Sensation and Perception Flashcards
Absolute Threshold
The minimum amount of a stimulus energy required to activate a sensory system (the amount of a stimulus that an individual can perceive)
Difference Thresholds
How different two stimuli must be before they’re perceived as different
Just Noticeable Difference
Ernest Weber
The amount of change necessary to predict the difference between two stimuli: THIS IS A UNIT OF MEASURE (JND)
Weber’s Law
Ernest Weber
What’s important in producing a just noticeable difference is not the absolute difference between stimuli, it is the ratio
Georg von Békésy
Empirical studies led to traveling wave theory of pitch perception which, at least partially, supported Helmholtz’s place-resonance theory
George Berkeley
Developed a list of depth cues that help us perceive depth
Donald Broadbent
Proposed filter theory of attention (attending to something allows it to be processed further), and that selective attention was all or nothing (disconfirming = Cocktail Party Phenomenon which suggests dichotic listening)
Gustav Fechner
Developed Fechner’s Law, which expresses the relationship between the intensity of the stimulus and the intensity of the sensation
Elanor Gibson and Richard Walk
Developed the visual cliff apparatus, which is used to study the development of depth perception
Hermann von Helmholtz
Developed the Young-Helmholtz trichromatic theory of color vision
Developed place-resonance theory of pitch perception
Ewald Hering
Developed opponent process theory of color vision
James Gibson
Studied depth cues (especially texture gradients) that help us to perceive depth
David Hubel and Torsten Wiesel
Studied feature detection in the visual cortex (using single-cell recording) and discovered simple, complex, and hypercomplex cells
Wolfgang Köhler
Developed theory of isomorphism
Ronald Melzack and Patrick Wall
Proposed gate theory of pain
Stanley Smith Stevens
Developed Steven’s law as an alternative to Fechner’s law
John A. Swets
Refined ROC curves in signal detection theory
Ernest Wever & Charles Bray
Proposed volley theory of pitch perception in response to a criticism of the frequency theory of pitch perception
Robert Yerkes and John Dodson
Developed Yerkes-Dodson Law which states that performance is best at intermediate levels of arousal
Fechner’s Law
Expresses the relation between the intensity of a sensation and the intensity of a stimulus
Steven’s Power Law
Relates intensity of a stimulus to the intensity of the sensation
Signal Detection Theory
The idea that other, nonsensory factors influence what a participant says she senses (i.e. experiences, motives, expectations)
Response Bias (signal detection theory)
Measures how risky the subject is in sensory decision making; based on non-sensory factors (measured by hits, misses, false alarms, correct negatives)
Sensitivity
Feature of signal detection theory that measures how well the subject can sense the stimulus
ROC Curve
Receiver Operating Characteristic Curve
Used to graphically summarize a subject’s responses in a signal detection experiment
Proportion of times a signal is reported when presented and when not presented
Stages of Sensory Information Processing
- Reception
- Transduction
- Electrochemical energy is sent to various projection areas in the brain along various neural pathways and can be processed by the nervous system
Transduction
Translation of physical energy into neural impulses or action potentials
Projection Areas
Brain areas that further analyze sensory input
Cornea
Clear dome-like wondow in front of the eye that gathers and focuses incoming light
Pupil
Hole in the iris that contracts and expands to let less or more light in
Iris
Colored part of the eye. Has involuntary muscles and autonomic nerve fibers. Controls the size of the pupil
Lens
Right behind the iris, helps control the curvature of light entering and focuses near or distant objects on the retina
Retina
In the back of the eye, like a screen - is the image detecting part of the eye. Contains rods and cones
Blind Spot
Where the optic nerve leaves the eye - there are no photoreceptors there
Cones
Photoreceptor dealing with color vision and fine detail. Most effective in bright light. Allows us to see chromatic and achromatic colors. Each cone has its own bipolar cell connection to the brain (“private line”)
Rods
Photoreceptors that only detect achromatic colors (light but no hue). They have low sensitivity to detail and work best in reduced illumination. There are more rods than cones. Rods share a bipolar cell connection to the brain (“party line”)
Fovea
Where visual acuity is best. Only rods in the fovea (as you move away from it, the number of rods decreases and number of cones increases)
Optic Nerve
Comprised of ganglion cells that help link with photoreceptors
Optic Chiasm
Where the nasal fibers cross paths (whereas the temporal fibers do not cross paths)
Where in the Brain Visual Sensory Information is Processed
- Lateral geniculate nucleus of the thalamus
- Visual cortex in the occipital lobe
- Superior colliculus
Feature Detection Theory
Hubel and Wiesel
Certain cells in the cortex are maximally sensitive to certain features of stimuli. Three types of cells:
- Simple (orientation)
- Complex (movement)
- Hypercomplex (shape)
Illumination
A physical, objective measurement of the amount of light falling on a surface
Brightness
The subjective impression of intensity of a light stimulus
Dark Adaptation
A factor in perceiving brightness concerned with adapting to darker environments.
