Association for Behavior Analysis International

Research investigating self-control often focuses on choice between two desirable outcomes – those in which an individual can produce either a small outcome delayed by short amount of time or a large outcome delayed by a long time; however, individuals encounter another kind of choice situation in daily life – one in which a choice can produce both desirable and undesirable outcomes. The present symposium arranges three recent studies that attempt to further our understanding of self-controlled choice in situations involving both desirable and undesirable outcomes. The goal of this symposium is to explore recent approaches to investigate this type of choice situation and to encourage future research on this underrepresented area.

Some problematic human behavior occurs when a single choice produces reinforcing and aversive consequences. The present experiments explored this type of choice situation using rats to investigate how the value of an immediate food reinforcer that is followed by a shock changes as a function of the delay to the shock. The rats chose between two food pellets delivered immediately and followed by delayed shock, and two food pellets delivered alone after a delay. Within each condition, the delay to food was adjusted based on each rat’s previous choices until both consequences were chosen equally often and the delay to food was stable. At this “indifference point,” the delayed food was equal in value to the immediate food followed by shock. Depending on the experiment, either the delay to shock or whether the delayed shock was signaled was manipulated across conditions. Generally, the shock devalued the immediate food to the greatest extent when the delay to shock was short. As the delay to shock was raised, these effects weakened in a pattern resembling a hyperbola. The signaling procedure did not affect the value of the immediate food systematically. The findings parallel research on temporal discounting of positive reinforcers.

In contrast to the large amount of studies of temporal discounting of positive consequences, research on temporal discounting of aversive consequences is scarce. For this reason, we developed a procedure for studying in rats the temporal discounting of aversive consequences, whose rationale and main results are presented next. In the first phase, rats chose between one-pellet and four-pellet alternatives; when subjects developed preference for the larger-amount alternative, an electric shock was added to it, resulting in a loss of preference. In the second phase, the delay to shock was progressively increased within each session (ascending delays: 0, 5, 10, 20, 40 s), which resulted in a recovery of preference for the larger-amount-plus-shock alternative as delay was increased. In a third phase, with the aim of analyzing whether the previous result was influenced by short-term habituation to the shock rather than to temporal discounting, the order of delays was reverted so that they were presented in descending order. As in the previous phase, rats showed a higher preference for the larger-amount-plus-shock alternative when delay was larger, indicating that habituation did not play a major role in this procedure. Currently, we are using this procedure to: a) analyze the impact of the intensity of the shock on the discount function, and b) evaluate the temporal discounting of aversive consequences in spontaneously hypertensive rats -a purported animal model of ADHD-, in order to complement the extensive research on temporal discounting of positive reinforcers that has been performed with this strain.