* SENSITIVITY TO REWARD IN CHILDREN WITH ADHD: IMPLICATIONS FOR BEHAVIORAL MANAGEMENT
Among the different ideas that have been proposed for factors contributing to the symptoms of ADHD, abnormal responsivity to behavioral rewards has a long history. Some researchers have suggested that children with ADHD have a reduced sensitivity to reward, which requires that they be rewarded more often to maintain good behavior. Others suggest that they actually have a heightened sensitivity to reward - specifically that they show an increased tendency to seek immediate rewards. As a result, they become more easily distracted and pulled off tasks that require long-term effort before any reward is obtained.
In this interesting experimental study the authors tried to test these competing ideas about sensitivity to reward in children with ADHD (Tripp, G., & Alsop, B. (1999). Sensitivity to reward frequency in boys with ADHD. Journal of Clinical Child Psychology, 28, 366-375.) This is very much a laboratory-type experiment rather than a more "real world" type study, but is one that seems to have important applications for the day to day management of children with ADHD.
Fifteen boys with ADHD and 15 matched control children with an average age of 10 served as participants. All the ADHD children were probably of the Combined Type - i.e. they had both inattentive and hyperactive/impulsive symptoms. As in many studies of ADHD, girls were unfortunately not included.
The task for participants in the study was to sit in front of a computer screen on which either of 2 highly similar stimuli were repeatedly displayed for a very brief instant. After each presentation, children were required to press a button to indicate which stimulus they had seen. Correct responses were signaled by the computer and children knew that they would be awarded points that they could later use to purchase a desirable prize.
Not every correct response was rewarded, however. Instead, the computer was programmed so that a correct response for one of the two stimuli would be rewarded 3 times as often as the other. Thus, during the task, the children learned that a correct response for one of the stimuli was more likely to produce a reward than a correct response for the other.
Because of this differential rate of reward for correct identifications of the 2 stimuli, a bias developed to select the stimuli that was most likely to be rewarded. This simply means that children developed a tendency to select the more- frequently rewarded stimulus more often, even though the two were presented an equal number of times.
What was interesting, however, is that for children with and without ADHD, the strength of this bias was found to depend heavily on which stimulus had been most recently rewarded. Consider the situation in which the child was just rewarded for correctly identifying the stimulus that had been consistently rewarded more often throughout the test session. In this scenario, children with and without ADHD showed a similar tendency to select this stimulus on the next trial, even if this was the incorrect choice.
What about when the most-recently rewarded choice was for the stimulus that had been rewarded less often? For children without ADHD, the "bias" they displayed on the very next trial was still heavily in favor of the more-frequently rewarded stimulus. In other words, they did allow their most-recently rewarded choice to alter what they had learned was more likely to be the "best bet". For children with ADHD, however, the results were quite different and the strong bias in favor of the more consistently rewarded choice disappeared on the next trial. In other words, the behavior of the children with ADHD was influenced less by their overall experience of reward on the task and more by the very last reward that they had obtained. What's more, this same tendency was evident - although to a slightly lesser degree - even when the children with ADHD were tested while on medication.
What are the implications of these results for understanding the day-to-day, moment-to-moment behavior of children with ADHD? To me, it seems that these results underscore the extent to which children with ADHD live much more "in the moment" than do other children. As demonstrated in this experiment, their behavior is much more likely to be influenced by their most recent experience with being "rewarded", even when this recently rewarded behavior is inconsistent with a more long-standing learning history. Thus, when a behavior meets with some success (i.e. it results in obtaining some type of desired response) they may tend to forget that this is not what has typically occurred before and back away from behaviors that have been more consistently rewarded.
It is not difficult to imagine how this could play itself out in "real life". Based on these findings, a parent could be doing a really excellent job of consistently praising and rewarding behaviors that they are working to promote in their child and ignoring or even punishing a particular unwanted behavior like whining. As a result, their child is learning that the desired behaviors are more likely to result in the kinds of social and even tangible outcomes they desire, and begin to display this behavior with greater frequency.
Consistently standing firm in response to a child's whining is difficulty for anyone, however, and there are bound to be instances when a parent "gives in" to their child's demands in an attempt to obtain some quick relief and needed peace. Unfortunately, as the data from this study indicate, the result for many children with ADHD is that when this whining behavior has been "rewarded" by the parent's giving in, it becomes increasingly likely that they will engage in this behavior again soon.
In other words, unlike other children who would be more likely to recognize that this was an isolated and unlikely-to-be-repeated event (i.e. based on the history of what has been rewarded in the past), the child with ADHD may tend to disregard the history and base their next "behavioral choice" on what has been most recently successful. Unfortunately, this "choice" may often reflect behavior you are trying to discourage that has been inadvertently rewarded.
This "heightened sensitivity" to the most-recently rewarded behavior underscores the important need for consistency in behavioral interventions designed for a child with ADHD. It also helps in understanding why behavioral interventions for a child with ADHD can be, at times, so difficult and frustrating to implement effectively.
On the positive side, the sensitivity that children with ADHD show to recently rewarded behavior suggests it may be possible to alter long-standing patterns of negative behavior by being consistent and vigilant about rewarding the new types of behavior you are trying to promote. You just have to be really careful to reward the new behavior consistently, and do your best to avoid the "slip ups" noted above.
In my experience, and corroborated in a variety of studies on this topic, it can be difficult for parents to do this when they are under undue stress themselves, and when they do not have the necessary supports in place to help in following through on a well -designed behavioral treatment plan. This is where consulting with an experienced child mental health professional, and enlisting the support of other parents struggling with similar issues, can be so helpful. This is hard work, but can make a substantial difference in children's ability to be successful both at home and at school.
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Dept. of Psychology
University of Otago
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A note from Dr. Rabiner:
I hope the above information was of interest to you and potentially helpful. Staying informed about the latest research findings on ADD/ADHD will enable you to make better informed decisions about the best ways to promote your child's healthy development. That is my objective in publishing a monthly newsletter, ADHD RESEARCH UPDATE, and I invite you to become a regular subscriber. If you work with children who have ADHD in a professional capacity, I also think you will find that ADHD RESEARCH UPDATE is a convenient way to stay on top of important new research information.
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David Rabiner, PhD
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