PSYC20007 Lecture Notes - Lecture 8: Stroop Effect, Simple Features, Attentional Blink
10 May 2018
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Lecture 8
- The psychological function of spatial attention: to assign limited-capacity processing resources
to relevant stimuli in environment; must locate stimuli among distractors and process (identify)
them
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- Visual search: Laboratory analogue of cheetahs-in-the-savannah
- Measure mean RT as a function of display size
- Some search tasks are easy, some search tasks are hard
- Pop-out effets: soe seah tagets see to pop out fo the akgoud; othes euie
attention
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- Pop-out effects with simple features: unique colours and unique orientations both pop out
- Parallel Search for Feature Targets:
- → Mean RT doesn’t increase with display size
- → Compare contents of each display location with mental representation of target at the
same time - parallel search
- → Make a decision that every one of the stimuli in the display is or is not the target
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find more resources at oneclass.com
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- Conjunction Targets Do Not Pop Out
- ⇒ Target defined by combination of colour and orientation
- ⇒ RT increases linearly with display size
- ⇒ Slope twice as steep for target absent as target present trials
- Evidence For Serial Search:
- Seem to need to focus attention on target to detect it - focus attention on each item in turn
- Constant scanning rate predicts linear RT/display size function
- Self-Terminating Serial Search:
- Stop when target is found
- On average, search half the display on target-present trials, all of the display on target-absent
trials
- Constant scanning predicts 2:1 slope ratio
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- Pop-Out Effects With Letter Stimuli:
- ◈ Pop out when targets can be identified by single features (straight lines among curves or vice
versa)
- ◈ No pop out he tagets a’t e idetified y a sigle featue staight lies aog staight
lines or curves among curves)
find more resources at oneclass.com
find more resources at oneclass.com
- Feature Integration Theory (Treisman & Gelade, 1980)
- Role of attention is to bind features into perceptual compounds
- Each feature (lines, colours, etc) registered in its own feature map
- Without attention features are free-floating, may lead to illusory conjunctions
[incorrectly conjoining the red feature to vertical feature]
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find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
The psychological function of spatial attention: to assign limited-capacity processing resources to relevant stimuli in environment; must locate stimuli among distractors and process (identify) them. Measure mean rt as a function of display size. Some search tasks are easy, some search tasks are hard. Pop-out effe(cid:272)ts: so(cid:373)e sea(cid:396)(cid:272)h ta(cid:396)gets see(cid:373) to (cid:862)pop out(cid:863) f(cid:396)o(cid:373) the (cid:271)a(cid:272)kg(cid:396)ou(cid:374)d; othe(cid:396)s (cid:396)e(cid:395)ui(cid:396)e attention. Pop-out effects with simple features: unique colours and unique orientations both pop out. Mean rt doesn"t increase with display size. Compare contents of each display location with mental representation of target at the same time - parallel search. Make a decision that every one of the stimuli in the display is or is not the target. Target defined by combination of colour and orientation. Rt increases linearly with display size. Slope twice as steep for target absent as target present trials. Seem to need to focus attention on target to detect it - focus attention on each item in turn.
