The overjustification effect: A meta-analysis

This article reports the results of a meta-analysis using 50 experimental studies (256 effect sizes) of the overjustification effect. In general, we found support for the effect across age, dependent measure, and design type in specific situations where it is predicted to occur. Findings are less supportive of the theory for situations where there should be no difference between experimental and control groups (e. g. non-contingent or unexpected reward). Suggestions for future research are made.     

Competence and the overjustification effect

The overjustification effect is manifested in decreased interest in an activity as a result of having been rewarded for participation in the activity. According to attribution theory's discounting principle, decreased interest occurs because the subject discounts the role of intrinsic motivation when a salient extrinsic reward is present. An alternative analysis based on the competence principle suggests that only rewards that convey no message of competence foster the overjustification effect, while manipulations that do convey competence information do not. A study crossing Reward (no reward-monetary reward) and Task Difficulty (hard-easy) supported the competence analysis. Subjects who succeeded on the hard task and thus felt competent manifested higher subsequent interest in the task. Consistent with the competence analysis, presence or absence of reward did not influence subsequent interest in the task.This research has been supported by a grant from the Ohio University Research Fund. I am grateful to Mark Henault, who served very ably as the experimenter. The hard work of Joel Ghitman and Craig Alexander is also gratefully acknowledged.     

Reconceptualizing of the overjustification effect: A template-matching approach

The paper reviews traditional attributional explanations for the over-justification effect in task motivation, isolates their weaknesses, and proposes an alternative account based on the notion that individuals process task information schematically. It is proposed that task information relating to motivation is interpreted by cognitive schema or “templates,” which identify tasks as being either instrumental or expressive in nature. When the expressive template is evoked, the task is perceived to be playlike and is experienced as inherently motivating. When the instrumental template is evoked, the task is perceived as a means to an end and task motivation results from the perceived value of the task for attaining intrinsic and/or extrinsic rewards. Structural characteristics of these templates are proposed. According to this account, overjustification effects occur when the perceived characteristics of tasks change such that the expressive template is replaced by the instrumental template and expressive motivation is transformed into instrumental motivation.     

An evaluation of the overjustification effect across multiple contingency arrangements

The overjustification effect suggests that external rewards may decrease intrinsically reinforced behaviors; however, this conclusion is often drawn from pre‐ and post‐assessment data. The majority of studies published in this area do not take repeated measures of behavior. In addition, previous research has not distinguished between the use of rewards and reinforcers by demonstrating a reinforcement effect; hence, it is possible that the occurrence of the overjustification effect varies depending on the nature of the stimuli that are used. This study extended previous research by evaluating whether the overjustification effect was relevant to the use of non‐reinforcing stimuli, reinforcers, or both. The effects of verbal praise were also evaluated in relation to the overjustification effect. Results indicated that behavior did not decrease below baseline levels following the contingent delivery of non‐reinforcing stimuli, reinforcers, or verbal praise. Copyright © 2009 John Wiley & Sons, Ltd.     

Generic overjustification: The interaction of extrinsic rewards

An experiment was conducted to test the hypothesis that the value of one extrinsic reward will be undermined when another extrinsic reward is made contingent upon the same activity. Subjects were assigned to one of three experimental groups. Some were paid a contingent monetary reward for engaging in a monotonous and boring activity and were then given the opportunity to continue to work voluntarily for additional payment. Others were given both money and extra experimental credit for the required task, and were likewise offered additional pay for voluntary extra work. A third group of subjects received money for the required task, but were given no additional rewards for extra work. It was observed that the money + credit subjects did less extra work for pay than the money-only subjects. They also rated the monetary reward as having been of less value to them. Subjects who were paid during the initial task session but not for extra work did less additional work than those who were paid in both sessions, but did not differ in their ratings of the value of the monetary reward. It is concluded that extrinsic rewards are nonadditive, and that current models of undermined rewards are too limited to account for this phenomenon. A selective attention hypothesis is advanced as an alternative.     

