Delay as Punishment in the Avoidance-reward Conflict Task in Non-human Primates

Introduction: Decision-making involves anticipating rewards and punishments. The avoidance-reward conflict (ARC) task evaluates decision-making processes in animals and humans. In non-human primates (NHPs), air puffs and juice rewards are commonly employed, with cue thickness indicating the probability of punishment or reward. However, using air puffs as punishment has limitations. This study uses delay as a form of punishment, with juice as a reward, to assess NHP behavior in the ARC task.

Methods: A rhesus monkey performed the ARC task in nine conditions, combining two cues, each signaling different probabilities of receiving juice and delay, each trial consisted of a fixation point, followed by a punishment cue, a combined punishment and reward cue, a go cue, and scene and sound feedback. The progressive ticker cue correlated with progressive low (10%), medium (50%), and high (90%) probabilities of receiving the outcome. Selecting the target in the right location means accepting the condition presented, while choosing any other target means discarding the condition. We considered the breaking fixation in punishment cue as an early break and in combination cues as a late break Data were analyzed for acceptance rate and reaction time (timing between appearing the go cue and response).

Results: Significant differences were observed between conditions in the rates of acceptance, rejection, and break trials (p < 0.01). The acceptance rate was highest in low-delay/high-juice conditions and lowest in high-delay/low-juice, and low-juice/medium delay conditions. Rejection rates were higher in high-delay/low-juice conditions. Cumulative acceptance rates and reaction times also varied significantly across conditions (p < 0.05, statistical test please here), with the longest reaction times for low-juice/ high-delay conditions and the shortest for low-delay/high-juice.

Conclusion : Delay effectively served as a punishment in the ARC task and influenced the NHP's decision-making. The animal was more likely to select conditions with a high probability of reward and to reject those with a low probability of reward or a high probability of delay. Reaction time analysis showed that more challenging conditions required longer decision times.