7 - Attention in Space & Time

Question 1

What are ‘pop out effects’?

Answer 1

• When some search targets seem to “pop out” from the background; others require attention.
• Unique colours and unique orientations both pop out, e.g. red from green distractors.

Question 2

What does parallel search for feature targets paradigms provide evidence in regards to the way we search for simple features?

Answer 2

• Mean RT doesn’t increase with display size (no. of distractors).
• No difference b/w target-absent & present trials.
• This suggest we compare contests of each display location at the same time - i.e. parallel search.
• We can search for two unique “pop-out” targets in parallel.

Question 3

What is the evidence for Serial Search offered by Conjunction Target (two features) tasks?

Answer 3

• Looking for “redness” & “verticality”
  
  • multiple types of distractors.
• RTs increase linearly with display size.
• Slow twice as steep for target-absent trials (compared to present) - 2:1 slope ratio.
• Seem to need to focus attention on each item in turn - serial search.
• Target Present fast = locate & stop search (self-terminating search).
• Target Absent slow = constant scanning (exhaustive scanning).

Question 4

What is the core claim of Feature Integration Theory (Treisman & Gelade, 1980).

Answer 4

• Role of spatial attention is to bind features into perceptual compounds
  
  • each feature registers on its own feature map.
    
    • e.g. lines, colours.
• Without spatial attention (spotlight) features are free-floating, may lead to illusory conjunctions.
  
  • You need to shine the spotlight of attention to bring feats together & to awareness.

Question 5

What evidence is offered for Feature Integration Theory when comparing Feature Search tasks and Conjunction Search tasks?

Answer 5

• Feature search results: no difference in number of distractors or target present/absent trials.
• Conjunction search results: Linear increase with the number of distractors & difference b/w target absent/present trials.

Conjunction targets require feature binding, so need focused attention –leads to serial search.

Feature targets don’t require feature binding, don’t need focused attention –leads to parallel search

Question 6

How did Enns & Rensink (1990) poke holes in Feature Integration Theory with complex object properties?

Answer 6

• Pop out is not defined by single feature.
• Pop out sometimes depends on complex object properties, not just simple features (Enns & Rensink, 1990)
• _High-leve_l, not low-level properties predict pop out.
• Inconsistent with idea that pop out only occurs at level of simple features

Question 7

Why did Wolfe suggest that viewing search as either inefficient or efficient is more accurate than serial vs parallel?

Answer 7

• Many tasks show an intermediate pattern, don’t provide clear evidence of either serial or parallel search.
  
  • e.g. negative accelerating RT increases w/ display size increase as opposed to linear functions proposed by serial search.
  • e.g. shallow increases in RT w/ display size as opposed to flat line proposed by parallel search.

Question 8

How does Wolfe’s (1989) Guided Search Theory view search?

Answer 8

• Initial parallel stage provides a candidate list of possible target
• Second serial stage checks candidate list for targets.
• Search efficiency depends on the similarity of target and distractors.
  
  • Similar targets and distractors lead to large candidate list and inefficient search
  • Dissimilar targets and distractors lead to small candidate list and efficient search
• We use preattentive processing to selective guide search of the display.

Question 10

What are the two processes behind the Stroop Effect?

Answer 10

Parallel processing of colour naming & word reading.

1. Fast & Involuntary word reading
2. Slow & Controlled colour naming

• Leads to output interference via the word name being available before the colour name.

Question 11

What are the criteria of automaticity?

Answer 11

• Fast, parallel, effortless, doesn’t require capacity
• Automaticity basis for skill acquisition (reading, driving, playing a musical instrument, etc.)

Question 12

What did Shiffrin & Schneider (1977) study of automatic processing with Consistent mapping (CM) vs Varied Mapping (VM) find? (hint: looking at if search task can become automatic).

Answer 12

Design:

• Pts presented a memory set ranging from 1-4 items.
• Then presented series of 20 frames (fast) - varied size of the stimulus display (1-4).
  
  • Condition 1 - Consistent Mapping (CM): target & distractors sets were distinct (number targets / letter distractors).
  • Condition 2: Varied Mapping (VM): targets on some trials were distractors on others, i.e. letter/number distractors

Results:

• Performance under CM became automatic with practice (>90%) - after about 1200-1500 trials - lots
• Became independent of memory set and display size
• Subjectively effortless, spontaneous pop-out of targets from text
• Never became automatic under VM.

Inference:

• Requires consistency of target set membership
• Consistent with capacity-free, effortless encoding account.

Question 13

What are the features of the Flanker Task? (compatibility effect - involuntary processing - parallel processing - an estimate of the size of the “spotlight” of attention).

Answer 13

• RT(compatible) < RT(neutral) < RT(incompatible) - compatibility effect.
• Involuntary processing of flankers even when attempting to ignore them.
• Implies some parallel processing of conjunction stimuli
• Failure of focused attention.
• Decreases with spatial separation & disappears at 1-1.5 degrees.
  
  • Provides estimate of the size of the focus of attention (“spotlight”)
  • Stimuli falling within spotlight processed automatically

Question 14

What is the attentional blink and how does the Rapid serial visual presentation (RSVP) task show it?

Answer 14

Attentional blink is the characteristic depression of performance (plummets) in identifying a second target (T2) after previously identifying T1 - i.e. attention blinks after the first target is located & recovers sometime later.

• Lasts about 700 ms (based on depressed performance of about 7 items - position of T2 after T1 )
• Is not immediate - but after some time later (Lag 1 sparing).
• Effect builds up but is long lasting

RSVP Task

• 100 ms exposure per item; each item masked by the following item.
• Two targets: report the white letter, detect whether there was an “X” present.

Question 15

Describe why it might be a bottleneck at decision making, as opposed attention? (hint: Single-Channel Theory, Welford 1959)

Answer 15

• We’re good at monitoring for relevant (target) stimuli, rejecting irrelevant stimuli preattentatively if they are not perceptually confusable - parallel & serial search tasks.
• Forming representations of relevant stimuli and making decisions about them makes us insensitive to new stimuli for 500-1000 ms (double-target deficit, AB) - attentional blink.
• Single-channel theory (Welford, 1959) –can only make one decision at a time.
• Therefore bottleneck is likely at the decision making level of cognition.