JURNAL TRAINING ATTENTION, SELECTIVE ATTENTION, SUSTAINED ATTENTION AND ADHD

171 Pages·2017·9.75 MB·English

JURNAL

TRAINING ATTENTION, SELECTIVE ATTENTION,
SUSTAINED ATTENTION AND ADHD

Diunduh oleh:

NURDIANI
1371040010

FAKULTAS PSIKOLOGI
UNIVERSITAS NEGERI MAKASSAR
MAKASSAR
2018
DAFTAR ISI
No. Judul NamaPenulis Penerbit Tahun
Terbit
1 Behavioral inhibition, - Barkley, R. A Psychological 1997
sustained attention, and Bulletin,
executive functions
constructing a unifying
theory of adhd.
2 Larger deficits in brain - Booth, J. R Child Psychology 2005
networks for response - Burman, D. D and Psychiatry
inhibition than for - Meyer, J. R
selective attention in - Lei, Z
attention deficit - Trommer, B. L
hyperactivity disorder - Davenport, N. D
(ADHD). - Li, W.
- Parrish, T. B.
-Gitelman, D. R.
-Mesulam, M. M
3 Components of - Clikeman, M. S Epilepsia
attention in children - Wical, B. 1999
with complex partial
seizures with and
without ADHD.
4 Sustained attention in - Finneran, D. A. Speech, language, 2009
children with specific - Francis, A. L. and Hearing
language impairment - Leonard, L. B Research
(SLI).
5 Sustained and selective - Hooks, K. Clinical Child 1994
attention boys with - Milich, R. Psychology
attention deficit - Lorch, E. P.
hyperactivity disorder.
6 Investigation of a direct - Kerns, K. A. Developmental 1999
intervention for - Eso, K. Neuropsychology
improving attention in - Thomson, J.
young children with
adhd.
7 The cognitive - Sarter, M. Brain Research 2001
neuroscience of - Givens, B. Reviews
sustained attention: - Bruno, J. P.
Where top-down meets
bottom-up.
8 Efectiveness of - Sohlberg, M. M. Clinical and 1987
attention-training - Mateer, C. A. Experimental
program. Neuropsychology,
9 A measure of children's - Weber, A. M. Developmental 1990
attentional capacity. - Segalowitz, S. J. Neuropsychology,
10 Treating attention in - Murray, L. L. Journal of 2006
mild aphasia: - Keeton, R. J. Communication
Evaluation of attention - Karcher, L. Disorders
process training-II.
Psychological Bulletin Copyright 1997 by the American Psychological Association, Inc.
1997, Vol. 121, No, ,1 65-94 0033-2909/97/$3.00
Behavioral Inhibition, Sustained Attention, dna Executive "snoitcnuF
Constructing a Unifying Theory of ADHD
Russell A. Barkley
University of Massachusetts Medical Center
Attention deficit hyperactivity disorder (ADHD) comprises a deficit in behavioral inhibition. A
laciteroeht model is constructed that links inhibition ot 4 executive neuropsychological functions
that appear to depend on it for their effective execution: (a) working memory, (b) self-regulation
of affect-motivation- arousal, (c) internalization of ,hceeps dna (d) reconstitution (behavioral analy-
sis dna synthesis). Extended to ADHD, eht model predicts that ADHD should be associated with
yradnoces impairments in these 4 executive abilities dna eht motor control they afford. ehT author
reviews evidence for each of these domains of functioning dna finds it ot be strongest for sticifed
in behavioral inhibition, working ,yromem regulation of motivation, dna motor control in those with
.DHDA Although eht model is promising sa a potential theory of self-control and ADHD, far more
hcraeser is required to evaluate its merits and eht many predictions it makes about .DHDA
For over 20 years, attention deficit hyperactivity disorder Klein & Mannuzza, 1991; Weiss & Hechtman, 1993). Over
(ADHD) has been viewed as comprising three primary symp- development, ADHD is associated with greater risks for low
toms, these being poor sustained attention, impulsiveness, and academic achievement, poor school performance, retention in
hyperactivity (American Psychiatric Association APA, 1980, grade, school suspensions and expulsions, poor peer and family
