A number of students were interested in studies of feature detection in people and tamarins, and the tamarin work had led us to focusing on perceptual uniqueness shown by people with autism that seemed similar to trends shown by the tamarins. Specifically, tamarins did not automatically prefer to judge objects by global shape, rather they seemed to process local detail and global shape equivalently. We thought perhaps they looked at faces differently than humans as well, and at the time, many labs were presenting inverted faces to people and different species of monkeys to see if primates processed faces more wholistically, as did humans. Specifically, humans do not readily and quickly identify the identity of inverted or upside-down presentations of human faces, chiefly because the presentation scrambles the relative location of eyes, nose, and mouth and we rely on the placement of these components relative to each other to identify a face.

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To this end, Janice Hassett and Cara Sylvester (2003) worked together to test tamarin monkeys on differently oriented human faces, tamarin faces, chimpanzee faces, and a variety of common lab objects. Below is an example of the stimuli we used in a look rate study.