Multiple-interval timing in rats: Performance on two-valued mixed fixed-interval schedules

Abstract

Three experiments studied timing in rats on two-valued mixed-FI schedules, with equally probable components, FI S and FI L. When the L/S ratio was greater than 4, two distinct response peaks appeared close to FI S and L, and data could be well-fitted by the sum of 2 Gaussian curves. When the L/S ratio was less than 4, only one response peak was visible, but nonlinear regression usually identified separate sources of behavioral control, by FI S and FI L, although control by FI L dominated. The data were used to test ideas derived from Scalar Expectancy Theory (SET), the Behavioral Theory of Timing (BeT), and Learning to Time (LeT)