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Sensation and Perception
n/a
58
Psychology
Undergraduate 3
05/05/2013

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Term
absolute threshold
Definition
the smallest amount of stimulus energy necessary to detect a stimulus
Term
classical psychophysical methods
Definition
the original methods used to measure the relationship between sensation and perception
Term
difference threshold
Definition
the smallest difference between two stimuli that a person can detect (DL); size of DL is dependent on the size of the standard weight
Term
magnitude estimation
Definition
a psychophysical method in which a subject assigns numbers to a stimulus that are proportional to the subjective magnitude of the stimulus
Term
method of constant stimuli
Definition
the experimenter presents 5-9 stimuli with different intensities in random order; the threshold is the intensity that is detected 50 percent of the time
Term
method of adjustment
Definition
the experimenter adjusts the intensity of the stimulus in a continuous manner until the subject can just barely detect a stimulus (this is the absolute threshold)
Term
method of limits
Definition
experimenters present stimuli in either ascending or descending order and a change in response is the threshold
Term
psychophysics
Definition
any measurement of the relationship between sensation and perception
Term
response compression
Definition
when doubling the physical intensity of a stimulus less than doubles the subjective magnitude of the stimulus (this occurs with lights)
Term
response expansion
Definition
when the doubling the physical intensity of a stimulus more than doubles the subjective magnitude of the stimulus (this occurs with pain becuase this is adaptive)
Term
response criterion
Definition
the subjective magnitude of a stimulus above which the subject will indicate that the stimulus is present
Term
signal detection theory
Definition
a theory stating that the detection of a stimulus depends on both the subject's sensitivity and the subject's response to the criterion.  This gives us a method for creating the sensitivity curve; the purpose is to separate bias and sensitivity.  concerns false alarms and correct rejections.  isosensitivity curve.
Term
steven's power law
Definition
law concerning the relationship between physical intensity of a stimulus and a person's perception of it's magnitude
Term
weber's fraction
Definition
just noticable difference divided by the standard K
Term
weber's law
Definition
law that states that the difference threshold equals the constant K times the size of the stimulus (S).  so, the difference threshold gets bigger as the size of an initial stimulus gets bigger
Term
action potential
Definition
a rapid increase in positive charge in a nerve fiber that is propogated down a fiber
Term
axon
Definition
sends messages of a neuron
Term
cell body
Definition
contains nucleus and other cell structures
Term
center surround receptive field
Definition
a receptive field that consists of a roughly circular excitatory area surrounded by an inhibitory area, or vice versa
Term
center surround antagonism
Definition
an effect that is caused by the fact that the center and surround of a receptive field respond in opposite ways.  center surround antagonism comes into play when a spot of light becomes large enough that it also begins to cover the inhibitory area.  stimulation of the inhibitory area counteracts the center's excitatory response, causing a decrease in firing rate.  This process of sending inhibitory signals across the retina is called lateral inhibition.
Term
dendrites
Definition
receive information
Term
microelectrode
Definition
thin piece of wire or glass that is small enough to record electrical activity from single nerve fibers
Term
doctrine of specific nerve energies
Definition
different nerve signals correspond to different senses; the type and quality of perception depends on the kind of nerve that is activated
Term
primary receiving areas
Definition
area of the cerebral cortex that first receives most of the signals from sense receptors
Term
receptive field
Definition
the area of the retina that, when stimulated, influences the firing rate of a ganglion cell
Term
spontaneous activity
Definition
activity that occurs without sensory input
Term
modular organization of the brain
Definition
specific functions are served by specific areas of the cortex (sight in occipital, hearing in temporal, etc)
Term
what is the mind/body problem?  what is the difference between the hard and easy problem of consciousness?
Definition

the mind body problem is the question of how do physical processes such as nerve impulses (the body part) become transformed into the richness of perceptions (the mind part).

the hard problem is "how do physiological processes turn into experiences"

the easy problem is defining a neural correlate of consciousness (connections between stimuli and environment).