The reason we cannot immediately see in the dark is because the light reaching photoreceptors before entering the dark room bleached the photopigment in the rods (RHODOPSIN). Bleaching = when rhodopsin absorbs light photons and begins to decompose into retinal and opsin (its parts). It takes time to regenerate
Lateral Inhibition
Adjacent retinal cells inhibit one another, which sharpens and highlights borders between light and dark areas
Trichromatic Theory of Color Vision
Young and Helmhotlz
Retina contains three different types of color receptors (cones) which are differentially sensitive to different colors (cones for red, blue, and green). All colors are produced by the combined stimulation of these receptors
Opponent Process Theory of Color Vision
Ewald Hering - came from criticism of Trichromatic Theory
Three opposing pairs (red-green/ blue-yellow/ white-black). Afterimages support this theory
Interposition
A depth cue (aka overlap) - if one object covers another, the partially hidden object is seen as farther away
George Berkeley
Relative Size
A depth cue - Comparison of retinal size of object to actual size of object gives us cues to depth (smaller when farther away)
George Berkeley
Linear Perspective
A depth cue - parallel lines appear to converge as they recede into the distance
George Berkeley
Texture Gradients
A depth cue - as scenes recede from the viewer, the surface texture of the objects seem to change
J. J. Gibson
Motion Parallax
A depth cue - when an observer moves, objects in a stationary environment appear to move relative to the distance from the observer
Binocular Disparity
A depth cue (aka stereopsis) - each eye sees a slightly different scene; when the brain combines the scenes, we get a perception of depth
Gestalt Laws of Form Perception
- Law of proximity (elements close o one another tend to be perceived as a unit)
- Law of similarity (similar elements are grouped together)
- Law of good continuation (elements that appear to follow same direction tend to be grouped together)
- Law of Closure (tendency to see incomplete figures as being complete)
- Law of Prägnanz (Encompasses all other laws and says that perceptual organization will always be as parsimonious as possible)
Theory of Isomorphism
Köhler
There is a one-to-one correspondence between the object in the perceptual field and the pattern of stimulation in the brain (not much empirical support)
Bottom-Up Processing
Theory of Object Recognition: Data driven, sums up components to create a whole
Top-Down Processing
Theory of Object Recognition: Conceptually driven; perception is guided by conceptual patterns (expectations, memories) to recognize objects first, then its components
Five Ways to Make Light Look Like it’s Moving
- Real motion
- Apparent motion (phi phenomenon; when two stationary lights flicker in succession, they’re perceived as a single moving light)
- Induced motion (stationary point of light appears to move when the background moves)
- Autokinetic effect (stationary point of light in a totally dark room appears to move - likely due to involuntary eye movements & no frame of reference)
- Motion aftereffect (if a moving object is viewed for an extended period, a spot of light will appear to move in the opposite direction when the motion stops)
Distal Stimulus vs Proximal Stimulus
Distal = actual object Proximal = sensory information received
Four Constancies if Visual Perception
- Size constancy
- Shape constancy
- Lightness constancy
- Color constancy
Studying Perception in Infants (2 major methods)
- Preferential Looking
2. Habituation
Visual Cliff
Eleanor Gibson and Richard Walk
Studying depth perception in infants
Dimensions of Sound
