Figure 1. The examples of stimuli used in Experiment 1.

The letter of each label indicates the Pair-condition (single or paired), and the number in each label indicates the Number-of-eyes-condition (1, 4, 16, or 64). The 256 × 256 pixels of the real eye image were created using the 64 × 64 pixels of one eye in the 1- and 16-eye-condition. The 4-eye-condition used the 128 × 128 pixels of the real eye image. The 64-eye condition used the 512 × 512 pixels of the real eye image.