Developmental trends in the processing of multidimensional stimuli.

The ability to process variations in two dimensions of a visual stimulus as efficiently as variations in one dimension was examined in a choice--reaction-time paradigm. Kindergarten children (N = 23), second graders (N = 37), fourth graders (N = 36), and college students (N = 29) were asked to determine which of three simultaneously presented geometric stimuli was different from the other two. The number of dimensions on which the different stimulus was unlike the other two was varied. Sets of trials were also either homogeneous or heterogeneous with respect to the type of dimensional variation presented in the set. The results indicated a developmental change, which is essentially complete by ten years of age, from serial to parallel processing of dimensions.