Sensitivity to spacing changes in faces and nonface objects in preschool-aged children and adults.

Sensitivity to variations in the spacing of features in faces and a class of nonface objects (i.e., frontal images of cars) was tested in 3- and 4-year-old children and adults using a delayed or simultaneous two-alternative forced choice matching-to-sample task. In the adults, detection of spacing information was robust against exemplar differences for faces but varied across exemplars for cars (Experiment 1A). The 4-year-olds performed above chance in both face and car discrimination even when differences in spacing were very small (within ±1.6 standard deviations [SDs]) and the task involved memory components (Experiment 1B), and the same was true for the 3-year-olds when tested with larger spacing changes (within ±2.5SDs) in a task that posed no memory demands (Experiment 2). An advantage in the discrimination of faces over cars was found at 4years of age, but only when spacing cues were made more readily available (within ±2.5SDs). Results demonstrate that the ability to discriminate objects based on feature spacing (i.e., sensitivity to second-order information) is present at 3years of age and becomes more pronounced for faces than cars by 4years of age.