Detection of Hidden Figures by Rhesus Monkeys 1,2

Abstract

Three rhesus monkeys discriminated between two forms and were then tested for identification of the forms when they were hidden by adding lines (Exp. 1). Ss were retested twice after discriminating between the forms with lines around them (Exp. 2) and, again, after discriminating between the forms with lines touching their sides (Exp. 3). Contrary to data from humans, embedded forms were not more difficult to identify than were masked forms. Ss consistently performed worse when lines touched the sides of the forms than they did when lines touched other portions of the forms. These findings suggest that over the three experiments, Ss were learning to attend to some feature of the sides of the forms rather than to their configurations.