Abstract
In redundancy making (RM), the number of perceived items in repeating patterns is lower than the presented number. For example, observers frequently reported 2 Ts when presented with 3 identical Ts in their periphery. Here, we investigated whether RM occurred with highly complex stimuli: human faces. In Experiment 1, three to six identical upright or upside-down faces (3 sizes: 0.74° * 1.1°, 0.94° * 1.39°, 1.13° * 1.68°) were presented at 10° eccentricity, randomly to the left or right of fixation. The edge-to-edge spacing between faces was varied from 0° to 1.47° (prior experiments ensured that visual resolution was sufficient to resolve neighboring faces up to the largest eccentricity of 15°). Participants were asked to indicate the number of faces (1-9) and their orientation (upright or upside-down). In Experiment 2, identical upright faces, black outlines of the faces (ovals), and uniform ovals (uniformly colored with the average face color) were presented (in separate blocks). Participants indicated the number of items. There was strong RM in Experiment 1: the reported number of faces was lower than the actual number of faces, even for as few as three faces. Importantly, RM occurred for both upright and upside-down faces also when participants were able to correctly indicate the orientation of the faces (upside vs. upside-down; above 89% correct) with all face sizes (4 of 5 observers). In Experiment 2, however, strong RM occurred only with outlines. With faces and uniform ovals, RM was mainly observed with larger numbers of items. Our results showed that RM occurred with highly complex stimuli: Presenting face trios frequently resulted in reporting duos. We discuss the role of attentional allocation in RM of faces, and how stimulus complexity may modulate RM. We suggest that RM is a key mechanism to compress redundant visual information.