Unit 2: Sensation And Perception Flashcards
Acquisition of Sensory information from the environment
Involves the absorption of energy (e.g. light, sound waves) by sensory organs (e.g. eyes, ears) and the conversion of that energy into the electrical signals used by the nervous system
Sensation
Interpreting and understanding sensory information
Translating sensory input into something meaningful
Perception
The conversion of physical signals into neural responses (i.e. electrical signals) by specialized receptors that respond to energy from the environment.
Transduction
Is perception a perfect reflection of the physical world?
No, perception is an interpretation of the information coming in from the physical world.
distance over which an electromagnetic wave repeats
wavelength
study of the quantitative relationship between physical stimuli and the sensations they produce.
psychophysics
A mathematical formula describing the relationship between stimulus intensity and perceptual intensity.
“as stimulus intensity increases, larger changes are required for the changes to be percieved”.
Fechner’s Law
Why is Gustav Fechner considered to be the true founder of experimental psychology?
He proposed the mind could be studied by examining the relationship between physical stimulation and a person’s experience.
(ie. argued mind could be studied scientifically)
Fechner proposed serveral methods to measure _______, or the smallest stimulus intensity that an be detected.
i.e., when measuring tone, user responds with yes/no of stimulus using a pattern of ascending/descending order. The threshold is the average of crossovers from the “yes” and “no” response.
absolute threshold
What sense does this absolute threshold describe?
Stars at night or a candle flame 30 miles away on a dark, clear night.
Vision
What sense does this absolute threshold describe?
A ticking watch 20 feet away, with no other noises
Hearing
What sense does this absolute threshold describe?
A tilt of less than half a minute on a clock face.
Vestibular
What sense does this absolute threshold describe?
a teaspoon of sugar in 2 gallons of water.
taste
What sense does this absolute threshold describe?
a drop of perfume in 3 rooms
smell
What sense does this absolute threshold describe?
the wing of a fly falling on your cheek from a height of 3 inches
touch
What method would you use if you want to examine the ability to name or identify familiar objects in the environment?
Identification/naming tasks
often measure reaction time for naming, instead of accuracy
What method would be used examine the ability to search for and detect a certain stimulus in the environment?
Visual search tasks
Light is part of the ____ _____, the continuum of all wavelengths of radiated energy. Includes X-rays at the short end to radio and tv signals at the long end.
electromagnetic spectrum
what is the “visible spectrum”?
a small range of wavelengths. Visible because we have receptors that are sensitive to those wavelengths.
the distance between the peaks of a wave. interpreted as hue (or color). different wavelengths are interpreted as different hues.
Wavelength
size of the peaks and troughs in the waves. interpreted as brightness.
Amplitude.
What are the key structures of the eye?
cornea
iris
pupil
lens
retina
rods and cones
optic disc
blind spot
which key structure of the eye?
light first passes through the transparent ______, where there’s some initial focusing of light. Due to the rigid structure, focus cannot be adjusted through this structure.
Cornea
which key structure of the eye?
muscular tissue that gives eyes their color. reflexively expands and contracts based on light level, letting more and less light through pupil
iris
which key structure of the eye?
an opening in the center of the iris, which appears black in color.
pupil
which key structure of the eye?
transparent, flexible structure just behind the pupil. Muscles attached can change the shape and alter curvature.
lens
changing the curvature of the lens allows for ______, an adjustment of the focus for objects at differetn distances.
accommodations
close objects seen clearly, distant objects appear blurry.
corena and/or lense bend light too much or the eye is too long
Nearsightedness (myopia)
distant objects seen clearly, close objects appear blurry.
usually, eye is too short.
Farsightedness (hyperopia)
which key structure of the eye?
the cornea and lens focus light onto the back of the eye, an area called______.
retina
What do we call the visual receptors within the retina?
rods and cones
which key structure of the eye?
hole in the retina where axons leave, and blood vessels enter/leave.
Optic disc
which key structure of the eye?
