A NEW THEORY OF ADHD Russell A. Barkley, Ph.D. The current clinical consensus holds that ADHD is comprised of three primary symptoms: inattention, impulsivity, and hyperactivity. Inattention is often stressed as a primary feature of the disorder. Yet research on ADHD often finds that inattention is not reliably found in children with ADHD or does not distinguish the condition from other psychopathological disorders. This is not to say that those with ADHD are not observed to be ``off-task'' more, lower in persistence of effort, and less able to continue responding to assigned work--they surely are. It is to say that formal laboratory measures of various components of attention do not reliably find the problems of those with ADHD to be in the realm of attention. Instead, the most consistent findings show a primary deficit in behavioral or response inhibition, the ability to delay responses, or the tolerance for delay intervals within tasks. Thus, the primary component of ADHD is more one of disinhibition or poor delay of response than inattention. Most investigators working in the area of ADHD with whom I have spoken seem to agree with this assessment of the extant literature and its conclusions. Assuming for now that poor response inhibition or inability to delay response is the major hallmark of ADHD, how does this explain the myriad problems those with ADHD encounter in their academic, social, familial, emotional, occupational, and other domains of adaptive functioning? Why is such a deficit so debilitating to the successful adaptive performance of the individual in meeting the demands of daily social life? And how would this explain the poor organization and planning, poor sense of time management, deficits in mental arithmetic computation, delayed self-directed speech, immature social communication with peers, heightened emotionality, diminished problem-solving ability, limited sense of self-awareness, and delayed moral development, to name but a few of the deficits noted in ADHD children? I believe that an answer may rest within a theory proposed by Jacob Bronowski (1967/1977) over 25 years ago concerning the evolution of human language from other forms of primate social communication that led to several unique features of human language and cognitive abilities. [Bronowski was a distinguished mathematician, physicist, philosopher, and science writer most widely known for his book, The Ascent of Man, and the public television show based on this work in the late 1970s. Like any new and useful theory, this one should better explain the findings in the literature on ADHD, accounting for findings not easily explained by existing theoretical models, such as those stressing attention. Moreover, it should direct our research and clinical attention to new areas worthy of exploration not previously thought relevant to ADHD. I believe that my extrapolation of Bronowski's theory to ADHD meets these requirements and provides a deeper understanding of the difficul- ties faced by those with ADHD in meeting the demands of daily adaptive functioning. It also seems to suggest that the impact of ADHD on daily living may be more pervasive than was once believed. BRONOWSKI'S THEORY OF DELAYED RESPONDING AND LANGUAGE Bronowski cogently argued that a major advancement in the evolution of human communication arose initially as an increase in the simple capacity to delay responses to a signal, message, or event. The human capacity to delay responding vastly exceeds that of our nearest primate relatives by a quantum leap. This capacity to inhibit initial reactions to events, arising primarily from the expansion of the frontal lobes, permitted the later development of four uniquely human mental abilities: separation of affect, prolongation, internalization, and reconstitution. If ADHD represents a relative deficit in the development of delayed responding or response inhibition in the individual, as I believe, then these four mental processes should also be less proficient and less likely to guide or inform ongoing adaptive behavior than in those not deficient. The evidence that they are is quite compelling. Separation of Affect. Bronowski argued that the delay in human responding permits the referral of the incoming signal, message, or event to more than one brain system at a time, allowing simultaneous processing of the event by multiple reference centers--the primary advantage of a large brain, he proposed. In so doing, humans are able to split the signal separately into its affective charge and its information or content. This capacity to separate feeling from fact, affect from content, and form from substance, permits humans to deal with the content of the message alone. All other species respond to these two features of a signal or message immediately and in total. Affect and content are one in the signal and in the response to it. In humans, the response delay permits the splitting of both the signal and the response to it into the separate features of content and affective charge. The ability to separate affect from informational content in signals and response permits humans the power of objectivity, perspective, logic, and rationality, as we ordinarily think of these attributes. It also ultimately underlies the human capacity for conducting science. If those with ADHD are less able to delay or inhibit responses to momentary signals or events, we should find them less able to utilize this downstream capacity for the separation of affect and thus less likely to have it inform and guide their ongoing adaptive behavior. They should react more often to the affective charge of a message or event than do others, and respond with greater intensity and range of affect as well. In short, they should prove more emotionally reactive to social situations than those without ADHD. They should also prove less objective in their assessment of the situation, more self-centered (less perspicacious), and less ``scientific'' or logical in their reactions to social situations, particularly those imbued with more affective signals than usual. I and many others have been struck by just these social limitations in the behavior of those with ADHD seen in clinical situations. Yet minimal research exists on the issue. Prolongation. Bronowski reasoned that response delay also permits the signal to be more strongly and symbolically fixed mentally (working memory) through language and imagery. This has the effect of sustaining the mental existence of the stimulus during the delay long after the external event has passed into nonexistence in real time. This symbolic fixing of the signal permits time to refer or compare it with memory of other such events from which emerges our sense of past or hindsight. From this referencing backward in time and the manipulation of our recall of these past events in working memory derive our imagination and our sense of the future. The latter likely arises