1987; Barkley, 1981; Douglas, 1972, 1983). These behavioral relations, anxiety and depression, aggression, conduct problems
deficits arise relatively early in childhood, typically before the and delinquency, early substance experimentation and abuse,
age of 7, and are fairly persistent over development (Barkley, driving accidents and speeding violations, as well as difficulties
1990; Hinshaw, 1994; Weiss & Hechtman, 1993). The three in adult social relationships, marriage, and employment (Bark-
major impairments now have been reduced to two, with hyperac- ley, 1990; Barkley, Fischer, et al., 1990; Barkley, Guevremont,
tivity and impulsivity constituting a single impairment. As a Anastopoulos, DuPaul, & Shelton, 1993; Barkley, Murphy, &
result, three subtypes of the disorder have been proposed in the Kwasnik, 1996, in press; Biederman, Faraone, & Lapey, 1992;
current clinical view of ADHD offered in the fourth edition Hinshaw, 1994; Murphy & Barkley, in press; Nadeau, 1995;
of the Diagnostic and Statistical Manual of Mental Disorders Weiss & Hechtman, 1993). Most of these developmental risks
(DSM-IE," APA, 1994): predominantly inattentive, predomi- may be exacerbated by the presence of comorbid aggression-
nantly hyperactive-impulsive, and combined types. conduct problems (Barkley, Fischer, et al., 1990; Barkley et al.,
ADHD occurs in approximately 3-7% of the childhood popu- 1993; Hinshaw, 1987, 1992, 1994). Treatments for ADHD often
lation (Barkley, 1990; Szatmari, 1992), with boys being over- include parent, family, and teacher counseling about the disor-
represented, on average, approximately 3:1. The disorder per- der; parent and teacher training in behavior management tech-
sists into adolescence in 50-80% of cases clinically diagnosed niques; special education resources; and psychoactive medica-
in childhood and into adulthood in 30-50% or more of these tions (Barkley, 1990).
same cases (Barkley, Fischer, Edelbrock, & Smallish, 1990; The history of ADHD has been reviewed elsewhere (Barkley,
1990; Schachar, 1986; Werry, 1992), so I only briefly consider
it here. Initially, the symptoms were thought to arise out of poor
volitional inhibition and defective moral regulation of behavior
Russell .A ,yelkraB stnemtrapeD of yrtaihcysP and ,ygolorueN -revinU (Still, 1902). Later, problems with hyperactivity were thought
sity of sttesuhcassaM Medical .retneC to be the major feature of the disorder (Chess, 1960; Laufer &
This article saw supported by Grants MH45714, MH42181, dna Denhoff, 1957). Eventually, Douglas (1972; Douglas & Peters,
38514HM from eht National Institute of Mental Health and Grant
1979) stressed an equal if not greater role for poor sustained
17182DH from eht National Institute of Child Health dna Human
attention and impulse control in the disorder. She subsequently
.tnempoleveD
amended her view to include four major deficits: (a) poor invest-
I thank Charles Cunningham, Eric Mash, and Steve Hayes for their
ment and maintenance of effort, (b) deficient modulation of
enlightening discussions of this theoretical model and their snoitseggus
arousal to meet situational demands, (c) a strong inclination to
for its .tnemevorpmi
Correspondence concerning this article should be addressed ot seek immediate reinforcement, along with (d) the originally
Russell .A ,yelkraB Department of ,yrtaihcysP University of -uhcassaM proposed difficulties with impulse control (Douglas, 1980,
setts Medical Center, 55 Lake Avenue North, ,retsecroW Massachu- 1983). Douglas (1988) later concluded that these four defi-
setts 01655. Electronic mail yam be sent via Internet ot @yelkrabr ciencies arise from a more central impairment in self-regulation
bangate 1 .ude.demmu. in ADHD.
