This damage releases chemicals that create an “inflammatory soup” that activates nociceptors.
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Kinesthesis
The sense that enables us to feel the motions and positions of the limbs and body.
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Mechanoreceptor
Receptor that responds to mechanical stimulation of the skin, such as pressure, stretching, or vibration.
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Medial lemniscal pathway
A pathway in the spinal cord that transmits signals from the skin toward the thalamus.
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Meissner corpuscle RA1
A receptor in the skin, associated with RA1 mechanoreceptors. It has been proposed that the Meissner corpuscle is important for perceiving tactile slip and for controlling the force needed to grip objects.
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Merkel receptor
A disk-shaped receptor in the skin associated with slowly adapting fibers and the perception of fine details.
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Multimodal nature of pain
The fact that the experience of pain has both sensory and emotional components.
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Naloxone
A substance that inhibits the activity of opiates. It is hypothesized that naloxone also inhibits the activity of endorphins and therefore can have an effect on pain perception.
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Neuropathic pain
Pain caused by lesions or other damage to the nervous system.
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Nociceptive pain
This type of pain, which serves as a warning of impending damage to the skin, is caused by activation of receptors in the skin called nociceptors.
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Nociceptor
A fiber that responds to stimuli that are damaging to the skin.
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Opioid
A chemical such as opium, heroin, and other molecules with related structures that reduce pain and induce feelings of euphoria.
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Pacinian corpuscle RA2 or PC
A receptor with a distinctive elliptical shape associated with RA2 mechanoreceptors. It transmits pressure to the nerve fiber inside it only at the beginning or end of a pressure stimulus, and is responsible for our perception of vibration and fine textures that are perceived when moving the fingers over a surface.
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Pain matrix
The network of structures in the brain that are responsible for pain perception.
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Passive touch
A situation in which a person passively receives tactile stimulation.
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Proprioception
The sensing of the position of the limbs.
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Rapidly adapting RA receptor
Mechanoreceptors that respond with bursts of firing just at the onset and offset of a pressure stimulus. The Meissner corpuscle and the Pacinian corpuscle are rapidly adapting receptors.
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Ruffini cylinder
A receptor structure in the skin associated with slowly adapting fibers. It has been proposed that the Ruffini cylinder is involved in perceiving “stretching.”
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Secondary somatosensory cortex S2
The area in the parietal lobe next to the primary somatosensory area (S1) that processes neural signals related to touch, temperature, and pain.
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Sensory component of pain
Pain perception described with terms such as throbbing, prickly, hot, or dull.
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Slowly adapting SA receptor
Mechanoreceptors located in the epidermis and the dermis that respond with prolonged firing to continued pressure. The Merkel receptor and the Ruffini cylinder are slowly adapting mechanoreceptors.
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Somatosensory receiving area S1
An area in the parietal lobe that receives inputs from the skin and the viscera associated with somatic senses such as touch, temperature, and pain.
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Somatosensory system
The system that includes the cutaneous senses (senses involving the skin), proprioception (the sense of position of the limbs), and kinesthesis (sense of movement of the limbs).
393
Spatial cue
In tactile perception, information about the texture of a surface that is determined by the size, shape, and distribution of surface elements such as bumps and grooves.
394
Spinothalamic pathway
One of the nerve pathways in the spinal cord that conducts nerve impulses from the skin to the somatosensory area of the thalamus.
395
Surface texture
The visual and tactile quality of a physical surface created by peaks and valleys.
396
Synesthesia
A condition in which stimulation of one modality (such as vision) results in an experience in another modality (such as touch). For example a person with synesthesia who observes another person being touched may experience touch on the same part of his or her own body.
397
Tactile acuity
The smallest details that can be detected on the skin.
398
Temporal cue
cue In tactile perception, information about the texture of a surface that is determined by the rate of vibrations that occur as we move our fingers across the surface.
399
Transmission cell (Tcell)
According to gate control theory, the cell that receives + and – inputs from cells in the dorsal horn. T-cell activity determines the perception of pain.
400
Two-point threshold
The smallest separation between two points on the skin that is perceived as two points; a measure of acuity on the skin.
401
Ventrolateral nucleus
Nucleus in the thalamus that receives signals from the cutaneous system.
402
2-deoxyglucose technique
A procedure that involves injecting a radioactive 2-deoxyglucose (2DG) molecule into an animal and exposing the animal to oriented stimuli. The 2DG is taken up by neurons that respond to the orientation. This procedure is used to visualize orientation columns in the cortex.
403
Across fiber patterns
The pattern of nerve firing that a stimulus causes across a number of neurons. Also referred to as distributed coding.
404
Amiloride
A substance that blocks the flow of sodium into taste receptors.
405
Amygdala
A subcortical structure that is involved in emotional responding and in processing olfactory signals.
406
Anosmia
Loss of the ability to smell due to injury or infection.
407
Bimodal neuron
A neuron that responds to stimuli associated with more than one sense.
408
Calcium imaging
A method of measuring receptor activity by using fluorescence to measure the concentration of calcium inside the receptor. This technique has been used to measure the activation of olfactory receptor neurons.
