Actions and habits: the development of behavioural autonomy

The study of animal behaviour has been dominated by two general models. According to the mechanistic stimulus-response model, a particular behaviour is either an innate or an acquired habit which is simply triggered by the appropriate stimulus. By contrast, the teleological model argues that, at least, some activities are purposive actions controlled by the current value of their goals through knowledge about the instrumental relations between the actions and their consequences. The type of control over any particular behaviour can be determined by a goal revaluation procedure. If the anim al’s performance changes appropriately following an alteration in the value of the goal or reward without further experience of the instrumental relationship, the behaviour should be regarded as a purposive action. On the other hand, the stimulus-response model is more appropriate for an activity whose performance is autonomous of the current value of the goal. By using this assay, we have found that a simple food-rewarded activity is sensitive to reward devaluation in rats following limited but not extended training. The development of this behavioural autonomy with extended training appears to depend not upon the am ount of training per se, but rather upon the fact that the animal no longer experiences the correlation between variations in performance and variations in the associated consequences during overtraining. In agreement with this idea, limited exposure to an instrumental relationship that arranges a low correlation between performance and reward rates also favours the development of behavioural autonomy. Thus, the same activity can be either an action or a habit depending upon the type of training it has received.