Delay discounting of hypothetical monetary rewards with decoys

The current research attempted to decrease individuals' rates of delay discounting by introducing decoys that are similar but inferior to delayed rewards. Two experiments in the current study compared patterns of delay discounting generated by repeated choices between two hypothetical monetary rewards in the absence or presence of a decoy. Binary questionnaires (i.e., decoy absent) included questions with two options: a smaller-sooner (SS) reward and a larger-later (LL) reward. Trinary questionnaires (i.e., decoy present) included questions with three options: an SS reward, an LL reward, and a decoy. If an option is at least as rewarding on every dimension of value as an alternative and the option is more rewarding than an alternative on at least one dimension, then the option is considered to dominate the alternative (Wedell, 1991). The first experiment assessed the influence of decoys dominated by LL rewards (LL(-) decoys), which were constructed to be similar (on the dimension of amount) but inferior (on the dimension of delay) to LL rewards. The second experiment examined the effects of counterbalancing the order of binary and trinary questionnaires. In the first experiment, participants discounted to a lesser degree when LL(-) decoys were present as compared to when they were absent. In the second experiment, participants only discounted to a lesser degree on trinary questionnaires with LL(-) decoys when they had not previously completed binary questionnaires. Patterns of discounting generated by binary questionnaires were similar to those generated by trinary questionnaires when decoys are present; however, the degree to which individuals discounted delayed rewards was affected by the number of and type of options that were available. The current results join previous evidence suggesting that rates of delay discounting are sensitive to a variety of contextual influences.