409
Chemotopic map
The pattern of activation in the olfactory system in which chemicals with different properties create a “map” of activation based on these properties. For example, there is evidence that chemicals are mapped in the olfactory bulb based on carbon-chain length.
410
Detection threshold
The minimum amount of energy that can be detected. The detection threshold for smell is the lowest concentration at which an odorant can be detected. This threshold is distinguished from the recognition threshold, which requires a higher concentration of odorant.
411
Flavour
The perception that occurs from the combination of taste and olfaction.
Frontal operculum cortex An area in the frontal lobe of the cortex that receives signals from the taste system.
412
Glomeruli
Small structures in the olfactory bulb that receive signals from similar olfactory receptor neurons. One function of each glomerulus is to collect information about a small group of odorants.
413
Insula
An area in the frontal lobe of the cortex that receives signals from the taste system and is also involved in the affective component of the perception of pain.
414
Macrosmatic
Having a keen sense of smell; usually important to an animal’s survival.
415
Microsmatic
Having a weak sense of smell. This usually occurs in animals like humans, in which the sense of smell is not crucial for survival.
416
Nasal pharynx
A passageway that connects the mouth cavity and the nasal cavity.
417
Neurogenesis
The cycle of birth, development, and death of a neuron. This process occurs for the receptors for olfaction and taste.
418
Nontaster
A person who cannot taste the compound phenylthiocarbamide (PTC).
419
Nucleus of the solitary tract
The nucleus in the brain stem that receives signals from the tongue, the mouth, and the larynx transmitted by the chorda tympani, glossopharyngeal, and vagus nerves.
420
Odor map
The pattern of activation in the olfactory system in which chemicals with different properties create a “map” of activation based on these properties. For example, there is evidence that chemicals are mapped in the olfactory bulb based on carbon-chain length. Also called chemotopic map or odotoptic map.
421
Odor object
The source of an odor, such as coffee, bacon, a rose, or car exhaust.
422
Odotoptic map
The pattern of activation in the olfactory system in which chemicals with different properties create a “map” of activation based on these properties. For example, there is evidence that chemicals are mapped in the olfactory bulb based on carbon-chain length. Also called chemotopic map or odor map.
423
Olfaction
The sense of smell. Usually results from stimulation of receptors in the olfactory mucosa.
424
olfactometer
A device that presents olfactory stimuli with great precision.
425
Olfactory bulb
The structure that receives signals directly from the olfactory receptors. The olfactory bulb contains glomeruli, which receive these signals from the receptors.
426
Olfactory mucosa
The region inside the nose that contains the receptors for the sense of smell.
427
Olfactory receptor
A protein string that responds to odor stimuli.
428
Olfactory receptor neurons ORNs
Sensory neurons located in the olfactory mucosa that contain the olfactory receptors.
429
Optical imaging
A technique that has been used to measure the activity of large areas of the olfactory bulb by measuring the intensity of red light reflected from the bulb.
430
Oral capture
The condition in which sensations from both olfaction and taste are perceived as being located in the mouth.
431
Orbitofrontal cortex
An area in the frontal lobe, near the eyes, that receives signals originating in the olfactory receptors. Also known as the secondary olfactory cortex.
432
Papillae
Ridges and valleys on the tongue, some of which contain taste buds. There are four types of papillae: filiform, fungiform, foliate, and circumvallate.
433
Pheromone
Chemical signal released by an individual that affects the physiology and behavior of other individuals.
434
Piriform cortex
An area under the temporal lobe that receives signals from glomeruli in the olfactory bulb. Also called the primary olfactory cortex.
435
Primary olfactory area
A small area under the temporal lobe that receives signals from glomeruli in the olfactory bulb. Also called the piriform cortex.
436
Proust effect
The elicitation of memories through taste and olfaction. Named for Marcel Proust, who described how the taste and smell of a tea-soaked madeleine cake unlocked childhood memories.
437
Recognition profile
The pattern of olfactory activation for an odorant, indicating which ORNs (olfactory receptor neurons) are activated by the odorant.
438
Retronasal route
The opening from the oral cavity, through the nasal pharnyx, into the nasal cavity. This route is the basis for the way smell combines with taste to create flavor.
439
Secondary olfcatory area
An area in the frontal lobe, near the eyes, that receives signals originating in the olfactory receptors. Also known as the orbitofrontal cortex.
440
Sensory specific satiety
The effect on perception of the odor associated with food eaten to satiety (the state of being satiated or “full”). For example, after eating bananas until satiety, the pleasantness rating for vanilla decreased slightly (but was still positive), but the rating for banana odor decreased much more and became negative.
441
Supertaster
A person who is especially sensitive to 6-n- propylthiouracil (PROP), a bitter substance.
442
Taste bud
A structure located within papillae on the tongue that contains the taste cells.
443
Taste cell
Cell located in taste buds that causes the transduction of chemical to electrical energy when chemicals contact receptor sites or channels located at the tip of this cell.
444
Taste pore
An opening in the taste bud through which the tips of taste cells protrude. When chemicals enter a taste pore, they stimulate the taste cells and result in transduction.
445
Taster
A person who can taste the compound phenylthiocarbamide (PTC).
446
Video microscopy
A technique that has been used to take pictures of papillae and taste buds on the tongue.