On the self-perception explanation of the overjustification effect: The role of the salience of initial attitude

An experiment was conducted to examine the proposition, derived from self-perception theory, that the “overjustification” effect would be mitigated if initial attitudes toward the task were made salient. Children engaged in a target activity with or without the promise of reward for doing so. Half the children were shown a photograph of themselves freely engaging in the target activity in an earlier session so as to remind them of their intrinsic interest in the task. The other children were not shown such a photograph. Consistent with the predictions. expected reward decreased subsequent intrinsic interest only when initial attitudes were relatively nonsalient. The findings demonstrate the relevance of self-perception processes to the “overjustification” effect.     

Extending overjustification: the effect of perceived reward-giver intention on response to rewards

The perceived intention model incorporates a new moderator, beliefs about reward-giver intention, into the overjustification paradigm. In 2 simulated shopping studies featuring products paired with promotional rewards, consumers who believed the marketer was promotion focused (reward used to encourage purchase) reported lower purchase intentions and brand attitudes for promoted products after promotion, whereas consumers who believed the marketer was reward focused (promotion used to distribute the reward) showed no attitude change. Promotion-focus beliefs lowered attitudes by heightening the contingency between the promotion and purchase and thereby increasing the perceived causal role of the reward. This effect was contingent on initial behavior--postpromotion attitude change occurred for consumers who actively engaged in product decisions but not for consumers who passively observed the choice sets.     

The influence of incentive-aroused ambivalence on overjustification effects in attitude change

Rewarding people to advocate a position with which they already agree can undermine their attitudinal positivity. This research tests a novel explanation of this example of the overjustification phenomenon. The hypothesis holds that the provision of an unnecessary incentive gives rise to an ambivalent response: the positive reaction to the reinforcement is accompanied by a sense of uneasiness, or apprehension, regarding the legitimacy of the induced behaviors. Attitude change is expected only in circumstances that confirm the apprehension. Results consistent with this expectation were discovered. In Study 1, respondents asked to play the role of a subject in an overjustification experiment reported greater levels of ambivalence regarding their (role-played) proattitudinal action as a function of payment. Contrary to alternative interpretations of the phenomenon, no incentive-related differences were found in subjects' ratings of the reprehensibility of the requested action, or in their beliefs that future activities of the type requested be undertaken only for payment. In Study 2, subjects paid to read a proattitudinal speech were found subsequently to be less in favor of their original positions only if they also had been given a counterattitudinal communication. The presence or absence of the countercommunication had no influence on the attitudes of unpaid respondents. Subjects for whom the payment was made to appear incidental to the experiment did not demonstrate the usual overjustification effect. These results supported the incentive-aroused ambivalence hypothesis. Psychological mechanisms that might underlie the effect were discussed.     

Progressing from programmatic to discovery research: a case example with the overjustification effect

Scientific research progresses along planned (programmatic research) and unplanned (discovery research) paths. In the current investigation, we attempted to conduct a single-case evaluation of the overjustification effect (i.e., programmatic research). Results of the initial analysis were contrary to the overjustification hypothesis in that removal of the reward contingency produced an increase in responding. Based on this unexpected finding, we conducted subsequent analyses to further evaluate the mechanisms underlying these results (i.e., discovery research). Results of the additional analyses suggested that the reward contingency functioned as punishment (because the participant preferred the task to the rewards) and that withdrawal of the contingency produced punishment contrast.     

Undermining overjustification: Inducing intrinsic and extrinsic task representations

A study was conducted to test the proposition that the overjustification effect is a result of the interaction of two distinct task interpretations. It was argued that intrinsic and extrinsic motives might best be viewed as cognitive representations of task situations involving multiple task associates. It was predicted that by altering the salience of intrinsic and extrinsic task information, it would be possible to change the effects of an extrinsic reward on intrinsic motivation. The results indicated that when task rewards were interpreted from within an intrinsic task representation, they did not undermine an individual's free-choice task activity. The results are discussed in terms of recent work in cognitive psychology.     

