The present study investigates the influence of unpredictable perceptual and central decision processing difficulties on task choice and performance when tasks are either freely chosen or assigned. In Experiments 1 and 2, perceptual processing difficulty varied by altering colored dot proportions (easy vs. hard color discrimination task). In Experiment 3, decision processing difficulty was adjusted by changing the rotation degree of letters (easy vs. hard letter rotation task). Participants adjusted their task choices towards tasks with easier stimuli when perceptual difficulty varied, but decision difficulty showed minimal, if any, impact on choices. Considering also the free-choice performance results of the task with equal difficulty, the combined findings suggest a model in which, after some parallel perceptual processing, a task is selected before more serial central processing continues. Moreover, across all experiments, both free-choice and forced-choice performance were more impaired when responding to a harder stimulus than to an easier
one, but this effect was generally less pronounced in freely chosen tasks. This suggests that free task choices enable a more stable processing mode, making people less affected by variations in information difficulty and this notion is further supported by exploratory diffusion modeling results. Overall, we propose that some advantages of free-task over forced-task behavior are that people can avoid more difficult tasks by adjusting their choices in response to varying perceptual processing difficulties, and that processing in free-choice tasks is generally less affected by environmental changes, presumably due to a more robust internal representation of a freely chosen task goal.