The Role of Mixed Versus Consistent Reinforcers in Habit Development

Instrumental behaviors can be divided into two categories: goal-directed actions and habits. While goal-directed actions are sensitive to the current value of a reinforcer, habitual behaviors will continue once a reinforcer has been devalued. When tested in extinction, habitual behaviors will be performed at comparable rates regardless of the value of the reinforcer. In a series of two experiments, we examined how receiving Mixed (sucrose and grain pellets) versus Consistent (sucrose or grain pellets) reinforcers would affect the development of habit in a free-operant condition. Experiment 2 replicated Experiment 1 with a 20% increase in training time and the introduction of two (as opposed to one) daily training sessions. In both experiments, rat subjects received either Mixed or Consistent reinforcers during acquisition of a lever pressing behavior. The reinforcers were then devalued using a taste-aversion procedure. The rats\u27 lever pressing behaviors were tested in extinction. In Experiment 1, all groups exhibited goal-oriented behavior. In Experiment 2, all groups exhibited habitual behavior. Taken together these results suggest that receiving Mixed versus Consistent appetitive reinforcers does not impact the development of habit in free-operant conditions