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What is Visual Search? One of the most widely used methods of studying visual attention
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Goals for Today’s ClassTo introduce “attention” as a
psychological phenomenonTo contrast serial and parallel
processingTo demonstrate how experimentation
can be used to understand mental processes
What is Visual Search?• One of the most widely used
methods of studying visual attention
Basic Method of Visual Search
Find target hidden among distractors in multi-element display
• 2 Processes to Visual Search• Parallel vs Serial Processing • Parallel Processing = Preattentive
Processing• Serial Process = Attentive
Processing
Preattentive ProcessesProcesses that occur automaticallyProcesses that apply to all objects in
our visual fieldPreattentive processes allow us to
take in everything around us
Feature Search• Is there a red T in
the display?• Target defined by
a single feature• No attention
required• Target should
“pop out”
Attentive Processes
Attentive processes require control on the part of the perceiver
Through attentive processing, we examine one component of the visual field at a time
Conjunction Search• Is there a red T in the
display?• Target is now defined
by its shape and color• This involves binding
features and should demand attention
• Need to attend to each item until target is found
Conjunction Search
When there is no single feature that sets the target apart from all of the distracters
Targets are generally more difficult to find in conjunction searches than in feature searches
Difficulty increases with the number of distracters in the display
Questions for Today’s Lab:
Which type of search will take longer: Feature search(using parallel processes) or Conjunction search (using serial processing)?
Design:• 3 IVs: • task (feature or conjunction search)• display size (4, 8, or 12 items)• trial type (target present or target
absent)• DV: RT
Response Time Data
Conclusions:As the number of elements in the display
increases, so does the response timeResponse time is significantly greater
during conjunction searches - cannot process everything at once, must process one thing at a time (serial processing)
response time is higher when target is absent