The Perception of Empty and Filled Time Intervals by Pigeons

Abstract

Pigeons were trained in a within-subjects design to discriminate durations of a filled interval (2 s and 8 s of light) and durations of an empty interval (2 s and 8 s bound by two 500-ms light markers). Filled intervals required a response to one set of comparisons (e.g., blue vs. yellow), whereas empty intervals required a response to a different set of comparisons (e.g., red vs. green). Psychophysical testing indicated that empty intervals were judged to be longer than equivalent durations of a filled interval. This finding was replicated when the anchor durations used during training were changed to 1 s and 4 s, or 4 s and 16 s. 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. In addition, the difference limens (DL) for empty intervals were smaller than those for filled intervals, and they also increased as the magnitude of anchor duration pairs increased. An analysis of the Weber fractions (WF; i.e., DL/PSE) provided evidence for superimposition of the empty and filled timing functions across the different sets of anchor durations. These results suggest that the accumulation of subjective time was greater for empty intervals than for filled intervals. Within the framework of scalar timing theory, this difference in timing appeared to be the result of a clock rate difference rather than a switch latency difference.The ability of humans and animals to perceive and remember time has often been investigated with a temporal bisection procedure. In this procedure, subjects are trained to choose between two responses ("short" or "long") following one of two training durations. Once a high level of accuracy is achieved, intermediate durations are introduced, but responses on these trials are not reinforced. From this procedure, a psychophysical function can be generated, and the point of subjective equality (PSE) can be calculated. The PSE is the value on the time dimension at which the subject displays indifference between choosing the "short" or the "long" response. Although studies with animals (Church & Deluty, 1977;Gibbon, 1986)

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

“…In addition, the empty-filled difference in timing should be greater for psychophysical tests conducted with the 4-versus 16-sec anchor durations than for the 2-versus 8-sec anchor durations. This will replicate an important previous result (Miki & Santi, 2005) indicating that dif-f f ferent sets of anchor durations produce a multiplicative timing difference rather than an additive timing difference. Additive timing differences are typically attributed to timing latency effects, whereas multiplicative timing differences are attributed to clock-rate differences (see Penney, Gibbon, & Meck, 2000;Wearden, Edwards, Fakhri, & Percival, 1998).…”

“…Only recently has this topic been systematically investigated in animals. Miki and Santi (2005) trained pigeons in a within-subjects design to discriminate empty intervals (short or long durations bound by two 500-msec light markers) and filled intervals (short or long durations of a continuous visual signal). Empty intervals required a response to one set of colored comparisons, and filled intervals required a response to a different set of colored comparisons.…”

Differences in duration discrimination of filled and empty auditory intervals as a function of base duration

“…Because of the large number of highly ambiguous results, in his comp prehensive reviews of the influence of filled and empty intervals on performance on duration discrimination in humans, Grondin (2001Grondin ( , 2003 arrived at the conclusion that, to date, no definitive statement on this issue can be made. Most interestingly, similarly inconclusive results have been reported from animal studies (e.g., Kraemer, Randall, & Brown, 1997;MacInnis, 2007;Miki & Santi, 2005;Santi, Keough, Gagne, & van Rooyen, 2007;Santi, Miki, Hornyak, & Eidse, 2006). At this point, it seems that differences in duration discrimination with filled and empty intervals may depend on various factors, such as the duration of the intervals to be compared, the sensory y p , p y modality in which the intervals are presented, the physical characteristics of the markers defining the empty intervals, or the psychophysical procedure applied (cf.…”

Slowing Down the Clock: A Review of Experimental Studies Investigating Psychological Time Dilation

“…These criteria excluded (see Figure 1): (1) experiments using time judgment durations shorter than 1 second (e.g., Aubry, Guillaume, Mogicato, Bergeret, & Celsis, 2008), animals (e.g., Miki & Santi, 2005), participants exhibiting psychopathology (e.g., Rueda & SchmitterEdgecombe, 2009), participants experiencing an unusual physical condition (e.g., Cheng, Ali, & Meck, 2007, or those in an altered state of consciousness (e.g., Bowers & Brenneman, 1979); (2) studies that used bisection or temporal generalisation methods, or experiments in which participants made qualitative judgments (e.g., Grondin & McAuley, 2009); (3) studies that did not report an adequate level of statistics to compute the effects sizes or the the subjective/objective ratio (e.g., Block & Reed, 1978); and, (4) studies in which researchers did not obtain and report a perceived time dilation(e.g., Hellsrtom & Carlsson, 1997) (see Figure 1). …”