Lack of visual receptors so the brain “fills in” the missing part of the image, so we don’t typically notice.
blind spot
visual receptors located in the innermost layer of the retina.
photoreceptors
What are the 2 types of photoreceptors?
rods and cones
Which photoreceptor are adapted for vision in dim light and 100x more sensitive (in dim light) because resources are pooled.
humans have approximately 100 million
rods
which photoreceptor is adapted for perceiving color, detail in bright light, and plays largest role in color perception; therefore, hard to see color well in low-light conditions.
concentrated most heavily in the center of the retina.
humans have approx 6 million.
cones.
center of the retina where cones are most heavily concentrated in and visual acuity is greatest.
fovea.
the photoreceptors (rods and cones) have _____, molecules that experience a chemical change when they absorb light.
photopigments
the axons of the _____ _____ join to form the optic nerve and elave the eye throught the optic disc.
Ganglion Cells
What does the massive convergence that occurs within the retina (100+ million rods and cones down to 1 million axons leaving the eye) tell us?
there is already extensive integration and compression of signals.
Photoreceptors (rods and cones) converge onto ganglion cells in the retina to create what?
For vision, the ____ ____ is the pattern of light that produces a neuroal response in that cell.
receptive fields (of cells in the retina).
The most common receptive field in the retina is is curcular with a ____-_____ _____; cells respond more when light falls in the circular center, less when light falls in the circular surround.
center-surround arrangement.
Ganglion cells are most receptive to:
spots of light of a particular size (contrast)
the optice nerves from each eye go to the ___ ____, where half of the axons cross over
optic chiasm
The change in the curvature of the lens, in order to adjust the focus for objects at different distances, is called what?
Accommodations
Which type of photoreceptor provides the best acuity (sharpness and precise detail)?
Cones
What does Hubel and Weisel’s reserach on firing rate of individual neurons in the primary visual cortex of cats tell us about the recpetive fields of those neurons?
Unlike the circular-receptive fields in the eye, the receptive fields in the primary visual cortex are linear
Tsao and colleagues examined the response of individual neurons in visual processing areas of the cortex of monkeys, focusing on neurons beyond the primary visual cortex, that were further along the so-called “what” pathway. They examined neuronal responses to a variety of stimuli, including hands, bodies, faces, fruits, gadgets, etc. What did they find?
Neurons selectively responded to faces.
The _____ is a rigid structure that does a fixed amount of focusing of light. The ______ is a flexible structure that can adjust the focus.
cornea, lens
Ganglion cells in the eye respond most vigorously to spots of light of a certain size. Cells in the primary visual cortex, on the other hand, respond most vigorously to lines or bars of a specific orientation. In other words, these cells have different what?
receptive fields
Beiderman (1987) proposed that we detect 3D features called ____. What do they do?
Geons
assemble into complex 3D objects for perceiving.
What type of processing involves detecting features and assembling them into more complex forms?
Examples:
-simple features built-up into letters, letters build into words
-geons are built into 3D objects
bottom-up processing
What type of processing involves context, as well as knowledge, beliefs, and expectations, to organize and interpret what we see?
top-down processing
individual neurons in the primary visual cortex responded most vigorously to lines or edges at a specific orientation is commonly interpreted as evidence that indivudal neurons are functioning as feature detectors. This is evidence for ____.
Feature Analysis
Althought the majority of the shape’s lines are actually missing, it’s typically perceived as a solid white triangle sitting in front of three black circles. The lack of features detected describes the phenomena showing ____ is insufficient.
Feature Analysis
what is described by “readiness or bias to perceive a stimulus in a particular way”. This differs between viewers of different ages. exact same features are perceived differently but are influenced by expectations and interpretations, based on an individual’s _____.
perceptual set
What is a tendency to experience a stable perception in the face of changing sensory inputs. such as tend to view objects as having a stable size, shape, color, etc.
Perceptual constancies
Is feature-analysis sufficient for explaining object perception?
