Deck 5: Seeing Pattern and Motion

Question 1

According to Fourier theory, the frequency component of a square wave with the highest amplitude is the:

A) Third harmonic
B) Fundamental
C) Fifth harmonic
D) Residual

Answer 1

B

Question 2

The peak of the contrast sensitivity function for stationary gratings in moderate luminance occurs at about:

A) The lowest spatial frequency tested
B) 20 c deg⁻¹
C) 5 c deg⁻¹
D) 0.5 c deg⁻¹

Answer 2

C

Question 3

By how many spatial channels did Wilson et al. suggest foveal stimuli were encoded?

A) 12
B) 2
C) 3
D) 6

Answer 3

D

Question 4

Why does adaptation to square-wave gratings provide a strong test of the theory that spatial vision includes a Fourier analysis?

A) The theory predicts threshold elevation of sinusoidal gratings with frequencies of the third and fifth harmonics
B) The theory predicts threshold elevation of a sinusoidal grating of the fundamental frequency
C) The theory predicts a phase shift of the higher harmonics
D) The theory predicts no threshold elevations for lower spatial frequencies

Question 5

Which of these phenomena suggests interactions between spatial channels?

A) Threshold elevation of gratings similar in spatial frequency to the adapting grating
B) The simultaneous spatial frequency illusion
C) The shape of the contrast sensitivity function
D) None of these

Question 6

Squaring is a useful procedure in modelling because it:

A) Expands the range of values to be processed
B) Removes very small numbers from the range of values to be processed
C) Converts negative numbers to positive numbers
D) Mimics the activity of nerve cells

Question 7

Computation of which of the following has not been suggested as a method of edge location:

A) First derivative
B) Second derivative
C) Third derivative
D) Fifth derivative

Question 8

Holway and Boring's study suggested that:

A) Perceived size varies with perceived distance
B) There is no systematic relationship between perceived size and perceived distance
C) Perceived size influences perceived distance
D) Perceived distance is difficult to measure

Question 9

Leibowitz and Harvey's study suggested that the process underlying size constancy is:

A) Automatic
B) Subject to large random variation
C) Fast
D) Flexible

Question 10

'Retinal size' is probably:

A) Sensed directly
B) Computed from perceived distance and perceived size
C) Dependent on binocular vision
D) Dependent on retinal location

Question 11

In the Barlow and Levick model of a motion detector, two inputs are compared in a:

A) NOR gate
B) AND gate
C) AND NOT gate
D) NAND gate

Question 12

In an x-t plot of a moving stimulus, velocity is given by:

A) Position on the y-axis
B) Position on the x-axis
C) The slope
D) The intercept

Question 13

Cinema is possible because motion detectors:

A) Are sluggish
B) Are sensitive to colour
C) Work in dim light
D) Sample the trajectories of moving objects

Question 14

First-order motion detectors respond to moving patterns defined by:

A) Luminance
B) Contrast
C) Depth
D) Size

Question 15

The minimum stimulus change of a second-order moving pattern which can be detected in a range of conditions corresponds to:

A) A minimum velocity
B) A minimum change of contrast
C) A minimum displacement
D) A minimum change in depth

Question 16

Vaina and Soloviev suggested that second-order motion is processed within the:

A) Dorsal stream
B) Cerebellum
C) Hippocampus
D) Ventral stream

Question 17

Ramachandran and Anstis suggested that false matches were avoided in the perception of random dot kinematograms by:

A) Initial matching of low spatial frequencies
B) Tracking by small eye movements
C) Initial matching of high spatial frequencies
D) Finding a maximum displacement

Question 18

Which stimulus manipulation did Braddick find to cause loss of perception of motion in random dot kinematograms?

A) Reducing the contrast
B) Presenting the two frames dichoptically
C) Increasing dot size
D) Increasing stimulus area

Question 19

d_max in random dot kinematograms varies with:

A) Dot density
B) Stimulus area
C) Stimulus contrast
D) Monocular vs binocular viewing

Question 20

When two patterns of dots moving horizontally in opposite directions are superimposed, they may produce motion transparency. Which characteristics of the patterns produce transparency?

A) The dots in each pattern must move at the same speeds
B) The patterns must be of the same size
C) The dots in each pattern must have the same lifetime
D) The dots on one pattern must be vertically displaced from the dots in the other

Question 21

Campbell and Robson found that, as their contrasts were increased, a low contrast square-wave grating could be discriminated from a low contrast sine-wave grating when:

A) The fifth harmonic of the square-wave grating reached its contrast threshold
B) Both gratings reached 20% contrast
C) The third harmonic of the square-wave grating reached its contrast threshold
D) Only if spatial frequency was lower than 2 c deg⁻¹

Question 22

The progressive loss of sensitivity to gratings as spatial frequency is decreased below about 5 c deg⁻¹ is probably due to:

A) Lateral inhibition
B) Spatial summation
C) Spatial frequency adaptation
D) Eye movements

Question 23

What was the spatial frequency of the highest spatial frequency channel suggested by Wilson et al. to encode foveal stimuli?

A) 30 c deg⁻¹
B) 16 c deg⁻¹
C) 40 c deg⁻¹
D) 25 c deg⁻¹

Question 24

When they used a forced choice test procedure, Nachmias et al. found, after adaptation to a square-wave grating:

A) Threshold elevation of a sine-wave grating of a frequency of the fifth harmonic of the adaptor
B) No threshold elevation of a sine-wave grating of a frequency of the fundamental of the adaptor
C) No threshold elevation of a sine-wave grating of a frequency of the third harmonic of the adaptor
D) Threshold elevation of a sine-wave grating of a frequency of one-third of the fundamental frequency of the adaptor

Question 25

Which of the following has not been suggested as a cue for edge location?

A) The peak in the first spatial derivative
B) The zero-crossing in the second spatial derivative
C) The peak in the third spatial derivative
D) A trough in the third spatial derivative

Question 26

Holway and Boring's study suggested that:

A) Size constancy may be achieved through an automatic process
B) There is no consistent relationship between depth and retinal size in size constancy
C) Observer motion is important in size constancy
D) Size constancy is best indoors

Question 27

A Reichardt detector signals, in response to flicker:

A) Leftwards and rightwards motion in alternation
B) Nothing
C) Random activity
D) Acceleration

Question 28

The minimum stimulus change of a first-order moving pattern which can be detected in a range of conditions corresponds to:

A) A minimum velocity
B) A minimum change of contrast
C) A minimum displacement
D) A minimum change in depth

Question 29

Motion capture is the:

A) Breakdown in apparent motion in random dot kinematograms as d_max is increased
B) Breakdown in motion transparency as the vertical displacement of dots in horizontally moving patterns is reduced
C) Action of neurons in V5/MT on inputs from V3
D) Induction of motion in the same direction of stationary regions by moving regions of a display

Question 30

From their studies of the perception of moving gratings from which the fundamental had been removed, Georgeson and Shackleton suggested that:

A) Monocular motion detectors are sluggish
B) Binocular motion detectors track features
C) Monocular motion detectors track features
D) Binocular motion detectors respond to first-order motion

Question 31

What is a spatial contrast sensitivity function, and how is its shape to be explained?

Question 32

Does the visual system perform a Fourier analysis of spatial patterns?

Question 33

How are edges located in human vision?

Question 34

How can the apparent motion of stationary stimuli be explained?

Question 35

What governs whether we see motion transparency in two superimposed patterns moving in opposite directions?