Sensation & Perception - Lecture 3

Question 1

Contrast

Answer 1

The difference in luminance between an object and the background, or between lighter and darker parts of the same object.

Question 2

Acuity

Answer 2

The smallers spatial detail that can be resolved at 100% contrast.

Question 3

Cycle

Answer 3

For a grating, a pair consisting of one dar bar and one bright bar.

Question 4

Visual angle

Answer 4

The angle subtended by an object at the retina.

Question 5

Sine wave grating

Answer 5

A grating with sinusoidal luminance profile.

Question 6

Amblyopia

Answer 6

A developmental disorder characterized by reduced spatial vision in an otherwise healthy eye, even with proper correction for refractive error. Also known as lazy eye.

Question 7

Spatial frequency

Answer 7

The number of grating cycles per unit of visual angle in a given unit of space.

Question 8

Cycles per degree

Answer 8

The number of grating cycles per degree of visual angle.

Question 9

Contrast sensitivity function (CSF)

Answer 9

A function describing how the sensitivity to contrast depends on the spatial frequency of the stimulus.

Question 10

Contrast threshold

Answer 10

The smallest amount of contrast required to detect a pattern.

Question 11

Fourier analysis

Answer 11

A mathematical procedure by which any signal can be separated into component sine waves at different frequencies. Combining the sine waves will reproduce the original signal.

Question 12

Phase

Answer 12

The position of a grating relative to a fixed position measured in degrees, where one complete cycle is 360 degrees.

Question 13

Filer

Answer 13

An acoustic, electrical, electronic, or optical device, instrument, computer program, or neuron that allows the passage of some range of parameters and blocks the passage of others.

Question 14

Lateral geniculate nucleus (LGN)

Answer 14

A structure in the thalamus, part of the midbrain, that receives input form the retinal ganglion cells and has input and outputs connections to the visual cortex.

Question 15

Magnocellular layer

Answer 15

Either of the bottom two neuron-containing layers of the lateral geniculate nucleus, the cells of which are physically larger than those in the top four layers.

Question 16

Parvocellular layer

Answer 16

Any of the top fout neuron-containing layers of the lateral geniculate nucleus, the cells of which are physically smaller than those in the bottom two layers.

Question 17

Koniocellular cell

Answer 17

A neuron located between the magnocellular and parvocellular layers of the lateral geniculate nucleus. This layer is known as the koniocellular layer.

Question 18

Contralateral

Answer 18

Referring to the opposite side of the body or brain.

Question 19

Ipsilateral

Answer 19

Referring to the same side of the body or brain.

Question 20

Topographical mapping

Answer 20

The orderly mapping of the world in the lateral geniculate nucleus and the visual cortex.

Question 21

Primary visual cortex (V1), area 17, or striate cortex

Answer 21

The area of the cerebral cortex of the brain that receives direct inputs from the lateral geniculate nucleus, as well as feedback from other brain ares.

Question 22

Cortical magnification

Answer 22

The amount of cortical area devoted to a specific region in the visual field.

Question 23

Eccentricity

Answer 23

The angular distance from the fovea.

Question 24

Visual crowding

Answer 24

The deleterious effect of clutter on peripheral object recognition.

Question 25

Orientation tuning

Answer 25

The tendency of neurons in striate cortex to respond optimally to certain orientations and less to other.

Question 26

Ocular dominance

Answer 26

The property of the receptive fields of striate cortex neurons by which they demonstrate a preference, responding somewhat more rapidly when a stimulus in presented in one eye than when it is presented in the other.

Question 27

Simple cell

Answer 27

A cortical neurons whose receptive field has clearly defined excitatory and inhibitory regions.

Question 28

Complex cell

Answer 28

A cortical neuron whose receptive field does not have clearly defined excitatory and inhibitory regions.

Question 29

End stopping

Answer 29

The process by which a cell in the cortex increases its firing rate as the length of a bar increases until the bar fills up its receptive field, and then it decreases its firing rate as the bar is lengthened further.

Question 30

Column

Answer 30

A vertical arrangement of neurons. Neurons within a single. column thend to have similar receptive fields and similar orientation prefernces.

Question 31

Hypercolumn

Answer 31

A 1mm block of striate cortex containing two sets of columns, each covering every possible orientation, with one set preferring input from the left eye and one set preferring input from the right eye.

Question 32

CO blobs

Answer 32

Regular arrays of "blobs" spaced about 0.5mm apart in the striate cortex(V1), so named because their presence is visualized by staining with the enzyme cytochrome oxidase(CO) . They may function in color perception.

Question 33

Adaptation

Answer 33

A reduction in response caused by prior or continuing stimulation.

Question 34

Tilt aftereffect

Answer 34

The perceptual illusion of tilt, produced by adaptation to a pattern of a given orientation.

Question 35

Spatial-frequency channel

Answer 35

A pattern analyzer, implemented by an ensemble of cortical neurons, in which each set of neurons is tuned to a limited range of spatial frequencies.

Question 36

Critical period

Answer 36

A phase in the life span during which abnormal early experience cal alter normal neuronal development.

Question 37

Strabismus

Answer 37

A misalignment of the two eyes such that a single object in space is imaged on the fovea of one eye and on a nonfoveal area of the other (turned) eye.

Question 38

Anisometropia

Answer 38

A condition in which the two eyes have different refractive errors.