Pigeons flexibly time or count on cue

In Experiment 1, pigeons were presented with a sequence of light flashes an d cued to peck a key for reward either after a fixed time or after a fixed number of flashes. Curves that showed the rate of key pecking over time wit hin trials indicated that peak rates of response were reached near the fixe d time on timing-cued trials and near the fixed number of flashes on counti ng-cued trials. In Experiment 2, the key cue was shifted from timing to cou nting or from counting to timing midway through a trial. The peak times rea ched reached after the cue change indicated that pigeons kept track of time while cued to count but did not count while cued to time. These findings s uggest a basic asymmetry in the dual-mode model of timing and counting.