Sensation and Perception Flashcards
first researcher interested in individual differences
Galton
founder of Gestalt psychology
Wertheimer
Measuring the relationship between physical stimuli and psychological responses to the stimuli
Psychophysics
Absolute Thresholds
Minimum of stimulus energy that is needed to activate a sensory system
perception of a stimuli below a threshold that occurs without conscious awareness
Subliminal perception
How different two stimuli (in magnitude) must be before they are perceived to be different
Difference Thresholds
Just noticeable difference (JND)
amount of change necessary to predict the difference between two stimuli
Weber’s law
change in stimulus intensity needed to produce a JND divided by the stimulus intensity of the standard stimulus is a constant; ratio is more important than absolute difference
Fechner’s law
sensation increases more slowly as intensity increases
Steven’s power law
criticism of Fechner
Signal Detection Theory
Other, nonsensory factors influences what the subject says they sense
Response bias
tendency of subjects to respond in a particular way due to nonsensory factors
graphically summarize a subject’s response in a signal detection experiment; Swets
Receiver operating characteristic (ROC) curve
Reception
first step in all sensory information processing; receptors that react to physical external energy
Transduction
translation of physical energy into neural impulses or action potentials
clear, domelike window in the front of eye, gathers and focuses incoming light
Cornea
hole in the iris, contracts and dilates
Pupil
colored part of the eye, contains involuntary muscles and autonomic nerve fibers; controls the size of the pupil
Iris
behind the iris, helps control the curvature of light and can focus near or distant objects
Lens
back of the eye, screen filled with neural elements and blood vessels, image-detecting
Retina
Duplexity (duplicity theory of vision)
retina contains two kinds of photoreceptors
Cones
color vision and perceiving fine detail; most effective in bright light
Rods
allow perception of achromatic colors in reduced illumination; low sensitivity to detail and not involved in color
Fovea
in middle of retina; contains only cones
Optic chiasm
fibers from the nasal half of the brain cross paths
information from the eye goes to opposite side of brain
Nasal fibers
information from the eye goes to same side of brain
Temporal fibers
certain cells in the cortex are maximally sensitive to certain features of stimuli
Feature detection theory
give information about the orientation and boundaries of an object
Simple cells
more advanced information about orientation, such as movement
Complex cells
abstract concepts such as object shape
Hypercomplex cells
Illumination
physical, objective measurement that is simply the amount of light falling on a surface
Brightness
subjective impression of the intensity of a light stimulus
Rhodopsin
photopigment found in rods
target area of a particular luminance appears brighter when surrounded by a darker stimulus than when surrounded by a lighter stimulus
Simultaneous brightness contrast
adjacent retinal cells inhibit one another; sharpens and highlights the borders between dark and light areas
Lateral inhibition
mix pigments; yellow, blue, red
Subtractive color mixture
lights; blue green, red
Additive color mixing
Trichromatic theory
retina contains three different types of color receptors; Young-Helmhotz
Opponent-process theory of color vision
four primaries are arranged in opposing pairs, so that one opponent process would signal the presence of red or green, and another would signal the presence of blue or yellow; Hering
Afterimages
visual sensation that appears after prolonged or intense exposure to a stimulus
when one object covers or overlaps with another we see one object as being in front
Interposition (overlap)
as an object gets farther away, its image on the retina gets smaller
Relative size
convergence of parallel lines in the distance
Linear perspective
variations in perceived surface texture as a function of the distance from the observer
Texture gradients (Gibson)
when observer moves, objects in a stationary environment appear to move relative to distance from observer
Motion parallax
when an object rather than the perceiver moves
Kinetic depth effect
Binocular disparity (stereopsis)
distance between the eyes provides us with two slightly dsparate views on the world
Binocular parallax
degree of disparity between the retinal images of the eyes due to the slight differences in the horizontal position of each eye in the skull
integrated visual experience that stands out at the center of attention
Figure
background against which the figure appears
Ground
Law of proximity
elements close to one another tend to be perceived as a unit
Law of similarity
objects that are similar tend to be grouped together
Law of good continuation
elements that appear to follow in the same direction tend to be grouped together
Subjective contours
perceiving contours that are not present in the physical stimulus
Law of closure
when a space is enclosed by a contour it tends to be perceived as a figure
Law of Pragnanz
create the most stable, consistent, and simple figures possible within a given retinal array
there is a one-to-one correspondence between the object in the perceptual field and the pattern of stimulation in the brain
Theory of isomorphism (Kohler)
object perception that responds directly to the components of incoming stimulus on the basis of fixed rules
Bottom-up processing
object perception that is guided by conceptual processes such as memories and expectations that allow the brain to recognize the whole object and then recognize the components
Top-down processing
Real motion
actually moving light
Apparent motion (stroboscopic movement or phi phenomenon)
illusion that occurs when two dots flashed in different locations on a screen seconds apart are perceived as one moving dot
Induced motion
illusion of movement occurring when everything around the spot of light is moved
Motion aftereffect (waterfall illusion)
when you first view a moving pattern and then you view a spot of light: the spot of light will appear to move in the opposite direction
actual object or event out there in the world
Distal stimulus
information our sensory receptors receive about the object
Proximal stimulus
tendency for the perceived size of an object to remain constant despite variations in the size of its retinal image
Size constancy
tendency for the perceived shape of an object to remain constant despite variations in the shape of its retinal image
Shape constancy
despite changes in the amount of light falling on an object, the apparent lightness of the object remains unchanged
Lightness constancy
perceived color of an object does not change when we change the wavelength of the light we see
Color constancy
Muller-Lyer and Ponzo Illusions
two horizontal lines are the same length
Hering and Wundt Illusions
two horizontal lines are straight and parallel
Poggendorff Illusion
diagonal line on bottom is continuation of diagonal on the top
Preferential looking
if infant looks longer at one of two presented stimuli, it can be inferred that the infant can perceive the difference between the stimuli; Fantz
Habituation
when a new stimulus is presented to an infant, the infant will orient toward it
number of cycles per second measured in Hertz
Frequency
amplitude or height of the air-pressure waves measured in bels
Intensity
subjective experience of the magnitude or intensity of the sound
Loudness
subjective experience or perception of the frequency of the sound
Pitch
quality of a particular sound
Timbre
Pinna
fleshy part of the ear that channels sound waves into the auditory canal
Eardrum (tympanic membrane)
vibrates in phase with the incoming sound waves
Oval window
entrance to the inner ear
Basilar membrane
membranes that run the length of the cochlea
Organ of Corti
composed of thousands of hair cells that are receptors for hearing
each different pitch causes a different place on the basilar membrane to vibrate
Place theory (Helmholtz and Young)
basilar membrane vibrates as a whole, and that the rate of vibration equals the frequency of the stimulus which is then directly translated into the appropriate number of neural impulses per second
Frequency theory
movement of the basilar membrane is maximal at a different place along the basilar membrane for each different frequency
Bekesy’s Traveling Wave
minimum distance necessary between two points of stimulation on the skin such that the points will be felt as two distinct stimuli
Two -point theory
Physiological zero
temperature of the skin
Gate theory of pain
there is a special “gate” mechanism that can turn pain signals on and off; Melzack and Wall
Proprioception
sense of bodily position
Vestibular sense
sense of balance and of our bodily position relative to gravity
Kinesthetic sense
awareness of body movement and position
acts as a filter between sensory stimuli and our processing systems
Selective attention
performance is worst at extremely low or extremely high levels of arousal
Yerkes-Dodson Law