56
66 BARKLEY
Others have argued that the cognitive deficits in ADHD may arises from an underfunctioning of the brain's behavioral inhibi-
best be understood as a motivational deficit (Glow & Glow, tion system. That system is said to be sensitive to signals of
1979) or as arising from poor stimulus control, a diminished conditioned punishment, and the model predicts that those with
sensitivity to reinforcement, or deficient rule-governed behavior ADHD should prove less sensitive to such signals, particularly
(Barkley, 1981, 1989; Haenlein & Caul, 1987). Such views, in passive avoidance paradigms (Milich, Hartung, Martin, &
however, were not widely adopted, nor did they serve as an Haigler, 1994; Quay, 1988b). The second exception is the work
impetus to much new research. Zentall (1985) set forth an of Sergeant and van der Meere ( 1988; Sergeant, 1995a, 1995b,
optimal stimulation theory of ADHD, arguing that the hyperac- 1996; van der Meere, in press; van der Meere, van Baal, &
tivity arises from low levels of arousal and serves to maintain Sergeant, 1989), who successfully used information-processing
an optimal arousal level; the hyperactivity, in a sense, is a form of theory and its associated energetic model (arousal, activation,
self-stimulation. More recently, researchers theorizing on ADHD and effort) for isolating the central deficit(s) in ADHD within
have emphasized poor behavioral inhibition as the central im- that paradigm (Sergeant, 1995b). However, this approach does
pairment of the disorder (Barkley, 1990, 1994; Quay, 1988a; not set forth a theory of ADHD; like the Quay-Gray theory, it
Schachar, Tannock, & Logan, 1993; Schachar, Tannock, Marri- makes no effort at large-scale theory construction so as to pro-
ott, & Logan, 1995). vide a unifying account of the various cognitive deficits associ-
In keeping with this trend, in this article I attempt to provide ated with ADHD. Apart from these exceptions, the current clini-
a unifying model of ADHD that is founded on prior theories of cal view of ADHD (i.e., that of the DSM-IV) and the vast
the neuropsychological functions of the brain's prefrontal lobes. majority of current research being conducted on its nature are
Poor behavioral inhibition is specified as the central deficiency not theory driven (Taylor, 1996). One sign of advancement in
in ADHD. The model then sets forth a linkage between response a scientific field is that its research becomes so driven. This
inhibition and four executive functions that depend on such synthesis is an attempt to move research on ADHD further along
inhibition for their own effective performance. These four func- in that direction.
tions serve to bring behavior under the control of internally Douglas's (1980) earlier model of ADHD is not actually a
represented information and self-directed actions. By doing so, theory; it is mainly descriptive and was arrived at inductively
the four functions permit greater goal-directed action and task from a review of the extant research findings on ADHD in which
persistence. The model provides a more comprehensive account Douglas (1980, 1983; Douglas & Peters, 1979) discerned a
of research findings on the cognitive deficits associated with pattern among the findings consistently noted in this field. That
ADHD than does the current clinical view, which sees ADHD pattern comprised the four deficiencies noted earlier. Although
as primarily an attention deficit. The model also predicts many it was tremendously helpful at the time, such pattern discernment
additional deficits likely to be associated with ADHD that have remains at a descriptive level, albeit one more synthetic than
received little or no testing in research. Such predictions provide prior efforts at conceptualizing ADHD. But it is neither explana-
avenues for attempts at falsification of the model and point to tory nor, more important, predictive of new hypotheses that are
new areas for scientific investigation. testable. It still begs the question of just how the pattern itself
The goal here is admittedly ambitious, perhaps overly so, is to be explained. Appealing to the construct of self-regulation
because the model I propose may be potentially misconstrued (Douglas, 1988) is a step in the right direction but is of only
as a "theory of everything." Yet its boundaries are generally modest help unless self-regulation itself is defined and the man-
circumscribed to the domain of self-regulation in developmental ner in which it leads to the four impairments is explained. Both
psychology or executive functions in neuropsychology. Albeit a the pattern and the later use of self-regulation as an explanatory
broad domain, it is not unlimited. It can be readily distinguished construct by Douglas fit well within the model developed below.
from other major domains of neuropsychological functioning This theory, however, goes much further by providing the needed
such as sensation and perception, memory, language, and the definition of self-regulation, articulating the cognitive compo-
spatial, sequential, emotional, and motivational domains, among nents that contribute to it, specifying the primacy of behavioral
others. The model may overlap with these other domains, how- inhibition within the theory, and setting forth a motor control
ever, to the extent that self-regulation may affect them. Before component to ADHD. Most important, the model reveals a diver-
I proceed to discuss the origins of the model, its components, sity of new, untested, yet testable predictions about cognitive
and its extension to ADHD, the ambitiousness of this undertak- and behavioral deficits deserving of study.
