Animals prefer reinforcement that follows greater effort: Justification of effort or within-trial contrast?

Abstract

Justification of effort by humans is a form of reducing cognitive dissonance by enhancing the value of rewards when they are more difficult to obtain. Presumably, assigning greater value to rewards provides justification for the greater effort needed to obtain them. We have found such effects in adult humans and children with a highly controlled laboratory task. More importantly, under various conditions we have found similar effects in pigeons, animals not typically thought to need to justify their behavior to themselves or others. To account for these results, we have proposed a mechanism based on within-trial contrast between the end of the effort and the reinforcement (or the signal for reinforcement) that follows. This model predicts that any relatively aversive event can serve to enhance the value of the reward that follows it, simply through the contrast between those two events. In support of this general model, we have found this effect in pigeons when the prior event consists of: (a) more rather than less effort (pecking), (b) a long rather than a short delay, and (c) the absence of food rather than food. We also show that within-trial contrast can occur in the absence of relative delay reduction theory. Contrast of this kind may also play a role in other social psychological phenomena that have been interpreted in terms of cognitive dissonance. Keywords: cognitive dissonance, justification of effort, contrast, delay reduction When humans behave in a way that is inconsistent with the way they think they should behave, they will often try to justify their behavior by altering their beliefs. The theory on which this behavior is based is known as cognitive dissonance theory (Festinger, 1957). Evidence for the attempt to reduce cognitive dissonance comes from the classic study by Festinger and Carlsmith (1959) who found that subjects, who were given a small reward for agreeing to tell a prospective subject that a boring task was interesting, then rated the task more interesting than subjects who were given a large reward. Presumably, those given a small reward could not

Effects of effort and difficulty on human preference for a stimulus: Investigation of the within-trial contrast

“…For example, Aronson and Mills (1959) manipulated task difficult and reported that participants who were required to read some embarrassing sexual descriptions in order to join a discussion group placed greater value on the group as the severity of the required task increased. Recently, a similar phenomenon has been reported in nonhuman animals (Zentall, 2013). A series of studies beginning with Clement, Feltus, Kaiser, and Zentall (2000) has examined whether there are differences in preferences for outcomes that follow two kinds of preceding tasks involving different efforts.…”

“…They found that although the preference for the following stimuli became greater with increased amounts of training, the direction of the preference was inconsistent with the prediction based on the WTC. These studies have provided evidence about the boundary conditions of the WTC, and also gave rise to an argument about procedural variables (e.g., Zentall, 2013;Zentall & Singer, 2007). As one of the main procedural variables, the preceding tasks were not sufficiently aversive events for the individuals (Zentall, 2013).…”

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Abstract The within-trial contrast hypothesis (WTC) provides a more parsimonious explanation for the phenomenon that humans and animals prefer outcomes that follow more effortful events to outcomes that follow less effortful events (Zentall, 2013). We conducted two WTC experiments with human adults.

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“…These studies have provided evidence about the boundary conditions of the WTC, and also gave rise to an argument about procedural variables (e.g., Zentall, 2013;Zentall & Singer, 2007). As one of the main procedural variables, the preceding tasks were not sufficiently aversive events for the individuals (Zentall, 2013). In Arantes and Grace (2008), they used 20 pecks as an effortful requirement, and their pigeons had prior experience with a variableinterval schedule (VI).…”

“…It is known that VI is designed to produce a constant rate of response (Ferster & Skinner, 1957). Thus, the 20 pecks that served as an effortful event were less likely to arouse an aversive state for the pigeons that had previously performed on a VI (Zentall, 2013).…”