No, we perceive whole objects even when features are missing. Images can be interpreted differently, based on changes in perceptual set or context, even when the features stay the same. Images can be percieved as the same object when the features change.
What approach proposed various principles of perceptual organization to explain how elements tend to be grouped together to form objects/wholes.
In other words, “the whole is different than the sum of the parts”. (ie. a melody broken into individual notes is no longer a melody).
Gestalt approach
The key Gestalt principles of organization are:
Proximity
similarity
closure
simplicity
continuation
common fate
Which key gestalt principle of organization does the below describe?
when objects, colors, sized, or forms appear similar enough to be perceived as a group or pattern
Similarity
Which key gestalt principle of organization does the below describe?
the idea that objects that are close together are perceived as a group/unit.
Proximity
Which key gestalt principle of organization does the below describe?
the idea that the brain will fill in missing parts of an image or design to create a whole picture.
closure
Which key gestalt principle of organization does the below describe?
the idea that people will perfceive and interpret ambiguous or complex images in the simplest form possible.
simplicity
Which key gestalt principle of organization does the below describe?
the idea that things are arranges in a continual line or curve are related to one another
continuation
Which key gestalt principle of organization does the below describe?
the idea that people group together things that appear to be moving in the same direction
common fate
What is experienced when things are perceived inaccurately, in a way that doesn’t reflect the world?
Visual illusions
Some evidence showing the specialized perception of faces include include:
- Better recognition for ____ than other types of stimuli, like animals, obejcts, shapes, etc.
- our eyes automatically shift their gaze to face stimuli significantly ____ (faster or slower) than other types of stimuli.
- very young infants prefer to look at faces over other stimuli.
faces; faster
occurs when search times are equally fast across set sizes (ie. equally fast for 16, 36, 64 photos)
pop-out effect
is the pop-out effect observed for Upright faces?
yes. Face stimuli are processed more efficiently, specifically human faces.
is the pop-out effect observed for object like cars?
no
is the pop-out effect observed for animal/inverted/scrambled faces?
no
refers to the fact that, unlike objects, faces are processed in terms of wholes rather than as a collection of parts or features.
holistic processing
____ information refers to the spatial relations among facial components
configural information
_____ information pertains to the shape or size of each facial component
featural information
a phenomenon where it becomes more difficult to detect local feature changes in an upside-down face, despite identical changes being obvious in an upright face.
Thatcher effect
phenomenon where identifying inverted faces compared to upright faces is much more difficult than doing the same for non-facial objects.
Compromising configural information (by inverting) DOES affect perception of face stimuli. Compromising configural information (by inverting) does NOT affect perception with car stimuli.
face inversion effect.
Some theorists beleive the FFA is best characterized as a ______, active with faces because we are all face experts.
Visual expertise Module
condition where individuals have difficulty recognizing the faces of familiar people (even close friends or family members, even their own reflection in the mirror), although they can identify these same people as soon as they hear them speak.
Condition occurs when there is damage to the temporal lobe in the area of the FFA and provides evidence that the FFA is important for face perception
Prosopagnosia.
the outcome of the greebles study (1999), where an fMRI examined the FFA response to faces/objects called “greebles”, the fusiform face area in the participants’ brains responded ______ to greebles as it did to human faces.
Just as well or not as well?
Just as well
What is the directing or orienting of our visual ssytem toward a subset of information or events in our visual world?
Visual attention
In an _____ mode of attention, jthe observer has a goal in mind and guides the attentional process in service of that goal?
active
What is the more modern concept of “active mode of attention”, where attention is guided by goals, knwoledge, and expectations?
Goal-driven attention
In a ____ mode of attention, attention is “grabbed” by some aspect of the environment, without any goal in mind
Passive
what is the more modern concept of “passive mode of attention”, where attention (involuntarily or unintentionally) is being driven by the characteristics of the stimulus?
stimulus-driven attention
Just as a spotlight can be moved around, attention can be directed and redirected to various things in the environment. Just as a spotlight best illuminates what is at its center, things that are within the central focus of attention receive more thorough processing.