ing demands a justification for why a new model of ADHD is A second reason why a theory of ADHD is sorely needed is
even necessary at this time. that the current clinical view of ADHD (i.e., that of the DSM-
/V), being purely descriptive of two behavioral deficits (inatten-
tion and hyperactivity-impulsivity), also cannot readily account
The Need for a New Model of ADHD
for the many cognitive and behavioral deficits associated with
A new theory of ADHD is needed for a number of reasons. ADHD that are reviewed later in this article. To account for
First, current research on ADHD is nearly atheoretical, at least such findings, any model must fulfill at least five key require-
in regards to its basic nature. That research is mainly exploratory ments: (a) It must explain why an actual deficit in attention in
and descriptive, with two exceptions. One is Quay's (1988a, children with ADHD has not been found (Schachar et al., 1993,
1988b, 1996) use of Gray's (1982) neuropsychological model 1995; Sergeant, 1995a, 1995b; van der Meere, in press; van der
of anxiety to explain the origin of the poor inhibition seen in Meere & Sergeant, 1988a, 1988b, 1988c), even though research
ADHD. This Quay-Gray model states that the impulsiveness on parent and teacher ratings of ADHD repeatedly identifies a
INHIBITION AND ADHD 67
factor of "inattention"; (b) it must explain the link between The deficit in the combined type of ADHD has been character-
poor behavioral inhibition (hyperactivity-impulsivity) and this ized as being in the realm of sustained attention (persistence)
sister impairment of inattention, or whatever this symptom turns and distractibility. If this distinction is valid, the present clinical
out to be; (c) it also must link these two constructs with execu- view of ADI-ID may be clustering into a single set of disorders
tive or metacognitive functions because most, if not all, of the what are, in reality, two qualitatively different disorders. Such a
cognitive deficits associated with ADHD seem to fall within the distinction would also argue that children with ADHD combined
realm of self-regulation or executive functions (Barkley, 1995; type who may develop the inattentive type as they get older
Denckla, 1994, 1995; Douglas, 1988; Grodzinsky & Diamond, (because of reductions in hyperactive behavior) are not actually
1992; Pennington & Ozonoff, 1996; Pennington, Grossier, & changing types of ADHD at all. The type of inattention that
Welsh, 1993; Seidman et al., 1995; Torgesen, 1994; Welsh, Pen- they continue to manifest (lack of persistence and distractibility)
nington, & Grossier, 1991; Weyandt & Willis, 1994); (d) it is still qualitatively different from the inattention manifested by
must ultimately connect the literature on ADHD with the larger children classified as the inattentive type. Any new theory of
literatures of developmental psychology and developmental neu- ADHD needs to address this emerging distinction. The model
ropsychology as they pertain to self-regulation and executive presented here provides a means of testing this dissociation
functions if it is to argue that ADHD arises from a disruption between types of inattention by using functional neuroimaging
in developmental processes; and (e) it must be useful as a scien- methods along with measures of the executive functions whose
tific tool and must make explicit predictions about new phenom- deficiencies are linked in this model to the hyperactive-impul-
ena that will both drive research initiatives and provide a means sive types of ADHD.
of falsifying the theory.
A third reason for a new model of ADHD is that the current
Clarification of Terms and Assumptions
view treats the subtypes of ADHD as sharing qualitatively identi-
cal deficits in attention while differing only in the presence of The term ADHD is used here to refer only to that subgroup
hyperactive-impulsive symptoms. As noted above, it is doubtful of this population previously identified as hyperactive (Chess,
that the problems with inattention associated with hyperactive- 1960), hyperkinetic (APA, 1968 ), attention deficit disorder with
impulsive behavior lie in the realm of attention, whereas those hyperactivity (APA, 1980), ADHD (APA, 1987), or, more re-
seen in the predominantly inattentive type of ADHD appear cently, ADHD-combined type and hyperactive-impulsive type
to do so. A digression is necessary here. The predominantly (APA, 1994). In this article, ADHD and the model of it devel-
hyperactive-impulsive type actually seems to be a develop- oped here do not refer to that subgroup whose chief problem is
mental precursor to the combined type. In the field trial for inattention alone (predominantly inattentive type).
