Visual searching different from other visual behaviour, study finds
When we search for objects in a given scene, our focus tends to shift away from objects that we have already viewed towards objects or areas that are new to us. The response, known as 'inhibition of return' (IOR), allows us to ignore those items that are unimportant in our search and concentrate on those items that are. Psychologists in the Netherlands and the US have found that IOR is unlikely to apply to our visual behaviour when we are not searching for a specific target. The findings are published in the journal Psychological Science. Through a series of tests conducted by tracking the eye movements of volunteers, Stefan Van der Stigchel of Utrecht University in the Netherlands and colleagues in the US discovered that IOR takes place when we perform tasks related to visual search but not necessarily during other visual tasks. The 48 subjects were separated into 4 groups. Each group was provided with a different set of instructions for viewing the test scenes: search for a target; memorise each scene; rate how pleasing each scene is to the eye; and view the scene in whichever way is preferred (voluntary, or free-view). As each group engaged with the various scenes (68 computer-generated scenes depicting common environments), information was recorded at each moment of the specific location on which the eyes were fixed. During the test, a target would appear in the scene, either in a location they had already been exposed to or in a new one. The volunteers in the group who were asked to search for a target were slower to divert their eyes to locations they had already viewed than they were to new places, which is consistent with IOR response and with findings of previous studies. However, the reverse was true for the volunteers in the other three groups; results showed the opposite in eye-movement pattern. These volunteers were quicker to look at objects in locations on which they had already fixated than they were to look at new ones. According to the researchers, this is the first time that such an effect, called 'facilitation of return', has been reported. 'Although there is ample evidence that IOR influences search behaviour, IOR is often discussed as though it is a general characteristic of attention,' the study reads. 'That is, attention is thought to be slower to return to recently inspected locations regardless of the task set, despite the fact that there has been little systematic investigation of this issue.' The results demonstrate that IOR is a strategy specific to visual search tasks and not a general characteristic of visual attention.
Countries
Netherlands, United States