A Developmental Study of Shape Integration Over Space and Time

Three experiments with observers aged 6 to 21 years examined the integration of shape information over successive glances. In Experiments 1 and 2, observers classified line drawings subtending 1°-16° visual angle as possible or impossible objects. Response times and errors increased as a function of figure size for all age groups. Furthermore, the decline in performance with figure size was greater for children than for adults, suggesting improvements with age in shape integration. In Experiment 2, observers also performed a classification task based on only one of the informative regions in each figure. This task served as a control for baseline age differences in response speed and accuracy. A subtractive analysis comparing performance in the two tasks suggested that the ability to encode shape information from a single region of the figures did not change with age. In Experiment 3, relevant aspects of line drawings were separated in time rather than in space. A simultaneous condition, in which an intact figure was presented, was compared with sequential conditions in which blank intervals of 0 s - 3 s separated two views of different parts of the figure. All observers classified the figures most quickly and accurately in the simultaneous condition, and children were more affected by longer delays between views than adults. These results point to age-related improvements in the sequential integration of shape information, both when integration occurs through successive glimpses over space and when information is separated only in time.