ADHD in the DSM-IV, this hyperactive-impulsive type was The model set forth below presumes that the essential impair-
chiefly found among preschool children (Applegate et al., ment in ADHD is a deficit involving response inhibition. This
1995 ). In contrast, the combined type was far more represented deficit leads to secondary impairments in the four neuropsycho-
in school-aged children, as was nearly the entire sample of the logical abilities that are partially dependent on inhibition for
inattentive type. This relationship of ADHD type to the ages their effective execution. These secondary impairments then lead
associated with it likely arises from a simple observation made to decreased control of motor behavior by internally represented
in prior studies. The hyperactive-impulsive behavior pattern information and self-directed action. One consequence of this
seems to emerge first in development, during the preschool hierarchical relationship is that improvement or amelioration of
years, whereas the symptoms of inattention associated with it the inhibitory deficit should result in improvement or normaliza-
appear to have their onset several years later, at least according tion in the four executive functions that depend on it and also
to parental reports (Hart, Lahey, Loeber, Applegate, & Frick, in improved motor control. Another consequence is that this
1995; Loeber, Green, Lahey, Christ, & Frick, 1992). Moreover, successive chain of impairments creates the appearance of poor
the types of problems with inattention seen in the predominantly sustained attention in those with ADHD. However, this inatten-
inattentive type appear to have their onset even later than those tion actually represents a reduction in the control of behavior
that would eventually be associated with hyperactive-impulsive by the internally represented information contributed by these
behavior (Applegate et al., 1995). four executive functions. That information permits the tracking
Returning, then, to the start of this digression, it appears that of the adherence of behavior to it (i.e., rules, plans, intentions,
the predominantly inattentive type may not, in fact, have its goals, time, etc.), thus creating goal-directed persistence.
impairment in the same form of attention as that found in the Behavioral inhibition refers to three interrelated processes:
other two types (see Barkley, 1990; Barkley, Grodzinsky, & (a) inhibition of the initial prepotent response to an event; (b)
DuPaul, 1992; Goodyear & Hynd, 1992; Hinshaw, 1994; and stopping of an ongoing response, which thereby permits a delay
Lahey & Carlson, 1992, for reviews). Research on the inatten- in the decision to respond; and (c) the protection of this period
tive subtype suggests that symptoms of daydreaming, "spacing of delay and the self-directed responses that occur within it
out," being "in a fog," being easily confused, staring frequently, from disruption by competing events and responses (interfer-
and being lethargic, hypoactive, and passive are more common ence control). It is not just the delay and the self-directed actions
(Barkley, DuPaul, & McMurray, 1990; Lahey & Carlson, within it that are protected but also the eventual execution of
1992). This type of ADHD has a deficit in speed of information the goal-directed responses generated from those self-directed
processing, generally, and in focused or selective attention, spe- actions (Bronowski, 1977; Fuster, 1989). The prepotent re-
cifically (Goodyear & Hynd, 1992; Lahey & Carlson, 1992). sponse is defined as that response for which immediate rein-
68 YELKRAB
forcement (positive or negative) is available or has been pre- chically (or pyramidally) perched on it to assist in self-
viously associated with that response. The inhibitory process regulation.
involved in interference control may be separable from that Self-regulation is any response, or chain of responses, by the
involved in the delay or cessation of a response. Nevertheless, individual that serves to alter the probability of the individual's
the previous neuropsychological models on which the present subsequent response to an event and, in so doing, functions to
one is based clustered these processes together. That fact, along alter the probability of a later consequence related to that event
with research reviewed below which suggests that all three in- (Kanfer & Karoly, 1972; Skinner, 1953). These self-directed
hibitory activities are impaired in ADHD, has led to their treat- behaviors need not be publicly observable, although it is likely
ment here as a single construct. that in early development many of them are. Over development,
This definition of inhibition is not exactly the same as that they may become progressively more private, or internal-cogni-
used by Kagan, Reznick, and Snidman (1988) to study shy tive, in form. The development of internalized, self-directed
(inhibited) and sociable (uninhibited) children. In Kagan et speech, to be discussed later, may serve to exemplify this pro-
al.'s research, uninhibited behavior is defined by reactions to cess. Although eventually private, these actions remain essen-
social settings involving unfamiliar people in which children tially self-directed forms of behavior. The term executive func-
are consistently sociable, talkative, and affectively spontaneous. tion refers to these mainly private (cognitive) self-directed ac-
It is the polar opposite of shyness (clinging, quiet, timid, and tions that contribute to self-regulation. So defined, the term
withdrawn behavior). In contrast, inhibition is assessed by per- incorporates most of the attributes often ascribed to it by others
formance on cognitive and behavioral tasks that require with- (Denckla, 1994; Stuss & Benson, 1986; Torgesen, 1994;
holding of responding, delayed responding, cessation of ongoing Welsh & Pennington, 1988), including (a) self-directed actions;
responses, and resisting distraction or disruption by competing (b) the organization of behavioral contingencies across time;
events. The social characteristics of children with low social (c) the use of self-directed speech, rules, or plans; (d) deferred
inhibition in Kagan et al.'s research may be similar to some of gratification; and (e) goal-directed, future-oriented, purposive,
the behavioral effects in the model developed here. The two or intentional actions.
