Eating for pleasure or profit: the effect of incentives on children's enjoyment of vegetables

Parents commonly use rewards to encourage children to eat healthfully, but this practice remains controversial because rewards are suspected of undermining children's intrinsic motivation. A cluster-randomized trial examined children's acceptance of a disliked vegetable over 12 daily taste exposures. These exposures were paired with a tangible reward, a social reward, or no reward, and the findings were compared with the results from a no-treatment control condition. Liking and intake of the vegetable were assessed in a free-choice consumption task at preintervention, postintervention, 1 month after intervention, and 3 months after intervention. Liking increased more in the three intervention conditions than in the control condition, and there were no significant differences between the intervention conditions. These effects were maintained at follow-up. Children in both reward conditions increased consumption, and these effects were maintained for 3 months; however, the effects of exposure with no reward became nonsignificant by 3 months. These results indicate that external rewards do not necessarily produce negative effects and may be useful in promoting healthful eating.     

Causality orientations moderate the undermining effect of rewards on intrinsic motivation

The present study tested the hypothesis that individual differences in autonomy or control causality orientation would moderate the undermining effect of rewards on intrinsic motivation. Equal numbers of autonomy- and control-orientated participants provided solutions to an interesting puzzle under reward or no reward conditions. Participants were then required to provide further solutions to the puzzle in a free-choice period. The time spent in solving the puzzle during the free-choice period constituted the dependent measure of intrinsic motivation. Results revealed a significant interaction effect of causality orientations and reward condition on intrinsic motivation. Control-oriented participants assigned to the reward condition exhibited significantly lower levels of intrinsic motivation compared to those assigned to the no reward condition. In contrast, there was no significant difference in intrinsic motivation levels across the reward conditions for autonomy-oriented individuals. Findings indicate that an autonomy-oriented causality orientation offered a degree of ‘protection’ from the undermining effect of rewards on intrinsic motivation. This is in keeping with self-determination theory in terms of the interactive effects of environmental events and interpersonal factors on intrinsic motivation.     

A meta-analytic review of experiments examining the effects of extrinsic rewards on intrinsic motivation

A meta-analysis of 128 studies examined the effects of extrinsic rewards on intrinsic motivation. As predicted, engagement-contingent, completion-contingent, and performance-contingent rewards significantly undermined free-choice intrinsic motivation (d = -0.40, -0.36, and -0.28, respectively), as did all rewards, all tangible rewards, and all expected rewards. Engagement-contingent and completion-contingent rewards also significantly undermined self-reported interest (d = -0.15, and -0.17), as did all tangible rewards and all expected rewards. Positive feedback enhanced both free-choice behavior (d = 0.33) and self-reported interest (d = 0.31). Tangible rewards tended to be more detrimental for children than college students, and verbal rewards tended to be less enhancing for children than college students. The authors review 4 previous meta-analyses of this literature and detail how this study's methods, analyses, and results differed from the previous ones.     

Reward,affect, and young children's motivational orientation

In this study we examined the proposition that the detrimental effect of reward on young children's intrinsic motivation may be due to increased negative affect associated with performing the target task under expected reward conditions. Fifty-six children were randomly assigned to one of three non-reward mood induction conditions (positive, negative, neutral) or to a reward, neutral mood induction condition. Children then played an attractive game. Subsequent intrinsic interest was measured in a free-choice period in which rewards were neither forthcoming nor expected and children could freely choose to play with the target game or with other toys. It was found that rewards produced a less positive mood state, which subsequently was related to lowered intrinsic interest in the free-choice situation. In general, the results for the reward/neurtral mood condition paralleled those for the non-reward/negative mood condition. It was concluded that instrumental rewards may induce a temporary negative mood state in young children that can undermine intrinsic motivation.This research was sponsored in part by a Faculty-Grant-in-Aid (No. 420893) from Arizona State University, and by a Faculty Release Award from the Department of Family Resources and Human Development, both to the first author. The authors would like to express their appreciation to Barry Arbuckle, Anna Burke, Mia Nymoh, Darlene Richmond, Phil Swanson, and Irma Vega for their assistance in data collection.     

What happens during the free-choice period? Evidence of a polarizing effect of extrinsic rewards on intrinsic motivation

The “undermining effect” [e.g., Deci, E. L., Koestner, R., & Ryan, R. M. (1999) A meta-analytic review of experiments examining the effects of extrinsic rewards on intrinsic motivation, Psychological Bulletin, 125(6) 627–668], whereby extrinsic rewards decrease intrinsic motivation, is typically tested using the free-choice paradigm. The arbitrary length of the free-choice period, however, might obscure the process of undermining. We used a foreshortened free-choice period – immediately and after 1 week – to glimpse the process of undermining with 61 college students who engaged in an intrinsically interesting activity under a reward or no-reward condition. Analyses revealed a polarizing effect of extrinsic rewards on intrinsic motivation for the immediate and delayed assessments. We consider this effect in relation to the process of undermining, and suggest a potential personality-based moderator of the effect.     

