Required pecking and refraining from pecking alter judgments of time by pigeons

There is evidence that humans' perception of time is affected by the activity in which they are engaged while they are timing. The more demanding the task, the faster time appears to pass. A similar effect has been found in pigeons. Pigeons trained to discriminate between a short-duration (2-sec) and a long-duration (10-sec) stimulus were required to peck when the stimulus was one color and to refrain from pecking when it was a different color. On probe trials of intermediate durations, the bisection point (50% choice of the stimulus associated with both long and short stimuli) for trials in which the pigeons were required to peck was almost 1 sec longer than on trials in which the pigeons were required to refrain from pecking (Zentall, Friedrich, & Clement, 2006). In the present research, we replicated this effect and determined the relation between this effect and the typical bisection point that occurs when pecking is permitted but not required. Results indicated that the typical procedure results in a bisection point that is between required pecking and refraining from pecking. Furthermore, the rate of pecking when pecking is allowed but not required also falls between the rate of pecking for the required-pecking and refrain-from-pecking conditions. This result suggests that, similar to humans, pigeons underestimate the passage of time when they are active or when attention to time-related cues has to be shared with attention to satisfying the response requirement.