Visual search is a type of
perceptual
Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system, ...
task requiring
attention
Attention is the behavioral and cognitive process of selectively concentrating on a discrete aspect of information, whether considered subjective or objective, while ignoring other perceivable information. William James (1890) wrote that "Att ...
that typically involves an active scan of the visual environment for a particular object or feature (the target) among other objects or features (the distractors). Visual search can take place with or without eye movements. The ability to consciously locate an object or target amongst a complex array of stimuli has been extensively studied over the past 40 years. Practical examples of using visual search can be seen in everyday life, such as when one is picking out a product on a supermarket shelf, when animals are searching for food among piles of leaves, when trying to find a friend in a large crowd of people, or simply when playing visual search games such as ''
Where's Wally?
''Where's Wally?'' (called ''Where's Waldo?'' in North America) is a British series of children's puzzle books created by English illustrator Martin Handford. The books consist of a series of detailed double-page spread illustrations depicti ...
''
Much previous literature on visual search used reaction time in order to measure the time it takes to detect the target amongst its distractors. An example of this could be a green square (the target) amongst a set of red circles (the distractors). However, reaction time measurements do not always distinguish between the role of attention and other factors: a long reaction time might be the result of difficulty directing attention to the target, or slowed decision-making processes or slowed motor responses after attention is already directed to the target and the target has already been detected. Many visual search paradigms have therefore used eye movement as a means to measure the degree of attention given to stimuli.
However, eyes can move independently of attention, and therefore eye movement measures do not completely capture the role of attention.
Search types
Feature search
250px, feature based search task
Feature search (also known as "disjunctive" or "efficient" search)
is a visual search process that focuses on identifying a previously requested target amongst distractors that differ from the target by a unique visual feature such as color, shape, orientation, or size.
An example of a feature search task is asking a participant to identify a white square (target) surrounded by black squares (distractors).
In this type of visual search, the distractors are characterized by the same visual features.
The efficiency of feature search in regards to