from our use of past events in memory to conjecture hypothetical futures. The consideration of such hypothetical futures leads to the formation of plans that propose action at a future time. Through our communication with others we can then exchange such proposals or messages for future action--an ability seen in no other species. To summarize, the delay in responding permits a stronger, more lasting mental fixing of the signal from which springs hindsight, imagination, fore-thought, and our general sense of time--capacities apparently unique to our species. Again, my extension of this theory to ADHD would indicate that those with the disorder should be less proficient in the utilization of these capacities in view of their inability to delay responding. Failing to delay precludes the adequate usage of these mental abilities to glean information than can inform or guide ongoing adaptive behavior. After all, what is the point of using such capacities if the response to the signal or event is already released? It is too little, too late to guide adaptive behavior. If true, my application of this theory to ADHD points to a diminished sense of, or window on, time and its utilization in guiding behavior, a diminished sense of hindsight and forethought and their governance of current behavior, and a diminished capacity in those with ADHD to fix signals in working memory. Could these deficiencies explain why those with ADHD show less learning from past experience (hindsight), greater forgetfulness (fixing of the signal), less concern for future events, and a diminished sense of time in the guidance of ongoing adaptive behavior? Might it also explain the diminished capacity for performing mental calculations? I know of no research on these issues yet am impressed with how often I find such problems in the clinical presentation of my cases and how responsive ADHD adults are to my inquiring about them. Internalization. Bronowski theorized that the imposition of a delay between signal and response permits humans to use language not only as a form of communication with others, as it is used by other species, but as a means of communicating with oneself. In this process language is turned on the self and eventually internalized, permitting us the powers of reflection, rule formation, and the governance of behavior by such rules (plans, propositions for action) and, more generally, self-control. This capacity for rule creation and rule-guided behavior, as Steve Hayes (1989) argued, frees humans up from the control of behavior by the moment (contingency-shaped behavior) or immediate context, and brings their behavior under the control of language, rules, plans or proposals for action. In so doing, behavior becomes less variable, less subject to control by spurious or superstitious momentary consequences, more future oriented, less emotional (due to less exposure to contingency-shaping that results in more emotional reactions), and better suited to mediating long delays in schedules of consequences (deferred gratification). We can exchange these rules with others, providing the foundation for the transmission of culture (morals, mores, norms, policies, laws, and the wisdom acquired from past generations) to new generations. Applying Bronowski's theory to those with ADHD suggests that their inability to delay responding should result in less mature self-directed speech, diminished reliance on internalized language to control behavior, less utilization of reflection, diminished control of behavior by proposals for action (rules and instructions), especially in reference to a future time, and poorer self-control in general. That moral development would be more delayed in those with ADHD is an obvious consequence as well. Behavior in those with ADHD should be more variable, more controlled by momentary context, more emotional and contingency-shaped, less directed to future consequences, and less able to mediate delays between responding and later consequences. Again, this seems to fit with research findings on self-directed speech, rule governance, and moral development in children with ADHD, and squares beautifully with what I see clinically as well. Reconstitution. Finally, Bronowski proposed that from the delay in responding and the internalization of language it permits we derive the abilities of analysis and synthesis. That is, we can deconstruct events and signals into parts, progressively redistributing them into particulars (objects, properties, actions) and progressively generalize their hortative content (proposals for action). We can then reassemble these particulars into entirely new outgoing messages. This not only underlies our dramatically superior powers of generative language but also of analysis and creativity (synthesis)--powers vastly expanded through this process of reconstitution. My generalization of this model to ADHD instructs us to consider whether those with ADHD are lessable to utilize these capacities in daily ongoing adaptive behavior than others. Are they less analytical, less capable of problem-solving on demand, and less given to synthesis or less creativity in coping with daily events? I am not sure, and minimal research exists on the issue. It seems highly worth a look. CONCLUSION My adaptation of Bronowski's theory of delayed responding to ADHD, in which an impairment in inhibition likely exists, seems to provide a more elegant explanation of existing research findings, a deeper appreciation for the pervasive impact of the disorder on daily life, and exciting suggestions for numerous future research explorations. Mind you, it is not that those with ADHD are incapable of separation of affect, prolongation, internalization, and reconstitution, but that the inability to delay response results in less utilization of, and reliance upon, these downstream mental abilities in informing and guiding ongoing responses. Improve the capacity for delay and these downstream mental functions should act more proficiently, providing forward information to guide ongoing adaptive behavior. Evidence from recent studies (Berk & Potts, 1991) on stimulant medication suggests just such an improvement in these mental abilities when inhibition is increased by medication. And so it is not that those with ADHD do not think before they act so much as they act before permitting time to think. Rabelais was right: ``Everything comes to those who can wait.'' REFERENCES Berk, L. E., & Potts, M. K. (1991). Development and functional significance of private speech among attention-deficit hyperactivity disorder and normal boys. Journals of Abnormal Child Psychology, 19, , 357-377. Bronowski, J. (1967). Human and animal languages. To honor Roman Jakobson (Vol. 1). The Hague, Netherlands: Mouton & Co. Bronowski, J. (1977). Human and animal languages. A sense of the future (pp. 104-131). Cambridge, MA: MIT Press. Hayes, S. (1989). Rule-governed behavior. New York: Plenum.