Perceptual learning: 12-month-olds' discrimination of monkey faces.

Six-month-olds reliably discriminate different monkey and human faces whereas 9-month-olds only discriminate different human faces. It is often falsely assumed that perceptual narrowing reflects a permanent change in perceptual abilities. In 3 experiments, ninety-six 12-month-olds' discrimination of unfamiliar monkey faces was examined. Following 20 s of familiarization, and two 5-s visual-paired comparison test trials, 12-month-olds failed to show discrimination. However, following 40 s of familiarization and two 10-s test trials, 12-month-olds showed reliable discrimination of novel monkey faces. A final experiment was performed demonstrating 12-month-olds' discrimination of the monkey face was due to the increased familiarization rather than increased time of visual comparison. Results are discussed in the context of perceptual narrowing, in particular the flexible nature of perceptual narrowing.