Lecture 6

Question 1

3 reasons why we need eye movement

Answer 1

we need eye movement because

1. the spatial resolution drops with increasing eccentricity
2. best spatial resolution at fovea
3. processing colour mainly at fovea

Question 2

how many saccades do we make per second/day?

Answer 2

per second: 3-4

per day: 230 000

Question 3

if we make so much eye movements, why is the world still stable?

Answer 3

during the saccades we cannot see

Question 4

what is the difference between overt and covert attention?

Answer 4

overt attention: attention with eye movement

covert attention: attention without eye movement

Question 5

what did Yarbus find in 1967?

Answer 5

Yarbus (1967)

> eye movements are depending on top-down knowledge (in this case, task instructions)

> this reflects enogenous (goal-driven) attention

Question 6

what is exogenous attention

> with respect to eye movement?

Answer 6

exogenous: stimulus driven attention

> responsible for involuntary eye movements

Question 7

how does goal-driven and stimulus- driven attention act when searching for a target under distractors?

Answer 7

> large effects of saliency for fast eye movement

> no effect of saliency on slow eye movement

> goal driven and stimulus driven selection act independently in different time windows

Question 8

what relationship did daniel kahneman find with respect to pupil size and task difficulty?

Answer 8

pupil size increases in proportion to the difficulty of the task being performed

Question 9

3 key facts on pupil size reactivity

Answer 9

1. pupils constrict even when you only imagine a bright stimulus
2. pupils react when you prepare eye movement to bright/dark area
3. pupil size is good predictor of awareness (binocular rivalry)