J. Child Psyihoi Psychiat. Vol. 33, No. 2, pp. 387-398, 1992 Printed in Great Britain.

0021-9630/92 J5.00 + 0.00 Pergamotl Press pic © 1992 Association for Child Psychology and Psychiatry

Hyperactivity and Delay Aversion—I. The Effect of Delay on Choice E. J. S. Sonuga-Barke, E. Taylor, S. Sembi and J. Smith Abstract—Two experiments are reported in which hyperactive and control children repeatedly chose between small immediate and large delayed rewards. In experiment 1, the best choice option was manipulated by varying levels of delay after reward delivery. In experiment 2 it was manipulated by changing the economic constraint (10 minutes or 20 trials). Both groups were equally efficient at earning points under most conditions, but hyperactive children exhibited a maladaptive preference for the small reward under the trials constraint. The results suggest that hyperactive children were more concerned to reduce overall delay levels than either to maximize reward amount or immediacy. Keywords: Hyperactivity, functional analysis, choice, impulsiveness

Introduction Recent analyses of the problems of hyperactivity have emphasized the impulsiveness that such children show (Sergeant, 1989; Douglas, 1989). It has been argued for a long time that the most fundamental deficit of hyperactive children is a failure to 'stop, look and listen' (Douglas, 1972). In line with this, impulsive behaviour has become part of most modern definitions—especially in the sense of over-rapid responses in situations of uncertainty (Sergeant, 1989). There is now a large volume of test evidence to support the idea that hyperactive children are impulsive. On the Matching Familiar Figures Test (MFFT; Kagan, 1965) children have to identify a target figure from amongst a series of similar distractor figures. Hyperactive children choose more quickly than controls and consequently make more mistakes (DeHaas, 1986; DeHass & Young, 1984; Juliano, 1974; Rosenbaum & Baker, 1984). On schedules of differential reinforcement of long duration (DRL) a reinforcer becomes available only after a predetermined length of time. Hyperactive children respond before that time is up more often than controls and so gain less reinforcement (Gordon, 1979; McClure & Gordon, 1984). In the Delay of Gratification Paradigm (DGP: Mischel, 1974) children have to make a choice Accepted manuscript received 6 February 1991

Department of Child and Adolescent Psychiatry, Institute of Psychiatry, University of London, U.K. Requests for reprints to: Edmund Sonuga-Barke, Department of Psychology, University of Southampton, Southampton, U.K.

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between an immediately available small (less valued) reward and a large (more valued) reward that is available only after an extended period of delay. Rapport, Tucker, DuPaul, Merlo and Stoner (1986) have found that hyperactive children take the smaller reward by terminating the waiting period more often than controls. Each of these fmdings in their way has been seen as confirming that hyperactive children are impulsive. Most accounts of childhood behavioural deviance have been based on an assumption of dysfunction. From this perspective it is assumed that hyperactive children's apparent impulsiveness is the result of a more or less specific deficit in regulative functioning (cf. Douglas & Peters, 1979) or inhibitory processes (Quay, 1988). For instance, when hyperactive children press the button too soon and so forfeit rewards on the DRL task, or choose the small immediate reward over the large reward on the DGP, it is assumed that this apparent 'impulsiveness' is due to an inability to withhold inappropriate responses (Schachar & Logan, 1990) or to wait for future rewards. The regulative/inhibitory deficit hypothesis argues that hyperactive children don't wait, not because they don't want to wait but because they can't wait. A second, and more novel approach, to understanding this style of behaviour is to assume that it is an adaptive response to a particular situation. According to this view, it serves to maximize (or minimize) some aspect of that situation and provides a means to particular economic ends. Broadly speaking this approach might be described as behavioural economics (cf. Rachlin, 1980; Sonuga-Barke, 1989). The behavioural economic approach to hyperactivity emphasizes the need for a functional analysis of impulsiveness concentrating on the economic significance of this style of behaviour. A characteristic common to each of the expressions of apparent impulsiveness described above is a pronounced sensitivity to the passage of time required before a valued reward can be obtained. Hyperactive children seem to be unusually sensitive to differences in pre-reward delay and choose the more immediate alternative (whether that alternative is rewarding or not) over a rewarding delayed alternative. In the case of DRL and DGP these rewards are often material (money or prizes); in the case of the MFFT they are social (praise and encouragement). We suggest that this sensitivity to differences in pre-reward delay could be the product of one of three motivational attitudes. In the terms of this paper, choice of an immediate alternative might serve three economic functions. 1. It maximizes reward immediacy and minimizes pre-reward delay. Hyperactive children' s choices may be motivated solely by a desire to minimize levels of pre-reward delay. If this is the case they will be sensitive exclusively to differences in pre-reward delay and choose the most immediate reward irrespective of other economic constraints and reward conditions. As it is difficult to distingfuish any expression of this sensitivity to pre-reward delay from an inhibitory or regulative deficit it can appropriately be called true impulsiveness. 2. It maximizes the number of rewards that can be won during testing. In many situations manipulations of pre-reward delay are confounded with that of reward density (Navarick, 1986). For instance, in the DGP a choice of a small immediate reward might also be associated with the chance to earn more rewards per unit of time.

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The 'large' reward might in the long run be less valuable. In the MFFT a fast and inaccurate strategy might lead to a larger number of correct responses per time period than a slower more reflective approach. In both these situations the alternative offering the higher reward density also offers the better reward earning strategy so that a response style that is seen as evidence of impulsiveness can also be a rational choice as it leads to more rewards overjill. Given all this it may be that hyperactive children are rational in their choices and choose the immediate alternative because it is associated with a higher density of rewards and so more reward overall. Hyperactive children may only be sensitive to differences in pre-reward delay levels when these are related to the number of rewards that can be won. They will choose the alternative offering the best reward earning strategy irrespective of economic constraints and reward conditions. Navarick (1986) has suggested that it is inappropriate to call this impulsiveness because the sensitivity to delay is not maladaptive. To distinguish it from impulsiveness then we will call it reward maximization.

3. It minimizes overall levels of delay. A third alternative is that hyperactive children are equally sensitive to delay occurring both before and after reward delivery (preaw

Hyperactivity and delay aversion--I. The effect of delay on choice.

Two experiments are reported in which hyperactive and control children repeatedly chose between small immediate and large delayed rewards. In experime...
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