Sensation & Perception Flashcards
Difference threshold
The amount of stimulus energy that needs to be added to or subtracted from a stimulus for a person to say that she notices a difference
Absolute threshold
The amount of stimulus energy needed for a person to say that she perceives it.
JND
One jnd needs to be added to or subtracted from a stimulus for a person to say that she notices the difference.
Weber’s law
What’s important in producing a jnd is not the absolute difference btw the 2 stimuli, but the ratio of them. Fechner.
Fechner’s law
Relates the intensity of the stimulus to the intensity of the sensation. Sensation increases more slowly as intensity increases
Steven’s power law
Also relates intensity of stimulus to intensity of sensation. Stevens performed some experiments that did not fit w fechner’s law, but instead fit this equation.
Response bias
Measures how risky the subject is in sensory decision making; based upon nonsensory factors
Sensitivity
Measures how well the subject can sense the stimulus
ROC curve
Used to graphically summarize a subject’s responses in a signal detection experiment. John A. Swets refined the use of ROC curves
Signal detection theory
Gives us a way to measure both sensitivity and response bias. Hit, miss, false alarm and correct rejection
Commonalities of sensory systems
Receptors- respond to physical stimuli
Transduction- translates physical energy to neural impulses
Projection areas- brain areas that further analyze sensory input
Cornea
Clear, domelike window in the front of your eye which gathers & focuses the incoming light
Pupil
The hole in the iris. Contracts and dilates in bright & dim light
Iris
The colored part of the eye. Involuntary muscles. It controls the size of the pupil, and therefore, the amount of light that enters the eye
Lens
Lies right behind the iris. Helps control the curvature of the light coming in and can focus near or distant objects on the retina
Retina
In the back of the eye & is like a projection screen that detects images. Image appears upside down on Retina
Duplicity theory of vision
States that the retina contains two kinds of photoreceptors- rods & cones (light must first pass through intermediate sensory neurons b4 reaching photoreceptors).
Cones
Used to detect fine detail & color vision. Most effective in bright light. In the center of the eye is the fovea- contains only cones. As you move away from center, # of cones decrease
Rods
Fxn best in dim light & only perceive achromatic colors. Not involved in color, low sensitivity to detail. More Rods than cones, at periphery, only rods
Connection btw receptors and optic nerve
Rods & cones➡️bipolar neurons ➡️ganglion cells (form optic nerve). The greater the number of receptors that converge onto one ganglion cell, the more difficult it is to see fine detail
Optic chiasm
Here the fibers from the nasal half of the retina cross paths. The fibers from the temporal halves do not cross paths on way to brain.
Where visual info goes when it leaves brain
Lateral geniculate nucleus of the thalamus, the visual cortex in the occipital lobe, and the superior colliculus.
Hubel & Wiesel work on visual cortex
Feature detection theory. Certain cells are maximally sensitive to certain stimuli: simple- orientation, complex- movement, and hypercomplex- shape
Brightness perception
Illumination- objective measurement of light.
Brightness- subjective impression of intensity
Dark adaptation
Caused by the regeneration of rhodopsin, the photopigment in the rods
Lateral inhibition
Adjacent retinal cells inhibit one another; sharpens and highlights borders between light and dark areas
Subtractive color mixture
Occurs when we mix pigments. Blue + yellow make green
Additive color mixing
Occurs when we mix lights. Primary colors are blue, green (not yellow) & red. Red + green= yellow
Young-Helmholtz (trichromatic)
Three types of color receptors that are differentially sensitive to primary colors red, blue, green. Research has shown this theory to be the correct one
Hering (opponent process)
Three opposing pairs: red- green, blue-yellow, black-white. The concept of afterimages led him to his theory.
Interposition (overlap)
When an object covers another object, we see it as being in front. George berekley
Relative size
Another cue for depth perception. If u know something about actual size, u can tell how far away something is by how large it appears.
Linear perspective
Refers to the convergence of parallel lines in the distance
J.J Gibson
Texture gradients. As scene recedes from viewer, the surface texture appears to change.
Motion parallax
Looking out a car window. Speed at which objects appear to move. Kinetic depth effect- when an object rather than the perceiver moves, the motion gives us cues about relative depth
Binocular disparity (stereopsis)
Only cue that requires two eyes. When brain combines two views from each eye, we get a perception of depth
Gestalt- proximity
Elements close to one another tend to be perceived as a unit
Gestalt- similarity
Elements that are similar to one another tend to be grouped together
Gestalt- Good continuation
Elements that appear to follow in the same direction tend to be grouped together
Gestalt- Closure
The tendency to see incomplete figures as being complete
Gestalt- subjective contours
Perceiving contours, and therefore shapes, that are not present in the physical stimulus
Prägnanz
Perceptual organization will always be as regular or simple as possible
Theory of isomorphism
There is a 1:1 correspondence btw the object in the perceptual field and the pattern of stimulation in the brain. Hasn’t fared well empirically
Bottom up processing (data driven)
Responds directly to components of incoming stimuli on the basis of fixed rules and then sums up components to arrive at the whole pattern
Top- down processing (conceptually driven)
Guided by conceptual processes such as memories and expectations that allow the brain to recognize whole objects and then components
Apparent motion (phi phenomenon)
When two or more stationery lights flicker in succession they tend to be perceived as a single moving light
Induced motion
A stationery point of light appears to move when the background moves
Autokinetic effect
A stationery point of light when viewed in a dark room appears to move; probably caused by involuntary eye movement & no frame of reference
Motion aftereffect
If a moving object is viewed for an extended period of time (waterfall), it will appear to move in an opposite direction when the motion stops
Emmert’s Law (size- distance invariance principle)
Size constancy depends on apparent distance.
