The ability of two internal clock models to predict performance on a temporal bisection task

This research tested the ability of two competing models of animal timing, Learning to Time (LET) and Scalar Expectancy Theory (SET), to predict hens' performance on a temporal bisection task, in a replication of an experiment by Machado and Keen (1999). Hens were trained in two temporal discriminations; in Type 1 trials they learned to choose a red key after a 1-s signal and a green key after a 4-s signal and in Type 2 trials they learned to choose a green key after a 4-s signal, and a yellow key after a 16-s signal. After they learnt these discriminations, intermediate durations were presented. The resulting psychometric function did not superpose, violating the scalar property of timing. When novel key and duration combinations were presented and performance on subsequent generalisation tests closely matched LETS predictions. Overall, the results support the findings of Machado and Keen (1999) and supported LET's rather than SET's predictions.