Fig. 1: Behavioral protocol.

A Crows were trained on a delayed-response task whereby visual stimuli (B) cued the crow to estimate 1500, 3000, or 6000 ms. Each trial began with a “Ready” period (up to 5000 ms) in which the subject moved into position using a light barrier. Moving into position triggered a 300 ms pre-cue period and then 600 ms cue period. Colored squares and shapes served as the cues and instructed the subject on the minimum wait time required before (“Wait” period), leaving the light barrier (“Go” period). Importantly, the “Wait” and “Go” periods matched in duration to account for the increased variance in response time with longer estimates. Here, we present an example of a 1500 ms trial.