Dynamics of pre- and post-choice behaviour: rats approximate optimal strategy in a discrete-trial decision task

Abstract

We simulate two types of environments to investigate how closely rats approximate optimal foraging. Rats initiated a trial where they chose between two spouts for sucrose, which was delivered at distinct probabilities. The discrete trial procedure used allowed us to observe the relationship between choice proportions, response latencies and obtained rewards. Our results show that rats approximate the optimal strategy across a range of environments that differ in the average probability of reward as well as the dynamics of the depletion-renewal cycle. We found that the constituent components of a single choice differentially reflect environmental contingencies. Post-choice behaviour, measured as the duration of time rats spent licking at the spouts on unrewarded trials, was the most sensitive index of environmental variables, adjusting most rapidly to changes in the environment. These findings have implications for the role of confidence in choice outcomes for guiding future choices.

Behavioral correlates of the decision process in a dynamic environment: post-choice latencies reflect relative value and choice evaluation

“…Asymmetrical effects of increases versus decreases of reward probabilities were also apparent in spout sampling durations. These durations can be an index of choice confidence and our previous work has found this to be a robust and sensitive measure of choice preference (Lavan et al, 2011 ; Fam et al, 2015 ). Here, we found that changes in spout sampling durations between High and Low tracked the changes in reward probabilities across the three phases.…”

“…An additional constraint was that each phase had a maximum length of five sessions in the event that rats failed to reach criteria levels of performance. The choice of five sessions was based on our previous work where we found that rats made behavioral adjustments within 5 sessions following contingency reversal (Lavan et al, 2011 ; Fam et al, 2015 ). Constraining the session length was important for ensuring that rats would not have vastly different levels of experience with phase contingencies.…”

“…Results are reported according to the spout status during phase two (High or Low). In addition to choice allocation, we focus on three response latency measures which our previous work has shown to be sensitive to reward contingencies (Fam et al, 2015 ). These were: choice execution latency (duration between leaving the nose-poke and first contact with a reward spout), spout sampling duration (time between first and last reward spout contact on unrewarded trials) and trial initiation latency (duration between last spout contact and arrival at nose-poke).…”

“…The discrete trial structure used here allowed us to decompose a single choice into three distinct components with which we could examine behavioral latencies as an index of choice behavior. Our previous work has shown that choice execution latencies (duration between leaving the nose-poke and first contact with a reward spout), spout sampling durations (time between first and last reward spout contact on unrewarded trials) and trial initiation latencies (duration between last spout contact and arrival at nose-poke) are sensitive to reward contingencies (Fam et al, 2015 ). In particular, we found spout sampling durations to be the most sensitive and consistent index of changes in reward probabilities (Lavan et al, 2011 ; Fam et al, 2015 ).…”

Temporal dynamics of choice behavior in rats and humans: an examination of pre- and post-choice latencies

“…These behavioral correlates of choice were compared between rats and humans, in addition to comparing differences in choice allocation. Our previous work found response latencies to be informative beyond choice allocation as to how environmental contingencies shape mechanisms underlying choice 20 21 22 . Specifically, we proposed that pre-choice latencies reflected outcome (i.e.…”