Rats Engage in Suboptimal Choice When the Delay to Food Is Sufficiently Long

Numerous examples in the decision-making literature demonstrate that animals sometimes make choices that are not in their long-term best interest. One particular example finds pigeons preferring a low-probability alternative in lieu of a high-probability alternative, referred to as suboptimal choice. Although there is ample evidence that pigeons engage in such suboptimal choice, there is currently weak evidence (at best) that rats also do so. Cunningham and Shahan's (2018) temporal information-theoretic model suggests that suboptimal choice in pigeons arises when (1) the low-probability alternative provides stimuli that convey more temporal information than stimuli associated with the high-probability alternative and (2) when the delay to food is much longer relative to the delay to temporally informative signals at the choice point. The latter condition plays the important role of biasing decision making to be governed by the relative temporal information conveyed by stimuli rather than the relative rate of food delivery. The present experiment explored the possibility that rats will engage in suboptimal choice if the delay to food at the choice point is sufficiently long, as the temporal information-theoretic model suggests. Rats were given a choice between a suboptimal alternative providing food 20% of the time and an optimal alternative providing food 50% of the time. The suboptimal alternative provided stimuli that differentially signaled choice outcomes whereas the optimal alternative did not. The postchoice delay was manipulated across conditions and ranged from 10 s to 50 s. As with previous research, rats did not engage in suboptimal choice when the postchoice delay was 10 s. However, once the delay was at least 30 s, rats engaged in suboptimal choice. These results are consistent with the temporal information-theoretic model of suboptimal choice and suggest that rats and pigeons likely do not differ in the decision-making processes involved in the suboptimal choice procedure.