Volition in Prospective Memory: evidence against differences in recalling free and fixed delayed intentions

Human volition can be defined as the extent to which actions are generated by internal states or as a response to externally dictated instructions. Whether actions are voluntary or not influence the cognitive process of action generation and perception of action. The influence of volition on deciding actions at a later point in time is a less explored dimension. A voluntary decision on future action requires that the intention must be stored in the prospective memory until the intended action is performed. It is unknown if the distinction between freely chosen actions and externally dictated actions has a cognitive relevance for delayed intentions. In the present study, we compare the difference between voluntarily formed intentions and intentions fixed by external instructions in a prospective memory task. In the task, participants either freely chose a cue or were given a fixed cue by the task instructions which they had to store in memory and recalled when the cue was encountered during an ongoing filler task. We examined if there would be a difference between the free and fixed delayed intention on retrieval of the delayed intention by modelling the task performance and reaction time using a Bayesian hierarchical drift-diffusion model. We then compared if there were differences in diffusion rate, decision threshold, bias, and non-decision time between free and fixed intentions in the prospective memory task, which would signify that free and fixed delayed intentions differentially engage prospective memory. Comparison of the estimated model parameters for the free and fixed intentions showed evidence against differences between free and fixed conditions in the prospective memory task. The results suggest that once the intention is encoded in memory, it no longer makes a cognitive difference at retrieval if it was initially formed freely or was fixed.