Decision-making and action selection in Two Minds: An analysis based on Model Human Processor with Realtime Constraints (MHP/RT)

Decision-making and action selection are mental activities for shaping and organizing human behavior in the ever-changing environment. There are, however, important differences between decision-making and action selection. According to “Two Minds” (Evans and Frankish, 2009, Kahneman, 2003, Kahneman, 2011) - a version of dual processing theory - human behavior can be viewed as the integration of output of System 1, i.e., unconscious automatic processes, and System 2, i.e., conscious deliberate processes. System 1 activates a sequence of automatic actions. System 2 monitors System 1's performance according to the plan it has created and, at the same time, it activates future possible courses of actions. Decision-making narrowly refers to System 2's slow functions for planning for the future and related deliberate activities, e.g., monitoring, for future planning. On the other hand, action selection refers to integrated activities including not only System 1's fast activities but also System 2's slow activities, not separately but integrally. This paper further discusses the difference between decision-making and action selection on the basis of the architecture model the authors have developed for simulating human beings' in situ action selection, Model Human Processor with Realtime Constraints (MHP/RT) (Kitajima & Toyota, 2012b). MHP/RT's simulation of human behavior along the time dimension shows when the processes of decision-making and action selection would be initiated and how they are carried out.