The role of keypecking during filled intervals on the judgment of time for empty and filled intervals by pigeons

Abstract

Pigeons were trained in a within-subjects design to discriminate empty intervals (bound by two 1-sec visual markers) and filled intervals (a continuous visual signal). The intervals were signaled by different visual stimuli and they required responses to different sets of comparison stimuli. In Experiment 1, empty intervals were judged longer than filled intervals. The difference between the point of subjective equality (PSE) for the empty intervals and the PSE for filled intervals increased as the magnitude of the anchor-duration pairs increased. Although there was more pecking during filled intervals than during empty intervals, there was no significant correlation between pecking during filled intervals and the value of the PSE. In Experiment 2, empty intervals continued to be judged longer than filled intervals, even when pigeons were required to refrain from pecking during filled intervals. Keypecking per se does not appear to play an important role in the empty-filled timing difference.

Rats' choices with token stimuli in concurrent variable‐interval schedules

“…This difference between the two species, though not large, shows that the pigeons' choice percentages were almost entirely controlled by the number of visible token lights, whereas both the visible token lights and the passage of time served as discriminative stimuli for the rats. This difference between species is consistent with studies using timing procedures, where visual stimuli have been found to exert greater control over the timing of intervals for pigeons than for rats (e.g., Cheng & Roberts, 1989;Roberts, 1981;Santi, Adams, & Bassett, 2010). Mazur and Biondi (2013) showed that the pigeons' choice percentages in all the conditions of their experiments could be described reasonably well by a simple mathematical model based on two principles-matching and the hyperbolic decay of reinforcer value.…”

Delayed matching-to-sample: A tool to assess memory and other cognitive processes in pigeons

“…If so, Zentall et al (2008) have shown that pigeons tend to judge intervals as shorter when they are pecking than when they are not pecking. However, Santi et al (2010) tested this hypothesis by requiring that pigeons refrain from pecking during both the filled and unfilled intervals and it did not eliminate the judgments that the filled intervals were shorter than the unfilled intervals. The distraction hypothesis was further supported by an experiment by Santi et al (2007) in which it was found that when the temporal signals were auditory rather than visual, and attention no longer needed to be shared between the filled interval and visual contextual cues, there was no longer a difference in judged duration between the filled and unfilled intervals.…”