Use of the maximal-operant principle to motivate children's intrinsic interest

The present research examined the hypothesis that in contrast to theory and research indicating that tangible reward decreases subsequent interest in enjoyable academic activities, rewards are perceived by adults as effective techniques to maximize long- and short-term subsequent interest for academic tasks of both high and low initial interest level. The results of our first three studies demonstrated that college students and parents view tangible reward as more effective than other less controlling techniques to enhance intrinsic motivation and value rewards more for intrinsically interesting academic behaviors in comparison with others (e.g., prosocial behaviors). Our fourth study supported the hypothesis that adults do not subscribe to the minimal-sufficiency analysis of increasing intrinsic motivation but prefer a maximal-operant principle in which the likelihood of producing long-term interest in academic tasks is assumed to vary positively with the size of a reward. Our fifth and sixth studies investigated illusory correlation as one mechanism that may perpetuate beliefs about the assumed positive relation between tangible reward and intrinsic interest in academic tasks.     

The effect of earlier experience and reward contingencies on intrinsic motivation

The effects of task-contingent and performance-contingent extrinsic rewards upon subsequent intrinsic motivation are compared. Intrinsic motivation is measured by behavioral observation in a free time period and by rating scales. The results show, as expected, a higher rating of intrinsic motivation in the performance-contingent reward condition. The study further compares strength of intrinsic motivation in one- and two-session conditions. As hypothesized, a two-session condition, in which the subjects have a preexperience with the task without reward administration, leads to a higher rating of intrinsic motivation than a one-session condition without such a preexperience. The behavioral measure of intrinsic motivation is not significantly affected by the conditions. A post hoc analysis of the data indicates that there may be a different effect of extrinsic rewards on behavioral measures and on rating scale measures of intrinsic motivation.     

A process analysis of the effects of performance-contingent rewards on intrinsic motivation

In this study, the effects of performance-contingent rewards on intrinsic motivation were examined in comparison to no-reward controls receiving identical performance feedback. A path analytic process analysis was conducted to examine the mediation of reward effects on subsequent task interest. It was hypothesized that competence valuation, or the personal importance of doing well, would be an important mediator of interest in situations where performance feedback was available. Rewards were predicted to affect interest by influencing an individual's valuation of competence, and by altering the competence valuation mediation process. In addition, achievement orientation was hypothesized to interact with reward in affecting importance and the mediation process. Prior to performing an interesting puzzle, high school students were offered a performance-contingent reward, and then indicated how personally important it was to do well. After doing three puzzles, all subjects received positive feedback regarding their performance. Multiple regression analyses indicated that importance was affected by the experimental variables, and had a positive causal impact on subsequent intrinsic motivation. It was found that the promise of performance-contingent reward positively affected importance for low achievers relative to high achievers, and that the mediation of subsequent intrinsic interest by importance differed according to reward by achievement combinations. Additionally, a direct effect revealed that performance-contingent rewards significantly enhanced interest, relative to no-reward controls receiving identical performance feedback.     

Competitively Contingent Rewards and Intrinsic Motivation: Can Losers Remain Motivated?

We explored the effects on intrinsic motivation and ego-involved persistence of winning versus losing a competitively contingent reward and, for losers, the additional effects of receiving either positive performance feedback or performance-contingent rewards. Winners were more intrinsically motivated than losers. Losers given an explicit normative standard who received positive feedback for meeting the standard were more intrinsically motivated than losers who did not receive the additional standard and feedback. Losers who received a performance-contingent reward for reaching the same explicit standard displayed less intrinsic motivation behaviorally assessed than did losers who got positive feedback, but the two groups did not differ on self-reported enjoyment. Effects on enjoyment were mediated by perceived competence, but effects on free-choice behavior were not. People who lost the competition showed more ego-involved persistence than people who won or did not compete.     

