Visual search Flashcards
Serial search
~ look for one target at a time before moving to the next one
~ the more distracting objects (set size), the harder it is
Parallel search
~ used when searching for multiple targets
~ no. of distractors doesn’t not mean a harder search
Feature search
~ when the target is defined by a certain features it seems to ‘pop-out’
~ set size makes no difference
How are stimuli processed for their features?
In parallel
Treisman suggestion on feature searches.
1986
~ ‘feature maps’ analyse the visual field and extracts out primitive features in parallel
Conjunction searches
when the target is has combination of attributes, a SLOW SERIAL search is needed
Feature integration theory
Treisman (1988; 1992)
~ features are “registered early, automatically, and in parallel”
~ “while objects are identified separately” and at a later stage in processing
When is attention needed in the feature integration theory?
for conjunctions of features in order to integrates the features into the whole item
How does set size affect feature searches?
It doesn’t
How does set size affect conjunction searches?
as set size increases, so does reaction time
Illusory conjunctions (date/name)
Prinzmetal at al. (1995)
~ accurate feature binding needs slow serial attention
~ when that is not allowed features get mixed up between stimuli
e.g. black X, green T and red O becomes green X
Guided search
When we focus on certain features of the object and then serially search through all the items that match that description in order to find the target
Issues for the feature integration theory (3)
~ guided serial search - parallel processes differentially activate diff feature maps
~ serial searches can very in efficiency (Wolfe)
~ Duncan + Humphrey’s study (1989)
