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 non-face 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 adults, the detection of spacing information was robust against exemplar differences for faces, but varied across exemplars for cars (Exp. 1A). Four-year-olds performed above chance in both face and car discrimination even when differences in spacing were very small (within ±1.6 SD) and the task involved memory components (Exp. 1B), and the same was true for 3-year-olds when tested with larger spacing changes (within ±2.5 SD) in a task which posed no memory demands (Exp. 2). An advantage in the discrimination of faces over cars was found at 4 years of age, but only when spacing cues were made more readily available (within ±2.5 SD). Results demonstrate that the ability to discriminate objects based on feature spacing –i.e., sensitivity to second-order information– is present at 3 years, and becomes more pronounced for faces than cars by the age of 4.