Ch 4 Sensation And Perception Flashcards
What are psychophysics?
The study of how physical stimuli are translated into psychological experience
What is the difference between sensation and perception?
Sensation is the stimulation of sense organs
Perception is the selection, organization, and interpretation of sensory output
What is a threshold?
A dividing point between energy levels that do and do not have a detectable effect- difference threshold
Ie. Turning music up and down till you notice a difference
What is an absolute threshold?
The minimum amount of stimulation that an organism can detect 0—> something
True or false, for an absolute threshold to exist, it must occur 50% of the time
True
What is a just noticeable difference?
The smallest difference in the amount of stimulation that a specific sense can detect.
Eg. Smallest amount of salt you can add to notice difference
True or false, an absolute threshold is the just noticeable difference from nothing
True
Explain the signal detection theory
Proposes that he detection of stimuli involves decision processes as well as sensory processes influenced by a variety of factors
Explain sensory adaptation
A gradual decline in sensitivity due to prolonged stimulation
Eg. Smelly garbage
The smallest amount of tumult ion you can detect is (0—>something)
Absolute threshold
Light waves vary in amplitude, wavelength and purity. Explain what amplitude, wavelength, and purity are.
Amplitude– height
Wavelength– distance between peaks
Purity– how aired the mix of light is
True or false, humans can only perceive the wavelengths of light?
True
what are the two functions of the eye?
to channel light into the neural tissue, and to house that tissue
When referring to the eye, what is the lens?
Transparent eye structure that focuses the light rays falling on the retina
What is the difference between nearsightedness and farsightedness?
nearsightedness– close objects seen clear, far objects seem blurry
farsightedness– far objects seen clear, close objects are seen blurry
When does nearsightedness occur? When does farsightedness occur? What is “wrong” with the eye?
When the cornea bends the light too much (nearsightedness)
When the eyeball is too short
farsightedness
what are saccades?
When the eyes are scanning an environment and making brief fixations
What is the retina?
The neural tissue lining the inside back surface of the eye
What does the retina do?
absorbs light, processes images, and sends visual info to the brain
In the retina, what are the differences of the cones and the rods?
cones– specialized visual receptors that play key roles in daylight vision and colour vision.
Rods– specialized visual receptors that play a key role in night vision and peripheral vision
True or false, the rods and cones on the retina funnel signals to the receptive field
true
What is the receptive field?
he retinal area that when stimulated affects the firing of that cell (for example, the signal towards the brain and nearby cells)
What is lateral antagonism and when does it occur?
occurs when neural activity in a cell opposes activity in surrounding cells , when the excited neuron reduced activity of its neighbours
What is the fovea? (in the retina)
tiny spot in the center of the retina that contains only cones– visual acuity is best here
What is the optic chiasm?
the point at which the optic nerves from the inside of the eye cross over and project to the opposite half f the brain
from the optic chiasm, where do the visual signals travel?
thalamus– brains major relay centre or the
Superior colliculus
what are the main visual pathways that the main visual pathway splits into?
magonocellar and the parvocellar channels
where does most visual input arrive?
the primary visual cortex in the occipital lobe
What do feature detector neurons respond to?
very specific features of more complex stimuli ex. lines, edges, angle or movement
What is visual agnosia?
the inability to recognize objects
What is propagnosia?
the inability to recognize familiar faces
true of false, perceiving colour is a function of dominant wavelengths
true
What colour are the longest wavelengths and what colour are the shortest?
red and violet
What is subtractive colour mixing?
removing some wavelengths of light
leave less light than was originally there
happens when mixing paint (everything turns brown)
What is additive colour mixing?
superimposing light, putting more light in the mixture than exists
Explain the trichromatic theory of colour vision
the human eye has 3 types of receptors with differing sensitivity to different light weave lengths
red, green, and blue
plain the opponent process thoery
colour perception depends on receptors making antagonistic responses to 3 pairs of colours
think= negative colours then looking at a wall and seeing regular colours
what is a perceptual set?
readiness to perceive stimulus in a particular way.. expectations
What is feature analysis?
the process of detecting specific elements and assembling them into more complex ideas or shapes
ex. lines–> 2D shape–> 3D shape
explain the Phi phenonomenon
the illusion of movement created by presenting visual stimulus in rapid succession
ex. movies and tv
what are the two perceiving forms?
bottom up processing ( indiv. to the whole)
top down processing (progression from whole to the elements, ex. big to small.)
Explain distal stimuli
stimuli that lie in the distance outside the body
Explain proximal stimuli
stimulus energies impinge directly on sensory receptors
how do people bridge the gap between distal and proximal stimuli?
by making a perceptual hypothesis
what is a binocular depth?
differing views based on two eyes
What is retinal disparity?
objects projected slightly differently on the retina
what is monocular depth?
distance clues based on image in either eye alone
The Gestalt principles are used to help us…?
organize elements in a scene