Understanding the effects of motivation on
instrumental action selection, and specifically on its two main forms,
goal-directed and habitual control, is fundamental to the study of
decision making. Motivational states have been shown to 'direct'
goal-directed behavior rather straightforwardly towards more valuable
outcomes. However, how motivational states can influence
outcome-insensitive habitual behavior is more mysterious. We adopt a
normative perspective, assuming that animals seek to maximize the
utilities they achieve, and viewing motivation as a mapping from outcomes
to utilities. We suggest that habitual action selection can direct
responding properly only in motivational states which pertained during
behavioral training. However, in novel states, we propose that
outcome-independent, global effects of the utilities can 'energize'
habitual actions.