Fig. 1. Mean changes in components of velocity as a function of the relative x or y coordinates of partner fish.

(A to D) Mean change in speed over time (the mean of $\frac{\mathrm{\Delta }\mathit{s}}{\mathrm{\Delta }\mathit{t}}(\mathit{t})$) (A and B) and mean change in angle of motion over time (the mean of $\frac{\mathrm{\Delta }\mathrm{\theta }}{\mathrm{\Delta }\mathit{t}}(\mathit{t})$) (C and D) of focal fish (located at the origin, moving parallel to the positive x axis) as a function of the relative x coordinates (A and C) or y coordinates (B and D) of all other partner fish. Curves corresponding to control trials are plotted in black, curves corresponding to food treatments are plotted in green, and curves corresponding to alarm cue treatments are plotted in red. Data before application of a cue are plotted as a dashed line; post-cue data are plotted as solid lines. Dotted lines are plotted one standard error above and below each curve. Note that in (B) and (D), the motion of focal fish is out of and perpendicular to the page, toward the reader. The calculations used to generate these plots are detailed in sections S1.2 and S1.5.