Ames room
Through peephole, room appears to be a rectangular room, but really it is a trapezoid; therefore, a person one on side will appear much bigger than a person on right bc we have been fooled into believing that the difference of visual angles is not due to size
Moon illusion
Moon appears larger at horizon than at its zenith (perhaps bc of distance cues like bldgs)
Size constancy
Tendency for the perceived size of an object to remain constant despite variations in the size of its retinal image
Shape constancy
Tendency for perceived shape of an object to remain constant despite variations in the shape of its retinal image
Lightness constancy
Tendency for the perceived lightness of an object to remain constant despite changes in illumination
Color constancy
Tendency for the perceived color of an object to remain constant despite changes in the spectrum of light falling on it
Muller-Lyer illusion
Line with arrows pointing out look smaller than line with arrows pointing in- even though the are same length
Ponzu illusion
Two lines within an inverted triangle are same size, even though the line closer to the point looks larger
Hering & Wundt illusions (different)
The two horizontal lines are straight & parallel although they don’t appear that way
Poggendorf illusion
The diagonal line on bottom is a continuation of the diagonal line on the top
Reversible figure
A stimulus pattern in which two alternative, equally compelling perceptual organizations spontaneously oscillate. I.e Necker cube
Preferential looking
Two different stimuli are presented side by side; if infant looks longer at one of them, it is inferred that the infant can perceive the difference btw the stimuli
Habituation
A stimulus is presented to infant, infant eventually stops attending to it; a different stimulus is presented; if infant attends to it, it is inferred that the infant can perceive the difference btw the old and new stimuli
Visual cliff
An apparatus designed by Gibson and Walk to assess infant depth perception
Animal experiments
Sometimes used to assess contributions of nature and nurture to the development of vision
Frequency
Objective dimension of sound. The number of cycles per second; measured in Hertzes
Intensity
Objective measure of sound. The amplitude of to the sound wave; measured in decibels
Pitch
The subjective experience if the frequency of the sound
Loudness
The subjective experience of the intensity of the sound
Timbre
Refers to the quality of the sound (I.e piano vs. clarinet)
Pinna
Outer ear. Fleshy part of the ear visible from the outside. Main fxn is to channel sound waves into the auditory canal.
Eardrum (tympanic membrane)
Auditory canal channels the sound here. Vibrates in phase with the incoming sound waves.
Middle ear
Has 3 tiny bones called ossicles, which are the smallest bones in your body, & transmit the vibrations of the tympanum to the inner ear
Cochlea
Inner ear. Filled with cochlear fluid. Contains basilar membrane & organ of Corti (where transduction takes place)- the hair cells on this are the receptors for hearing. Works like a chain rxn
Auditory nerve
Gets signals from nerve fibers from bending hair cells. Then projects to the superior olive, the inferior colliculus, and the medial geniculate nucleus in the thalamus, and finally to the temporal cortex
Place theory
Operative for tones btw 500- 4,000 HzHelmholtz and Young. Each diff pitch causes a different place on the basilar membrane to vibrate. These different places of disturbance cause different hair cells to bend
Frequency theory
Operative for tones up to 0-4000 Hz. Basilar membrane vibrates as a whole, and that the rate of vibration equals the frequency of the stimulus. Translates to a proportional number of neural impulses per second.
Beskey’s traveling wave theory
High frequencies maximally vibrate the membrane near the part of the cochlea close to the oval window; low frequencies maximally vibrate near the tip of the cochlea
Taste & Smell
Chemical senses- receptors require contact w molecules that make up the stimulus.
Taste- taste buds- papillae. Travels to taste center in thalamus.
Smell- receptors in the upper nasal passage of nose called olfactory epithelium. Travels to olfactory bulb in brain.
Touch
Pressure, pain, warmth & cold. Info travels to somatosensory cortex in parietal lobe.
Two-point threshold
The minimum distance necessary btw two points of stimulation on the skin such that the points will be felt as 2 distinct stimuli
Physiological zero
A neutral temperature perceived to be neither not not cold.
Gate theory of pain
The theory that there is a gating mechanism in the spinal cord that turns pain signals on and off
Proprioception
Our sense of bodily position and includes aspects of both vestibular and kinesthetic senses
Vestibular sense
Our sense of balance and body position relative to gravity
Kinesthetic sense
Awareness of body movement and position; specifically with muscle, tendon, and joint position
Dichotic listening
Selective attention. Two ears are presented with 2 diff messages. Listeners can attend to one message and dampen out the other
Yerkes- Dodson law
Performance is worst at extremely low or extremely high levels of arousal & optimal at some intermediate level.
Physical vs. psychological properties
Physical- objective
Psych- subjective