Just as you can still see things outside of the spotlight to some extent, things outside of the focus of attention still receive some processing.
Spotlight metaphor
What causes shifts in attention?
Visual Salience
goals
knowledge and expectations
task demands
aspects of the visual world that are markedly different from their surroundings are said to have ______.
Things that stand out.
visual salience.
salience in color, contrast, movement, orientation, ect can attract attention.
Salience can attract our attention involuntarily or unintentionally. This “grabbing” of our attention that can detract from our goals is know as what?
attentional capture
term defined by “pauses to focus and bring in information”
fixations
term defined by “jerky movements to move to new locations”
saccadic eye movements
How do we aim our fovea at one thing after another, and bring to bear the more detailed visual processing of the fovea?
Fixations and saccadic eye movements.
.What search can detect the target by just focusing on one feature (e.g. the color red) and can be detected extremely fast despite set size, meaning it has a pop-out effect.
feature searches
What search must carefully consider the combination of features (e.g. shape AND color)? as set size increases, it takes longer to search for the target.
No pop-out effect
conjuction searches
Term described by “no effect of set size” and reveals that there’s a highly efficient search in which you don’t need to carefully focus attention from item to item.
Pop-out effect
when _____ are combined, each absorb the wavelengths they absorb when alone. The resulting color that you perceive is determined by the remaining reflected wavelengths that don’t get absorbed during subtractive color mixing
paint
what do we call the process of wavelengths being subtracted out of the light signal?
subtractive color mixing
what do we call the process of wavelengths being added to the light signal?
additive color mixing
the colors we see in objects/surfaces are primarily determined by what?
the particular mix of wavelengths that get reflected into our eyes.
How is color perception just the mind’s interpretation?
We perceive color because of the way our nervous system responds to certain types of energy. The nervous system constructs color from wavelengths through the action of the cones (and rest of visual system?)
Color is not a property of light, nor is it a property of objects.
What theory is described by “three color mechanisms make up the human experience of color” (Young 1802, Helmholtz 1852)?
Trichromatic theory
The Trichromatic Theory is based on the observation that all colors that we are able to distinguish can be produced by this right mix of three primary colors (two colors is not enough, four is more than needed?
What did researchers reason with this?
That we must have three receptor mechanisms, or cones, that absorbe different wavelengths of light
What theory proposes that color experience is based on the opponent pairs of colors (red-green; yellow-blue)
-described using a mechanism by which increased responding to red is accompanied by decreased responding to green (&vice versa); same for the yellow-blue pairing
Opponent-process theory
What are some observations that motivate opponent-process theory?
There are ganglion cells in the retina with a center-surround arrangement, such that they are maximally stimulated by spots of light; we have similar ganglion cells when it comes to cones called: Color-Opponent Ganglion Cells
Trichromatic theory and opponent-process theory were historically considered competing theories, but why do we know they are both correct?
There are theree color mechanisms at the level of the receptors.
But these receptors converge onto the ganglion cells in a manner that creates the red-green and yellow-blue opponent processes.
What shows that color perception isn’t only about the wavelength of light reflecting from an object?
Example being center square going down each column is exactly the same, but is perceived as different color in different surrounding contexts.
Color contrast effect
what do we call perceiving an object as having the same color despite changes in the illumination conditions?
shows that our mind takes into account the context, the surroundings, the viewing conditions.
Color constancies
What condition refers to having two functioning cones, resulting in a “flatter” color experience?
Dichromacy
What condition refers to having no functioning cones, so vision is created by rods alone; and results in True color blindness (only see in shades of lightness/grey)
Achromatopsia
What conditions refers to having three functioning cones and is most common among humans?
Trichromacy
Hansel et al (2006) examinde viewers’ color perceptions of gray objects on gray backgrounds, for fruits/veggies vs. circles of light. Why were bananas perceived as slightly yellow, carrots as slightly orange, cucumbers as slightly green, etc?
color perception is not only about the wavelength of light reflecting from an object. It’s also dependent on one’s knowledge and experiences.
