Texture segmentation and 'pop-out' in infants and children: the effect of test field size

The ability of infants and children to segment textures based on differences in line orientation and blob size was investigated, using a forced-choice preferential looking method. In the first experiment, a stimulus pair (a homogeneous texture and a texture containing either a group of sixteen elements or a single element of an orthogonal orientation or a larger blob size) was presented on two separate test fields. Preference for the figure defined by differences in blob size was seen already in 2-month-old infants. In contrast, preference for a figure defined by differences in orientation emerged at 9-12 months of age and became adult-like around school age (see also Sireteanu and Rieth, Behavioural Brain Res., 49, 133-139, 1992). Preference for the single discrepant element was always lower than preference for the discrepant group. In the second experiment, segmentation of oriented textures presented on a single, rather than two separate surfaces was tested. A significant preference for the embedded discrepant group, but not for the single discrepant element, was seen already at 3 months of age. These results show that infants as young as 3 months of age are able to detect a boundary defined by differences in line orientation (see also Atkinson and Braddick, Behavioural Brain Res., 49, 123-131, 1992). However, this ability does not appear to lead to the 'pop-out' phenomenon, as seen in adult observers, until much later.