- Frequency (Objective dimension. Number of cycles per second, measured in Hz)
- Intensity (Objective dimension. Amplitude of sound wave, measured in decibels)
- Pitch (Subjective experience of the frequency of sound)
- Loudness (Subjective experience of intensity of sound)
- Timbre (Refers to the quality of the sound)
Outer Ear
Contains
- Pinna
- Auditory Canal
Pinna
In the outer ear. Channels sound waves into the auditory canal
Auditory Canal
In the outer ear. Channels sound to the eardrum
Middle Ear
Contains three bones/ossicles that transmit vibrations to the inner ear
- Hammer (aka malleus)
- Anvil (aka incus)
- Stirrup (aka stapes)
Inner Ear
Contains
- Cochlea
- Semicircular canals
Coclea
Contains the Basilar Membrane (hair cells are receptors for hearing)
Processing Auditory Sensory Information
Cochlea —> Basilar Membrane (hairs bend) —> transduced into electrical charges —> transmitted out of cochlea along nerve fiber
Brain Structures Relating to Audition
- Superior olive
- Inferior colliculus
- Medial geniculate nucleus in the thalamus
- Temporal cortex
Place Theory of Pitch Perception
Helmholtz
Each different pitch causes a different place on the basilar membrane to vibrate
Frequency Theory of Pitch Perception
Suggests that the basilar membrane vibrates as a whole, and that the rate of vibration equals the frequency of the stimulus (and that the vibration rate is directly translated into the appropriate number of neural impulses per second)
Traveling Wave Theory
Békésky
High frequency sounds maximally vibrate the basilar membrane near the beginning of the cochlea close to the oval window and low frequencies maximally vibrate basilar membrane near the apex/tip of the cochlea
Taste Sensory Receptors
A chemical sense. Receptors = Papillae (in taste buds). Information travels to the taste center in the thalamus
Smell Sensory Receptors
A chemical sense. Receptors = Olfactory epithelium. Information travels to the olfactory bulb.
Four Categories of Touch
- Pressure
- Pain
- Warmth
- Cold
Five Types of Touch Receptors
- Pacinian corpulscles (deep pressure)
- Meissner corpuscles (touch)
- Merkle discs (warmth)
- Ruffini endings (warmth)
- Free nerve endings
Two-Point Thresholds
Minimum distance necessary between two points of stimulation on the skin for the points to be felt as distinct stimuli
Physiological Zero
Neutral body temperature that is perceived to be neither nor nor cold
Gate Theory of Pain
Theory that there is a gating mechanism on the spinal cord that turns pain signals on and off
Proprioception
A term for out sense of bodily sensation
Vestibular Sense
Balance and bodily position relative to gravity (receptors = semicircular canals in the inner ear, behind the cochlea)
Kinesthetic Sense
Awareness of body movement and position (receptors = muscles, tendons, joint)
Brain Structures Relating to Vision
- Lateral geniculate nucleus in the thalamus
- Superior colliculus
- Visual cortex in the occipital lobe
Brain Structures Relating to Touch
Somatosensory cortex in the parietal lobe
Specificity Theory (sensation)
Given neurons fire for given signal qualities
Across-Fiber Theory (sensation)
Quality of signal comes from overall pattern of neural firing
Bipolar Cells
As a part of the retina, bipolar cells exist between photoreceptors (rod cells and cone cells) and ganglion cells. They transmit signals from the photoreceptors to the ganglion cells.
Ganglion Cells
Collect visual information in their dendrites from bipolar cells and amacrine cells and transmit it to the brain
Accommodation
The process by which the vertebrate eye changes optical power to maintain a clear image or focus on an object as its distance varies
