Fig. 4.

Reference repulsion for perception of a crowd of walkers. Note that for both panels, crowd heading is depicted using a single walker. (a) Observers were most sensitive to the headings of approaching crowds. Response variability decreased for crowd headings near the category boundary, as shown by a good fit from a Gaussian function to the average of all observers (solid black). (b) Reference repulsion was very strong for the perception of a crowd. Error bars represent ±1 SEM.