Fig 1.

A. Stimulus examples shown in Experiment 1 and 3. What is shown are upright examples on the left panel and inverted examples on the right. The different stimulus categories are shown in each row, with human faces in the first row, chimpanzee behinds in the second, and human feet in the third. The correct response in each row, starting at the top, is left, right, and right (the same response is correct for both the upright and inverted examples). B. Chimpanzee behinds (depicted on the left), contain specific features like human faces (depicted on the right). The black lines highlight those features. C. An example of a chimpanzee participant conducting the task with desaturated images. Experiments 2 and 4 used desaturated images.