Attention & Scene Perception

Question 1

What is attention?

Answer 1

• Ability to preferentially process some parts of a stimulus (more clear than others)
  
  • At the expense of processing other parts of the stimulus

Question 2

Why is attention needed?

Answer 2

• Perceptual system has a limited capacity
  
  • Can’t process everything in visual scene simultaneously
  • Helps in not being overwhelmed

Question 3

What is the difference between overt and covert attention?

Answer 3

• Overt → Looking directly at an object
• Covert → Looking at one object but attending to another

Question 4

What are saccades?

Answer 4

• Ballistic eye movements between fixations
• Jump from point to point instead of smoothly
  
  • Generally always looking at object that you are attending to → Can tell where someone is attending by tracking eye movements

Question 5

What are fixations?

Answer 5

• Rests inbetween visual jumps (saccades)
• Eyes stay looking directly at one part of the scene

Question 6

What directs attention?

Answer 6

• Initial involuntary
  
  • Attentional capture → First presented, fixations captured by salient parts of scene
• Subsequent voluntary
  
  • Directing to goals

Question 7

Name 4 types of contrast

Attentional Capture (Salience)

Answer 7

• Colour/ luminance
• Size
• Orientation
• Motion/ flicker

Question 8

What are fixations determined by?

Answer 8

• Cognitive Factors
  
  • Goals
  • Expectations
    
    • If object is unexpected → Fixate on it for longer + More often

Question 9

What are the effects of attention?

Answer 9

• Change speed of response
• Influence appearance
• Influence physiological responding

Question 10

What is the binding problem?

Answer 10

• Issue of how an object’s individual features are combined to create a coherent percept
  
  • Different aspects of a stimulus are processed independently (separate brain areas)
• More difficult with multiple objects

Question 11

What is the Feature Integration Theory (FIT)?

Answer 11

• Suggests that binding problem is solved by attending to only one location at a time
• Only features associated with location are process → Only they are bound together
  
  • Avoids binding features from different objects

Question 12

What are illusory conjunctions

Answer 12

• If attention is inhibited, features from different objects will be incorrectly bound together
  
  • Prediction of FIT

Question 13

Describe the case of RM

Answer 13

• Parietal lobe damage → Balint’s syndrome
  
  • Multiple objects present = Difficulty focusing attention on a single object
• Prone to experiencing illusory conjunctions because he cannot focus attention on a single object
  
  • Shown two letters with different colours
  • Reported the wrong letter colour combinations on 23% of the trials → Even when allowed to view for 10s

Question 14

What is a visual search?

Answer 14

• Looking for a target requires binding if target has same features as distractors

Question 15

What is a conjunction search?

Answer 15

• Target different from distractors only by its particular conjunction of features
• Attention needs to be applied to each object in turn (FIT) to find target
• Therefore are slow

Question 16

What is a feature search?

Answer 16

• Without solving binding problem
• Target has feature that distractor doesn’t have
• Because binding isn’t required, attention does not need to be applied to each item in turn (FIT)
• Searches predicted to be fast

Question 17

What is change blindness?

Answer 17

• Things not attended to are not remembered
• Change needs to be missed when attention is not drawn to the location of the change
  
  • But change must then be obvious when attention is drawn to the change
  • Can’t make small changes
  • Need to be large but also missed

Question 18

Why doesn’t change blindness occur all the time?

Answer 18

• Changes usually generate motion transients that draw attention to the location change
  
  • Easy to spot change