Environmental dynamics modulate covariation of choice and timing

• Timing (start and stop times in no-food trials) was a function of fixed interval schedule in dynamic and static conditions.
• Choice (response allocation) was sensitive to relative reinforcer immediacy in static and dynamic conditions.
• Encoding error from measures of choice were more related to timing encoding error in dynamic than static conditions.
• Differences in encoding error correlations were not an artifact of range restriction.
• Results suggest dynamism plays a role in choice: animals use different decision strategies based on environmental dynamics.

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