Patterns of compressed/decompressed air and is the stimulus for hearing
sound waves
What are the key characteristics of sounds waves?
frequency
amplitude
Number of cycles or waves per second, measured in units called hertz (Hz)
Frequency
Size or intensity of the pressure change, measure in units called decibels (db)
Amplitude
Frequency of sound is what we interpret as the _____ of a sound. The greater the frequency, the higher the ____ (but don’t perfectly correspond).
pitch
The amplitude of sounds is what we interpret as _____. The greater the amplitude = more ____.
loudness
Our range of sensitivity to amplitude is so huge that we can detect a sound ten million times louder than the softerst one we can detect. Scientists therefore converted the large range of pressures we can detect to a more manageable scale called what?
Decibel scale
Which section of the human ear?
sound is conducted as sound waves through air
Outer ear
Which section of the human ear?
sound is conducted as vibration through moveable bones
middle ear
Which section of the human ear?
sound is conducted as vibration in fluids and membranes
inner ear
Which key structure of the outer ear?
the external flap of the ear, which funnels sound into the auditory canal; sound coming from the front’side is favored
Pinna
Which key structure of the outer ear?
protects the structures of the middle and inner ear from harsh environmental conditions
Auditory Canal
Which key structure of the middle ear?
thin membrane stretched across the end of the auditory canal; responds to sounds waves by vibrating
Tympanic membrane (eardrum)
Which key structure of the middle ear?
Three bones that transmit amd amplify the vibrations of the eardrum; they form a leber system that amplifies vibrations approx 30 fold.
Ossicles
Which key structure of the inner ear?
Snail-shaped, coiled, fluid-filled structure that contains the recpetors for hearing (the hair cells)
Cochlea
Which key structure of the middle ear?
thin membrane where the last ossicle rests on the cochlea; the vibrations of the ossicles cause the this to vibrate; movement, then causes waves or oscillations of the fluids within the cochlea.
Oval window
auditory receptors are ____ cells
hair cells
What is the membrane that runs the length of the cochlea and contains the auditory recpetors called?
basilar membrane
____ in the fluid within the canals of the cochlea produce a traveling wave down the basilar membrane causing the hair cells to ____.
waves; bend.
How are sound waves transduced into neural impulses?
Mechanical energy > electrical energy
When hair cells are bent in one direction, ion channels open. The movement of ions create an electrical signal causing the release of neurotransmitters into the synapses with auditory neurons.
How are different frequencies of sound translated into different pitches?
Two theories combined:
1. Place theory
2. Frequency theory
What theory of pitch perception?
(Helmholtz, 1863) high frequencies cause the largest displacements closer to the oval window; low frequencies cause the largest displacements further down the membrane.
Different places on the cochlea are therefore “tuned” to different frequencies, enabling the brain to detect the frequency of a tone according to which hair cells along the basilar membrane are most active.
Place theory
What theory of pitch perception?
(Rutherford, 1886) The higher the sound frequency, the higher the vibration of the basilar membrane. higher freqencies would therefore cause a greater overall rate of activation of the hair cells and corresponding auditory neurons. The brain can determine the frequency of a sound by the overall rate at which the auditory neurons fire.
Frequency Theory
What is the combined theory of pitch perception?
It is the current view that place and frequency theories of pitch perception are both correct.
Frequency mechanism explains pitch perception from a very low freq, but a place mechanism for all of the remaining frequencies for 200Hz to 20,000Hz.
What is the auditory pathway to the cortex?
Neurons from the cochleas make up the auditory nerves. Fibers first synapse in the brainstem then midbrain, before continuing on to the primary auditory cortex in the temporal lobes.
How is the auditory cortex organized?
Auditory neurons are tuned to specific frequencies and maintained all the way to the cortex, so the primary auditory cortex is organized by frequency of simple sounds.
