Developmental trajectories of form perception: A story of attention.

The developmental trajectories of selective and divided attention were examined in relation to the processing of hierarchically integrated stimuli. The participants included children in 4 age groups (6, 8, 10, and 12 years) and a group of young adults (24 years) who completed 2 computer-based attention tasks. In the selective attention task, the participants were instructed to attend to only 1 level of analysis and ignore the other. In the divided attention task, participants were told that the target could appear at either level, and the probability that a target would appear at either the global or local level was manipulated. For both of the tasks, distinct and qualitative developmental shifts were evident both between 6 and 8 years of age and between 8 and 10 years of age. Attention to the global form developed prior to, and may have been a prerequisite of, attention to the local form. These gains in attentional control occurred in terms of selective attention, sensitivity to the probability of bias, and relative efficiency in processing global and local targets. The clear developmental trajectory is consistent with the emergent role of voluntary attention in the processing of these types of stimuli.