Does intrinsic reward motivate cognitive control? a naturalistic-fMRI study based on the synchronization theory of flow

Cognitive control is a framework for understanding the neuropsychological processes that underlie the successful completion of everyday tasks. Only recently has research in this area investigated motivational contributions to control allocation. An important gap in our understanding is the way in which intrinsic rewards associated with a task motivate the sustained allocation of control. To address this issue, we draw on flow theory, which predicts that a balance between task difficulty and individual ability results in the highest levels of intrinsic reward. In three behavioral and one functional magnetic resonance imaging studies, we used a naturalistic and open-source video game stimulus to show that changes in the balance between task difficulty and an individual’s ability to perform the task resulted in different levels of intrinsic reward, which is associated with different brain states. Specifically, psychophysiological interaction analyses show that high levels of intrinsic reward associated with a balance between task difficulty and individual ability are associated with increased functional connectivity between key structures within cognitive control and reward networks. By comparison, a mismatch between task difficulty and individual ability is associated with lower levels of intrinsic reward and corresponds to increased activity within the default mode network. These results suggest that intrinsic reward motivates cognitive control allocation.     

Immunizing children against the negative effects of reward: A further examination of intrinsic motivation training techniques

An investigation was conducted to extend previous research on the effect of intrinsic motivation focus sessions on children's subsequent motivational orientation and creativity in an expected‐reward situation. Numerous earlier studies have demonstrated the over justification effect: Initially interested in an activity, an individual who is led to engage in that activity in the presence of some salient extrinsic constraint will judge him‐ or herself to be motivated by the constraint and not by his own interest. This phenomenon has been demonstrated across the life span. Even very young children who work on an interesting task in order to obtain a reward evidence lower subsequent intrinsic motivation than do children not working for a reward. Other research has shown similar negative effects on creativity. However, two recent investigations indicated that the usual over justification effect need not always occur. These studies demonstrated that the undermining of school children's intrinsic motivation and creativity may be counteracted by means of videotaped modeling and directed discussion sessions that explicitly (a) deal with ways to cognitively distance oneself from reward contingencies and (b) focus on intrinsic reasons for working in school. The present study incorporates important refinements of these earlier immunization attempts and provides particularly strong evidence for the hypothesis that children participating in sessions designed to focus on intrinsic reasons for doing things in school will later treat reward as an actual augmentation of intrinsic motivation. Theoretical and practical implications of this phenomenon are discussed.     

Extrinsic and intrinsic motivation at 30: Unresolved scientific issues

The undermining effect of extrinsic reward on intrinsic motivation remains unproven. The key unresolved issues are construct invalidity (all four definitions are unproved and two are illogical); measurement unreliability (the free-choice measure requires unreliable, subjective judgments to infer intrinsic motivation); inadequate experimental controls (negative affect and novelty, not cognitive evaluation, may explain "undermining" effects); and biased metareviews (studies with possible floor effects excluded, but those with possible ceiling effects included). Perhaps the greatest error with the undermining theory, however, is that it does not adequately recognize the multifaceted nature of intrinsic motivation (Reiss, 2004a). Advice to limit the use of applied behavior analysis based on "hidden" undermining effects is ideologically inspired and is unsupported by credible scientific evidence.     

Identifying the neural substrates of intrinsic motivation during task performance

Intrinsic motivation is the inherent tendency to seek out novelty and challenge, to explore and investigate, and to stretch and extend one’s capacities. When people imagine performing intrinsically motivating tasks, they show heightened anterior insular cortex (AIC) activity. To fully explain the neural system of intrinsic motivation, however, requires assessing neural activity while people actually perform intrinsically motivating tasks (i.e., while answering curiosity-inducing questions or solving competence-enabling anagrams). Using event-related functional magnetic resonance imaging, we found that the neural system of intrinsic motivation involves not only AIC activity, but also striatum activity and, further, AIC–striatum functional interactions. These findings suggest that subjective feelings of intrinsic satisfaction (associated with AIC activations), reward processing (associated with striatum activations), and their interactions underlie the actual experience of intrinsic motivation. These neural findings are consistent with the conceptualization of intrinsic motivation as the pursuit and satisfaction of subjective feelings (interest and enjoyment) as intrinsic rewards.     

The differential effects of tangible rewards and praise on intrinsic motivation: A comparison of cognitive evaluation theory and operant theory

Substantial research indicates that tangible rewards, such as money, prizes, and tokens, decrease response rates by undermining intrinsic motivation. In contrast, praise appears to increase response rates by enhancing intrinsic motivation. Based on their interpretation of available evidence, many social-cognitive researchers warn not to use tangible rewards in applied settings and to use praise instead. Furthermore, they suggest that the differential effects of the two types of rewards on intrinsic motivation cannot be explained using principles of operant psychology. Cognitive evaluation theory provides one of the most recent and widely cited social-cognitive explanations for the different effects of the two types of rewards on intrinsic motivation (Deci & Ryan, 1985). However, a review of existing research found little support for the explanations based on this theory and revealed three potential confounding effects: (a) temporal contiguity, (b) the number of reward administrations, and (c) discriminative stimuli associated with reward availability. These three confounding factors provide explanations for the effects of tangible rewards and praise on intrinsic motivation that are consistent with principles of operant psychology.     

