Sensation & Perception Flashcards
absolute threshold
the minimum of stimulus energy that is needed to activate a sensory system
difference threshold
how different 2 stimuli (in magnitude) must be before they are perceived to be different
just noticeable difference (jnd)
the amount of change necessary to predict the difference between 2 stimuli
Weber’s Law
ration of absolute difference of 2 stimuli is important in producing a jnd
Fechner’s Law
expresses the relationship between the intensity of the sensation and the intensity of the stimulus
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 front of eye, gathers & focus incoming light
pupil
hole in the iris, contracts in bright light, expands in dim light
iris
colored part- controls size of pupil & amount of light entering eye
lens
lies right behind iris, helps control curvature of the light coming in and can focus new or distant objects on the retina
retina
in the back of the eye and is like a screen filled w/ neural elements and blood vessels –> image detecting part of the eye
cones
- used for Color vision and for perceiving fine detail
- most effective in bright light, and allows us to see chromatic and achromatic colors
rods
- in reduced illumination, function best and allow perception only of achromatic colors
- have low sensitivity to detail and are not involved in color vision
- many more rods than cones
rhodopsin
photo pigment
illumination
a physical, objective measurement that is simply the amount of light falling on a surface
brightness
the subjective impression of the intensity of a light stimulus
color perception
related to the wavelength of the light entering the eye
Young-Helmhotz (Trichromatic Theory)
suggests that the retina contains 3 different types of color receptors (cones), which are differentially sensitive to different colors
Ewald Hering
primary colors arranged in opposing pairs
depth perception
when one object (A) covers or overlaps w/ object (B), we see object (A) as being in front
Perception of Form
- perceptual objects exist only in our mind, and not in the retinal image
- figure: integrated visual experience that stands out at the center of attention
- ground: the background against which the figure appears
Gestalt Laws of Organization- proximity
elements close to one another tend to be perceived as a unit
Gestalt Laws of Organization-similarity
elements that are similar to one another tend to be grouped together
Gestalt Laws of Organization-good continuation
elements that appear to follow in the same direction tend to be grouped together
Gestalt Laws of Organization- closure
the tendency to see incomplete figures as being complete
Gestalt Laws of Organization-pragnanz
perceptual organization will always be as “good” (I.e regular, simple, symmetrical, etc) as possibe
bottom-up processing
(data driven) object perception that responds directly to the components of incoming stimulus on the basis of fixed rules
top-down processing
(conceptually driven) object perception that is guided by conceptual processes such as memories & expectations
Visual Constancies- size constancy
tendency for the perceived size of an object to remain constant despite variation in the size of its retinal image
Visual Constancies- shape constancy
tendency for the perceived shape of an object to remain constant despite variation in the shape of its retinal image
Visual Constancies-lightness constancy
tendency for the perceived lightness of an object to remain constant despite changes in illumination
Visual Constancies- color constancy
tendency for the perceived color of an object to remain constant despite changes in the spectrum of light falling on it
frequency
the # of cycles/second; measured in Hz
intensity
the amplitude of the sound wave; measured in decibels
pitch
the subjective experience of the frequency of the sound
loudness
the subjective experience of the intensity of the sound
timbre
refers to the quality of the sound
