Affordances Guide Choice Behavior Between Equal Schedules of Reinforcement in Rats

Operant choice theories pose that behavior distribution between options is ruled by the consequences related with these options. Evidence suggests that rats? performance is attuned to the affordances that the operant setting provides, such as lever height. Our aim was to explore in rats whether lever press distribution was influenced by the affordances furnished by two levers. Lever pressing was reinforced in two concurrent equal variable-ratio schedules of reinforcement, and in successive conditions lever height was varied asymmetrically?that is, one lever was higher than the other. Results showed a quadratic relation between response rates and lever height, a linear trend between preference and lever height, and higher between- and within-bout response rates on the lower lever in four out of the six pairs of lever heights assessed. These findings suggest that intermediate lever heights favored lever pressing with faster bout initiation and faster within-bout responding, and support the idea that preorganized properties of behavior (i.e., the organism?s abilities) interact with the environment before the operant contingency takes place.