Increases in rewards promote flexible behavior

Offering reward for performance can motivate people to perform a task better, but better preparation for one task usually means decreased flexibility to perform different tasks. In six experiments in which reward varied between low and high levels, we found that reward can encourage people to prepare more flexibly for different tasks, but only as it increased from the level on the previous trial. When the same high rewards were offered continuously trial after trial, people were more inclined to simply stick with doing what had worked previously. We demonstrated such enhancements in flexibility in task switching, a difficult visual search task, and an easier priming of pop-out search task, which shows that this effect generalizes from executive tasks to perceptual processes that require relatively little executive control. These findings suggest that relative, transient changes in reward can exert more potent effects on behavioral flexibility than can the absolute amount of reward, whether it consists of money or points in a social competition.     

Motivational synchronicity: Priming motivational orientations with observations of others’ behaviors

Two experiments tested the motivational synchronicity hypothesis, according to which observation of a target person’s behavior implying an intrinsic or an extrinsic motivational orientation primes the observers’ corresponding motivational orientation. Experiment 1 revealed that participants exposed to a target person intrinsically motivated to perform a task, relative to those exposed to an extrinsically motivated target person, showed greater intrinsic motivation (free-choice persistence) for the same task. Experiment 2 extended this in two important ways: (1) different tasks were used for the target and participant in order to rule out an expectation-based interpretation of the results, and (2) performance on an activity known to be facilitated by intrinsic motivation was used as the dependent measure. It appears that simply observing others’ motivational orientations influences the accessibility of the observers’ corresponding motivational orientation.     

Exploring the Effects of Ostracism on Performance and Intrinsic Motivation

Two experiments investigated the effects of ostracism on performance and intrinsic motivation. Participants were either included or ostracized via an online ball-tossing game and then completed two trials of an interesting word-search task. Later, they engaged in a free-choice trial designed to assess their intrinsic motivation for the word-search task. Results indicated that ostracized participants performed more poorly and experienced lower positive mood and relatedness than included participants. Although no direct effects of ostracism on intrinsic motivation were found, in both studies ostracism indirectly affected intrinsic motivation through positive mood, such that ostracism led to poorer mood and, in turn, lower intrinsic motivation. Implications for future research on ostracism in organizations are discussed.     

The effects of choice on intrinsic motivation and related outcomes: a meta-analysis of research findings

A meta-analysis of 41 studies examined the effect of choice on intrinsic motivation and related outcomes in a variety of settings with both child and adult samples. Results indicated that providing choice enhanced intrinsic motivation, effort, task performance, and perceived competence, among other outcomes. Moderator tests revealed the effect of choice on intrinsic motivation was stronger (a) for instructionally irrelevant choices compared to choices made between activities, versions of a task, rewards, and instructionally relevant options, (b) when 2 to 4 successive choices were given, (c) when rewards were not given after the choice manipulation, (d) when participants given choice were compared to the most controlling forms of control groups, (e) for children compared to adults, (f) for designs that yoked choice and control conditions compared to matched designs in which choice was reduced or designs in which nonyoked, nonmatched controls were used, and (g) when the experiment was conducted in a laboratory embedded in a natural setting. Implications for future research and applications to real-world settings are discussed.     

On how task-contingent rewards,individual differences in causality orientations,and imagery abilities are related to intrinsic motivation and performance

This study explored how causality orientations, individual differences in imagery, and reward contingency are related to performance and intrinsic motivation. Cognitive evaluation theory, as applied to both causality orientation and reward contingency, was used to make predictions about the effects of internal or external events perceived as being autonomy supportive or controlling. In the light of the fact that task-contingent rewards must be salient to undermine intrinsic motivation and performance, one can suppose that high imagery may increase the controlling aspects of task-contingent rewards. Moreover, research now indicates that vegetative activation correlates with levels of imagined effort, and that high imagery capabilities enhance performance in motor skills. The main purpose of this study was to contribute some arguments for imagery and reward interaction effects on intrinsic motivation and performance. As predicted, autonomy-oriented subjects reported more interest and intrinsic motivation, and exhibited better performance than did control-oriented individuals. Similar differences were observed in favour of high-imagery individuals. Moreover, the effects of imagery were not only subject to an interaction between imagery and causality orientation, but also between imagery and reward contingency. The links between these variables are discussed in the framework of both Carver and Scheier's (1981) motivational control theory, and Deci and Ryan's (1985a) cognitive evaluation theory. © 1998 John Wiley & Sons, Ltd.