Association for Behavior Analysis International

Behavior analysis has focused on examining the effects of the consequences of behavior. However, evidence suggests that rats’ operant performance is attuned to the affordances that the operant setting provides, such as lever height. This presentation will cover two studies on rats’ progression from lever pressing acquisition to situations where lever pressing has been instrumentally conditioned. In experiment 1 lever pressing acquisition was examined in three groups of naïve rats, in each group lever height was set at 1, 11, or 18 cm-height. Response acquisition was faster at the 11-cm height lever group, and lever pressing latency was shorter with the 18-cm lever group. In experiment 2 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. Across conditions, preference between both levers changed showing a linear trend with increasing lever heights. Collectively, the research suggests that preorganized properties of behavior (i.e., the animal’s abilities) interact with the environment before operant learning emerges.

Compared to rate of discrete responding, response duration has received scant attention as a dependent measure in behavior analysis. We will present results from a series of recent experiments in which we studied the duration of lever-pressing in laboratory rats. In all of the investigations, we arranged the delivery of edible reinforcers if depressing a response lever fell under or exceeded a programmed interval. We will discuss three general findings in detail. First, response duration may present some advantages over response rate for studying the effects of delayed reinforcement. Second, response duration increases significantly during extinction. This occurs whether or not there has been a history of differential reinforcement for depressing the response lever. This has implications for the interpretation of resurgence when behavior has a salient duration dimension. And finally, arranging reinforcement for response duration results in chains of idiosyncratic responses that rats emit concurrently with lever pressing. Whether these responses should be operationally defined as lever pressing presents a conceptual challenge.

To examine the effects of the temporal separation of multiple VI VI schedule components on differential resistance to change (DRTC), two experiments were conducted with rats. Reinforcement rates and magnitudes (reinforcers per cycle) were manipulated in Experiments 1 and 2, respectively, to produce rich and lean components. In both experiments, the separation of the components was manipulated by using different component durations, during one condition, and different intercomponent intervals (ICI), during another condition. Total exposure to the components was constant across sessions of each condition. Resistance to satiation was evaluated by delivering increasing amounts of the reinforcer before each test session. In Experiment 1, different component duration either increased (F2 and F4), decreased (F1 and F02), or had no consistent effects (F3) on DRTC. Increasing ICIs produced either an increase (F02) or an increase followed by a decrease (i.e., an inverted U function) in DRTC. In Experiment 2, increases in component duration produced either an increase (F6 and F8) or no consistent effects on DRTC. Increasing ICIs produced an increase (F7) or an inverted U effect on DRTC. Results are discussed in terms of the discrimininability of contingencies that are too close or too separate in time.