Attention in Space and Time (Visual Search) PDF

Attention V. Attention in Space and Time (Visual Search and the Effects of Distractors) Goldstein, pp. 100-106, 110-111, 119-121 Styles, ch. 5 “Visual Attention” pp. 86-93 Wolfe (2021) Guided Search 6.0: An updated model of visual search ...

Attention V. Attention in Space and Time (Visual Search and the Effects of Distractors) Goldstein, pp. 100-106, 110-111, 119-121 Styles, ch. 5 “Visual Attention” pp. 86-93 Wolfe (2021) Guided Search 6.0: An updated model of visual search  Learning Objectives  Explain the visual search task and describe the features of real-world attention it investigates  Describe the phenomenon of "pop-out" and explain what it means about process of search  Describe what is meant by parallel and serial search and characterise the conditions under which they are found  Explain how Treisman's Feature Integration Theory accounts for parallel and serial search  Identify a weakness of Feature Integration Theory and explain how it is fixed by Wolfe's Guided Search Theory  Explain what the Stroop effect tells us about the limitations of focused attention  Explain what is meant by "automaticity" and describe the conditions under which it develops  Describe the attentional blink and explain its significance for our understanding of attentional processes.  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  Visual Search  Laboratory analogue of cheetahs-in-the-savannah Control complexity of search by varying the number of items  Visual Search  Laboratory analogue of cheetahs-in-the-savannah Measure mean response time (RT) as a function of display size Early experiments used stimuli like letters because they were easy to program Easy to quantify similarity as number of features in common  Visual Search  Some search tasks are easy…  Visual Search  Some search tasks are hard …  Pop-Out Effects  Some search targets seem to “pop out” from the background; others require attention  Pop-Out Effects in the Laboratory  Pop-out targets show little or no change in search times (RT) with set size  Non pop-out targets show large changes in search times with set size  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  Yes (target present) and no (target absent) trials take the same time  Compare contents of each display location with mental representation of target at the same time – reject distractors and locate target  Parallel search  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 rate predicts 2:1 slope ratio 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  Feature Integration Theory  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  Lots of experiments show this…. Problems With FIT  Pop out sometimes depends on complex object properties, not just simple features (Enns & Rensink, 1990)  High-level, not low-level properties predict pop out.  Inconsistent with idea that pop out only occurs at level of simple features There are Other Patterns of Search RTs  Many tasks show intermediate pattern, no clear evidence of either serial or parallel search  Wolfe (1998) What Can 1 Million Trials Tell Us About Visual Search?  Search slopes from 2,500 experimental sessions (!)  Slopes are very variable  No evidence of dichotomous population of search slopes; parallel and serial functions look like ends of continuum  Wolfe: better described as inefficient or efficient search  Guided Search Theory (Wolfe, Cave, Franzel, 1989)  Two-stage theory  Initial parallel stage provides a candidate list of possible targets  Second serial stage checks candidate list for targets  Search efficiency depends on 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  Predicts a range of search slopes  cf. Two-stage auditory theories  Guided Search 2.0 (Wolfe, 1994)  In Guided Search (1.0) search controlled by similarity between targets and distractors  Guided Search 2.0 search controlled by a priority map – depends on the salience of stimuli (bright, distinctive, unique….)  Guided Search 6.0 (!) (Wolfe, 2021)  Later versions of Guided Search investigated rules and mechanisms of attention guidance  Scene Guidance: real world images rather than isolated elements – “meaning maps,” not just salience (toothbrush in bathroom scene, etc.)  Attention VI. Automaticity and Failures of Focused Attention Goldstein, pp. 93-94, pp. 101-102 Braisby & Gellatly, 50-54  Failures of Focused Attention  Visual search looks at costs of divided (distributed) attention: performance decline with increasing display size is evidence of capacity limitations  Some situations where there is a benefit not to divide attention: avoid processing distractor stimuli  Limitations of focused attention and involuntary processing of irrelevant stimuli  The Stroop Effect (Stroop, 1935) The First Demonstration of a Focused Attention Failure  Name the colour of the ink in which the word is written; measure RT  Fast with compatible (top), intermediate with neutral (middle), slow with incompatible (bottom)  Why Does Focused Attention Fail? Involuntary (Automatic) Processing of Irrelevant Attributes  Parallel processing of colour naming and word reading  Word reading is fast and involuntary – You can’t not read the word!  Word name available before colour name, creates output interference  Asymmetrical: no interference of ink colour on word naming John Ridley Stroop (1897-1973)  From Stroop’s bio: “From his college days on, he preached every Sunday, often taking a train out into the country and being paid with a chicken or a bag of potatoes, if at all.”  Published seven books of religious studies  Stroop's children were all colour blind...!  Automaticity  Stroop effect: – Word reading: “fast and automatic” – Colour naming: “slow and controlled” – What makes a process automatic? Learned S-R associations – Criteria for automaticity: Fast, parallel, effortless, doesn't require capacity – Automaticity basis for skill acquisition (reading, driving, playing a musical instrument, etc.) – Allport, Antonis, Reynolds (1972) – Skilled pianists could perform dichotic- listening/shadowing task while sight-reading music Controlled and Automatic Processing Shiffrin & Schneider (1977)  Search for digit targets in arrays of distractor letters in rapid sequences (or vice versa)  Vary size of target (memory) set: 1-4 items  Vary size of stimulus displays: 1-4 items  Consistent mapping (CM): target and distractor sets were distinct  Varied mapping (VM): targets on some trials were distractors on others Controlled and Automatic Processing Shiffrin & Schneider (1977)  Performance under CM became automatic with practice (>90%)  Became independent of memory set and display size  Subjectively effortless, spontaneous pop-out of targets from text  Never became automatic under VM  Requires consistency of target set membership  Consistent with capacity-free, effortless encoding account  Consistent with structure practice approach to skill development Failures of Focused Attention in Spatial Attention The Eriksen Flanker Task  Is the central character a “>” (respond right) or a “