People's attention does not return time and again to the objects they have already seen while searching for something, but they tend to shift their eyes to previously fixated locations when performing other visual tasks, according to a study.
Psychologists Michael D. Dodd from the University of Nebraska - Lincoln, Stefan Van der Stigchel of Utrecht University, and Andrew Hollingworth from the University of Iowa tracked eye movements of volunteers as they viewed various scenes, and recorded the location where the eyes were focused at each moment.
The volunteers were divided into four groups, with each group receiving different instructions for scene viewing.
They were told to search the scenes for a specific target, memorize each scene, rate how pleasant the scenes were, or free-view the scenes.
A target appeared in the scene during viewing, and the participants shifted their eyes as quickly as possible to the target. The target either appeared in an old location or a new location.
The researchers observed that the participants' attention was less likely to return to objects they had already viewed during visual search tasks, but not during other visual tasks.
They said that the volunteers in the search group were slower to shift their eyes to previously fixated locations than to new locations.
However, the subjects in the other three groups exhibited the opposite pattern of eye movements: they were faster to shift their eyes to previously fixated locations than to new locations.
Based on their observations, the researchers came to the conclusion that the "facilitation of return" effect might be "the default setting of the visual system, with inhibition of return representing an exception implemented during visual search."
The study has been reported in the journal Psychological Science.