A DEVELOPMENTAL-STUDY OF VISUAL-ATTENTION - ISSUES OF FILTERING EFFICIENCY AND FOCUS

A forced-choice reaction time (RT) task was used to assess development al changes in filtering and the concomitant ability to narrow the focu s of the attentional lens. Participants included 20 children in each o f four age groups (4, 5, 7, and 9 years), as well as 20 adults between the ages of 21 and 29 years. Conditions varied with regard to the pre sence or absence of distracters and their proximity to a target stimul us, and the presence or absence of a visual window within which the ta rget stimulus was presented. Age-related differences in the ability to filter task-irrelevant stimuli were found. The performance of 4-year- old children was adversely affected with the presence of distracters l ocated at both 5.7 degrees and 0.95 degrees of visual angle from targe t stimuli, whereas that of children aged 5, 7, and 9 was negatively af fected only with distracters 0.95 degrees of visual angle from the tar get. Adults' performance was not adversely affected by the presence of distracters. Developmental differences in focusing attention were fur ther highlighted by the finding that the presence of a visual window c ue was only associated with faster RTs among 4-year-old children. Thes e results are discussed in terms of the zoom-lens metaphor of visual a ttention, and the development of the ability to vary the size of an at tentive zoom-lens in response to task requirements.