concepts and their correlates, however, do not appear to map A conflict between the immediate and distal consequences of
an act may be critical for identifying those circumstances that
precisely onto each other, nor do they seem to predict the same
serve to initiate inhibition and self-regulation (Kanfer & Karoly,
outcomes.
1972). Inhibition and its related executive functions may be
For instance, Caspi and Silva (1995) found that separate
most obvious (and most needed) when a delay of a consequence
dimensions of temperament for undercontrolled behavior (im-
is imposed in a task, when a conflict is confronted between the
pulsive, emotionally reactive, easily frustrated, and overactive)
immediate and delayed consequences of a response, or when a
and for socially confident behavior (sociable, talkative, and ea-
problem arises that requires generating a novel response to re-
ger to explore unfamiliar contexts) could be extracted from
solve it. Time, conflicts in temporally related outcomes, or nov-
ratings of 3-year-olds. These two dimensions predicted very
elty of a response, therefore, may serve as initiating events for
different personality characteristics in adulthood, with the for-
these executive functions. The future consequence is not actively
mer associated with more maladaptive behavior than the latter.
influencing this process because it has not yet occurred. Instead,
The undercontrolled behavior pattern seems more closely related
conditioned signals of punishment from experiences and prior
to the poor inhibition in the present model than is the socially
socialization may be the determinants of when inhibition and
confident pattern, which resembles Kagan et al.'s (1988) socia-
self-regulation are engaged (Quay, 1988a). When such initiating
ble (uninhibited) children.
events arise, self-regulation can result in a reduction in immedi-
This is hardly the first article to argue that behavioral inhibi-
ately available rewards (self-imposed deprivation) or an in-
tion is a central impairment in ADHD. Distinctive of the model
crease in the aversive consequences in the immediate context
to be offered here, however, is its linkage of this deficiency
(self-imposed pain or hardship). Yet these self-directed acts
in inhibition to the disruption of five other neuropsychological
may result in later, considerably larger, rewards or the avoidance
abilities that depend on inhibition for their efficient execution.
of later, and greater, aversive consequences. The net gain of
Four of these abilities are critical for self-regulation and goal- considering both the immediate and delayed consequences
directed persistence, so they are called executive functions here. would be greater than that achieved by consideration of the
ADHD is believed to disrupt these executive functions because immediate consequences alone (Kanfer & Karoly, 1972; Thore-
the first executive, self-regulatory act must be inhibition of re- sen & Mahoney, 1974).
