Lecture 8: Perception of motion

Question 1

motor detector

Answer 1

Reichardt in 50s - general idea is that taking two points in space at a time delay and comparing them works motion detector which can make predictions

Question 2

Apparent Motion

Answer 2

When still images are pieced together to make something looks like motion (films, phone TVs etc) - timing and spacing is very importance

Question 3

What is the other route for motion

Answer 3

Inferred (we can close our eyes and open them and still infer something about motion)

Question 4

Random dot patterns (Braddick, 1974, 1980)

Answer 4

When random dot patterns were shown that changed slightly we cant detect the motion due to it being too much for our brain to cognitively .

Question 5

under what conditions is it possible to detect the movement in the random dot patterns?

Answer 5

displacment <0.35

time intervals <100ms

Question 6

The two systems to motion:

Answer 6

Short - range process (SRP) relying on response of low levels motion detectors
Long range process (LRP) cognitive processing

Question 7

Direction selective cells:

Answer 7

Cells that are sensitive to certain directions: found in the V1 and other areas talked about in future lectures

Question 8

Discuss Snowden et al 1992

Answer 8

Experiment showing how certain cells fired more for certain directions - have two clear concepts: apparent motion and the delay and compare model (makes up directionally selective cells).

Question 9

Makami et al (1986)

Answer 9

located cells and their direction - they manipulated the time of the stimulus and how far apart they were

Question 10

Motion after effect

Answer 10

prolonged motion of one sort often induces after effect of the oppotiste motion

Question 11

motion after effect explained:

Answer 11

two detectors w opposite direction preferences, when one gets adapted to one motion and the motion is removed, this tends to go below the normal rate as it has exhausted leading to perceived opposite motion

Question 12

what reserach shows this motion after effect?

Answer 12

Barlow and Hill (1963)

Question 13

What part of motions are motion neruones also responsive to?

Answer 13

Speed, but also contrast

Question 14

How is motion, speed and contrast related and what study?

Answer 14

Things appear to be moving slower when contrast is reduced (mistake less firing t slower speed) - Thompson 1982, Snow den et al 1998