Randomized starting positions force subjects to use motion direction rather than location

Evidence

Within a trial the reference stimuli (repetition period 1300 ms) had the same direction, while the test was a single stimulus presented with opposite motion direction. Each stimulus started at a random position between ‑42° and + 42° in azimuth. This prevented the owls from using location per se rather than motion direction to solve the task. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3187