A developmental study of filtering in visual attention.

Children aged 4, 5, and 7 years and adults aged 20 years performed a speeded classification task designed to isolate several sources of interference in visual selective attention. On each trial, observers responded to 1 of 4 targets which were mapped to 2 responses. On some trials the targets were also flanked by distractor stimuli, which observers were asked to ignore. The interference measures examined the effects of attentional set, increases in feature number, increases in feature type, response competition, and stimulus generalization. All but 1 of the measures (stimulus generalization) produced reliable interference in the adult observers. However, only 2 of the measures (attentional set, increases in feature number) produced reliable interference in children. The implications of these findings for theories of attentional development are discussed.