A quantitative review of overjustification effects in persons with intellectual and developmental disabilities

The overjustification hypothesis suggests that extrinsic rewards undermine intrinsic motivation. Extrinsic rewards are common in strengthening behavior in persons with intellectual and developmental disabilities; we examined overjustification effects in this context. A literature search yielded 65 data sets permitting comparison of responding during an initial no‐reinforcement phase to a subsequent no‐reinforcement phase, separated by a reinforcement phase. We used effect sizes to compare response levels in these two no‐reinforcement phases. Overall, the mean effect size did not differ from zero; levels in the second no‐reinforcement phase were equally likely to be higher or lower than in the first. However, in contrast to the overjustification hypothesis, levels were higher in the second no‐reinforcement phase when comparing the single no‐reinforcement sessions immediately before and after reinforcement. Outcomes consistent with the overjustification hypothesis were somewhat more likely when the target behavior occurred at relatively higher levels prior to reinforcement.     

The body-inversion effect

Researchers argue that faces are recognized via the configuration of their parts. An important behavioral finding supporting this claim is the face-inversion effect, in which inversion impairs recognition of faces more than nonface objects. Until recently, faces were the only class of objects producing the inversion effect for untrained individuals. This study investigated whether the inversion effect extends to human body positions, a class of objects whose exemplars are structurally similar to each other. Three experiments compared the recognition of upright and inverted faces, houses, and body positions using a forced-choice, same/different paradigm. For both reaction time and error data, the recognition of possible human body postures was more affected by inversion than the recognition of houses. Further, the recognition of possible human body postures and recognition of faces showed similar effects of inversion. The inversion effect was diminished for impossible body positions that violated the biomechanical constraints of human bodies. These data suggest that human body positions, like faces, may be processed configurally by untrained viewers.     

The mirror effect and the spacing effect

In the mirror effect, there are fewer false negatives (misses) and false positives (false alarms) for rare (low-frequency) words than for common (high-frequency) words. In the spacing effect, recognition accuracy is positively related to the interval (spacing or lag) between two presentations of an item. These effects are related in that they are both manifestations of a leapfrog effect (a weaker item jumps over a stronger item). They seem to be puzzles for traditional strength theory and at least some current global-matching models. A computational strength-based model (EICL) is proposed that incorporates excitation, inhibition, and a closed-loop learning algorithm. The model consists of three nonlinear coupled stochastic difference equations, one each for excitation (x), inhibition (y), and context (z). Strength is the algebraic sum (i.e., s = x − y + z). These equations are used to form a toy lexicon that serves as a basis for the experimental manipulations. The model can simulate the mirror effect forcedchoice inequalities and the spacing effect for single-item recognition, all parameters are random variables, and the same parameter values are used for both the mirror and the spacing effects. No parameter values varied with the independent variables (word frequency for the mirror effect, lag for the spacing effect), so the model, not the parameters, is doing the work.     

The acoustic similarity effect

The latency of reading 5-word sequences of 3 levels of acoustic similarity was measured. Highly similar sequences were found to have longer latencies than sequences of low similarity or control sequences. The implications of this finding for the acoustic similarity effect in STM are discussed.     

The foreperiod effect revisited

This paper explores four factors which could be important in accounting for the discrepant results which have previously been obtained with respect to the effect of foreperiod duration on reaction time (RT). In some studies a clear effect of foreperiod duration on auditory RT has been found, in contrast to a recent finding that foreperiod duration affected visual RT but not auditory RT. By means of two experiments, the effects of practice, time-on-task, reaction task (a-reaction versus selective reaction) and signal intensity were studied. The latter variable appears to be the principal determinant of the discrepant results in that there is an interaction between signal intensity, foreperiod duration and modality. The results fit the hypothesis that signals beyond a given intensity exert an immediate arousing effect which counteracts the foreperiod effect.     

The metacognitive disambiguation effect

From an early age, children show a tendency to map novel labels onto unfamiliar rather than familiar kinds of objects. Accounts of this tendency have not addressed whether children develop a metacognitive representation of what they are doing. In 3 experiments (each N = 48), preschoolers received a test of the metacognitive disambiguation effect, which involved deciding whether the referent of a novel label was located in a bucket of things “I know” or bucket of things “I don’t know.” Most 4-year-olds passed this test, whereas most 3-year-olds did not. Children’s performance was predicted by their ability to report whether various words and pseudowords were ones that they knew, even after age and vocabulary size were controlled. As children develop an awareness of their lexical knowledge/ignorance, they also develop a metacognitive representation of their tendency to map novel labels onto unfamiliar rather than familiar kinds.