Asymmetric effects of signal intensity on timing behavior in the peak-interval procedure

The peak-interval procedure is one of the most widely used paradigms to assess interval timing in animal models, and disruptions in performance are commonly interpreted as disruptions in the timing mechanism. The time-sharing model (TSM) accounts for such changes by proposing that attentional resources are shared between temporal processing and the processing of novel events, producing pulse loss in the accumulator and leading to rightward shifts in peak time and decreases in response rate. According to the TSM, sustained changes in the temporal cue should induce continuous pulse loss and a marked degradation of temporal control. The present study tested these predictions by exposing pigeons to a peak-interval procedure in which the intensity of the temporal cue was parametrically varied throughout the trial. In Experiment 1, increases in signal intensity preserved response distributions centered near the trained interval, albeit with increased dispersion, whereas decreases in intensity produced irregular distributions, greater divergence from baseline performance, and longer response latencies. Experiment 2 showed that pigeons can acquire and maintain temporal control under low-intensity signals when explicitly trained, while preserving the same asymmetry between intensity increments and decrements. Together, these findings are not fully consistent with the predictions of the TSM and indicate that parametric variations in signal intensity primarily modulate the likelihood and consistency with which timing behavior is expressed. These results highlight the importance of considering nontiming behaviors, motivational factors, and variability when interpreting performance in peak-interval procedures and suggest the consideration of a dissociative modular hypothesis of performance as a complementary framework. (PsycInfo Database Record (c) 2026 APA, all rights reserved).