Environmental dynamics modulate covariation of choice and timing

Response allocation between delayed reinforcers is presumably a function of the discrimination of thosedelays. In the present experiment, we analyzed the functional relation between response allocation andtemporal discrimination across different environmental dynamics. Three pigeons pecked for food in aconcurrent-chain schedule. Concurrent variable-interval initial links produced fixed-interval (FI) termi-nal links. Start and stop times, single-trial measures of temporal discrimination, were obtained fromoccasional ‘no-food’ terminal links. In dynamic, rapid-acquisition conditions, terminal links were FI 10 sand 20 s and the location of the initial link leading to the shorter terminal link varied unpredictably acrosssessions. In the static conditions, both terminal links were either “uniform” FI 15-s schedules or one termi-nal link was “fixed” at FI 10 s and the other at 20 s. Response allocation and start and stop times adjustedwithin sessions in dynamic conditions and across sessions of static conditions. Residuals from regres-sions of expected on programmed immediacy ratios were positively correlated to a greater magnitudein dynamic than static conditions. This change in residual covariation demonstrated that environmentaldynamics modulated the relation between choice and timing.