Figure 1.

Computer generated visual stimuli. Black disks (7 cm) travelling at a velocity of 300 cm/sec were presented to the locust along eight different trajectories, each against three different visual backgrounds. Three types of object motion were presented: looming, transitions to looming, and transitions away from looming. (A) L_0 was designated as a frontal loom towards the animal. A transition from this trajectory at a 45° angle occurred at 60 cm away from the animal (0_45). (B) Disk approaching orthogonal to the long axis of the locust's body 50 cm anterior to the eyes, that transitioned toward (H_T) or away (H_A) from looming at an angle of 45° starting 75 cm away from the locust. (C) Disk travelling along a looming trajectory at a 45° angle to the locust's eye (L_45). The disk also transitioned 43 cm from the eye 90° orthogonal to the original trajectory (L_45_A). (D) Disk motion started parallel to the long axis of the locust's body in the anterior field of view, offset from locust's long axis by 30 cm, approached until parallel with the middle of the locust's eye (90°) and transitioned toward (0_90_T) or away from (0_90_A) the locust. (E) Visual representations of the three stimulus backgrounds used: Simple (S), Scattered (SC), or Flow field (FF). Modified from Silva et al. (2015). Arrows in A–D represent the relative direction of object motion. Arrows next to diagrams in E indicate that the objects moved in all directions (scattered) or the vertical bars expanded outward from the center (flow field). See Materials and Methods for additional descriptions.