Analysis of impulsive choice: Assessing effects of implicit instructions

Abstract

College students exhibited impulsivity if, in the first of 2 sessions, they consistently chose an immediate, small reinforcer (15-s cartoon video followed by 75 s of waiting) over a delayed, large reinforcer (55-s prereinforcer delay, 25-s video, 10 additional s of waiting), or self-control if they showed the opposite preference. Previously, Navarick (2001) found that informing impulsive participants in Session 2 that the viewing time was longer on their nonpreferred schedule reduced impulsive choice to about .50; informing self-controlled participants that the video started sooner on their nonpreferred schedule had no effect. In addition to facilitating discrimination between reinforcers, the instructions to impulsive participants could have implied a request to choose the indicated schedule (a demand characteristic) or that the nonpreferred schedule was somehow more advantageous. Effects of these potentially implicit instructions were assessed by presenting them as explicit instructions to determine if they again produced a decrease in impulsive choices in impulsive participants and no change in self-controlled participants. In contrast to the previous pattern, impulsive and self-controlled participants conformed similarly to the experimenter’s stated schedule preference, and showed similar, variable preferences in response to the general schedule characterization. The previous instructions reduced impulsivity by facilitating discrimination between the large and small reinforcers and not by conveying these implicit messages.