Term
absorption spectrum
Definition
a plot of the amount of light absorbed by a visual pigment versus the wavelength of light
Term
accommodation
Definition
the eye's ability to bring objects located at different distances into focus by changing the shape of the lens
Term
amacrine cells
Definition
neurons that transmit signals laterally in the retina; they synapse with bipolar and ganglion cells
Term
blind spot
Definition
where the optic nerve leaves the eye; no visual receptors here
Term
cones
Definition
cone shaped receptors in the eye that are responsible for vision in high levels of illumination, color vision, and detail vision
Term
cornea
Definition
shapes and focuses the light
Term
dark adaptation
Definition
visual adaptation that occurs in the dark; during which the sensitivity to light increases
Term
dark adaptation curve
Definition
the function that traces the time course of the increase in visual sensitivity that occurs during dark adaptation
Term
electromagnetic spectrum
Definition
continuum of electromagnetic energy that extends from short (gamma) rays to long (radio) waves
Term
fovea
Definition
center area of the retina; covered in cones, located in the line of sight
Term
ganglion cells
Definition
neurons in the retina that receive input from bipolar and amacrine cells; the axons of the ganglions compose the optic nerve that travels to the LGN
Term
Hermann grid
Definition
a geometric display that results in the illusion of dark areas at the intersection of two white corridors; this is explained by lateral inhibition
Term
horizontal cell
Definition
a neuron that transmits signals laterally across the retina
Term
lateral inhibition
Definition
inhibition that is spread laterally across a nerve circuit; spread by horizontal and amacrine cells
Term
monochromatic light
Definition
light that contains a single wavelength
Term
optic nerve
Definition
bundle of nerve fibers that carry impulses from the retina to the LGN and other structures; each optic nerve contains 1 million ganglion fibers
Term
presbyopia
Definition
the inability of the eye to accommodate due to the hardening of the lensand a weakening of the cillary muscles as we age
Term
pupil
Definition
hole in the center of the eye
Term
retina
Definition
a complex network of cells that cover the inside back of the eye.  cells include receptors horizontal, bipolar, amacrine, and ganglion cells.
Term
rod
Definition
rod shaped receptor in the retina responsible for vision at low levels of illumination; sensitive in dark but can't resolve fine details
Term
simultaneous contrast
Definition
the change in perception of color that occurs when a colored field is surrounded by a differently colored background
Term
spectral sensitivity curve
Definition
the function relating a subject's sensitivity to a wavelength of light
Term
visual acuity
Definition
the ability to see fine details
Term
wavelength
Definition
the distance between of one peak of a light wave and the next
Term

Describe the structure of the eye and how moving an object closer to the eye affects how light entering the eye is focusing on the retina.

Definition

-light enters the eye through the pupil

-the cornea and the lens focus the light on the retina

-the cornea accounts for 80% of the eye's focusing power, but it;s fixed in place, so it can't adjust its focus

-the lens accounts for the remaining 20% of the focusing power, since it can adjust and change its shapeto adjust the eye's focus for stimuli located at different distances

-if light is more than 20 feet away, the light rays that reach each eye are essentially parallel, and these parallel rays are brought to focus in the back of the retina at point A.  if it moves closer, it puts focus point behind the retina.  however, if light is stopped before it can get to this point, the image on the retina is out of focus.  accomodation keeps this from happening.  the cillary muscles in front of the eye tighten and increase curvature of the lens so it gets thicker; this increased curvature bends the light rays passing through the lens to pull the focus point back to point A and create a sharp image on the retina.

Term
what happens to visual pigment molecules when they a) absorb light and b) regenerate?  whatis the connection  between visual pigment generation and dark adaptation?
Definition

absorb light- the visual pigment molecules become ligher in color

regenerate- they become darker in color

visual pigment molecules regenerate in the dark

Term
"what" pathway
Definition
the ventral pathway
Term
"where" pathway
Definition
the dorsal pathway
Term
fusiform face area
Definition
area in the human IT cortex that contains neurons that are specialized to respond to faces
Term
double dissociation
Definition
in brain damage, when function A is present but function B is absent; this shows that two functions involve different mechanisms and operate independently of one another
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