sponding. Such inhibition permits a delay in the decision to Circumstances or tasks that involve temporal delays, conflicts
respond that is used for further self-directed, executive actions. in temporally related consequences, or the generation of novel
Those actions affect the decision to respond and control the responses most heavily tax the type of behavioral inhibition
eventual responses these executive functions generate. and self-regulation described here. Tasks requiring resistance to
This is not to say that behavioral inhibition directly causes temptation or deferred gratification are of this sort. Among the
these executive or self-directed actions to occur. However, it several dimensions of impulsivity discovered in past research
does set the occasion for their performance by providing the (behavioral and cognitive-motor, typically; Milich & Kramer,
delay necessary for them to occur. These four executive func- 1985; Olson, 1989), it is that dimension reflected in deferred
tions, therefore, should be viewed as neuropsychological sys- gratification and resistance to temptation, or what others have
tems separate from the behavioral inhibition system yet hierar- also called "behavioral inhibition" (White et al., 1994), that
INHIBITION AND ADHD 69
is associated with the inhibitory processes described here. Prob- (a) the incorporation of portions of Fuster' s ( 1989, 1995 ) theory
lem-solving tasks are also likely to tax behavioral inhibition and the views of others (Knights, Grabowecky, & S cabini, 1995;
and its related executive functions. By definition, problems era Milner, 1995) on the neuropsychological functions subserved
situations for which the individual has no readily available re- by the prefrontal cortex into a new hybrid model; (b) the inclu-
sponse and that require the generation of a novel response to sion of more precise definitions of behavioral inhibition and
resolve. And so problem-solving tasks, tasks involving temporal self-regulation; (c) the addition of a motor control-fluency-
delays, and tasks involving temporal conflicts in outcomes syntax component to the model; (d) the inclusion of the self-
would all prove useful in research studying not only the linkages regulation of drive and motivation as well as that of emotion in
between behavioral inhibition and the four executive functions the model; (e) the reconfiguration of the model components
in development but their impairment in ADHD as well. more logically than before (Barkley, 1994); (f) the addition of
It is the behavioral dimension of impulse control, rather than numerous recent findings bearing on the linkages among these
the cognitive dimension of impulsiveness (as measured by the components and their applicability to ADHD; and (g) additional
Matching Familiar Figures Test and the Draw-A-Line Slowly predictions about ADHD.
Test), that seems to be most stable over development, to corre- In some sense, the evidence reviewed in this article in support
spond most closely to parent or teacher ratings of hyperactive- of the hypothesized link between inhibition and executive func-
impulsive behavior, and to correlate most highly with later cog- tions, and even the extension of Bronowski's (1967, 1977) the-
nitive and social competence (Mischel, Shoda, & Peake, 1988; ory to ADHD, would have been anticipated by his theory and
Olson, 1989; Silverman & Ragusa, 1992). This may explain could be viewed as subsequent validation of it. The model devel-
why methods of assessing the behavioral type of inhibition (par- oped here also includes the later theory of Fuster (1989, 1995 )
ent-teacher ratings, delayed reward tasks, and reinforcer con- on the neuropsychological functions of the prefrontal cortex,
flict tasks) have been more useful than those assessing cognitive which was drawn from his extensive review of the animal and
impulse control in distinguishing those with ADHD from those human neuropsychological literatures pertaining to these func-
without it, in predicting which infants and preschool children tions. Though developed independently, and for somewhat differ-
are at risk for ultimately developing ADHD, and in predicting ent purposes, Bronowski's and Fuster's models have a substan-
the extent of later cognitive and social problems associated with tial number of similarities, so their combination into a hybrid
ADHD, as shown below. model of behavioral inhibition and executive functions makes
sense. Space permits only a brief summary of these two earlier
The immediate purpose of the four executive functions de-
theories to illustrate their many points of overlap.
scribed below seems to be the achievement of greater prediction
and control over the individual's own behavior and environment,
but their ultimate purpose seems to be an alteration in the future Bronowski's Theory on the Uniqueness
consequences a response is likely to produce (Bronowski, 1977; of Human Language
Fuster, 1989; Skinner, 1953). Such executive functions likely
Bronowski (1977) identified four unique properties of human
arise from (a) the development of neural networks within the
language that distinguish it from the languages of animals. He
prefrontal lobes, which underly these neuropsychological abili-
argued that human language is distinctive because it is not sim-
ties and permit the acquisition of more specific skills used for
ply a means of communication but of reflection, during which
self-control (Bronowski, 1977; Fuster, 1989); (b) the success
plans of action are proposed, played out, and tested. Reflection
these actions have had in the past for maximizing the net conse-
can only happen if there is a delay between the arrival of a
quences of behavior, both immediate and delayed, when consid-
stimulus or event and the response to that event. Bronowski
ered across long time periods (Kanfer & Karoly, 1972); (c) the
treated this capacity to inhibit and delay responses as the central
socialization of the child; and (d) the ongoing reinforcement of
and formative feature in the evolution of the unique features of
the individual for using self-regulatory actions (Hayes, 1989;
human language. It is not just the response that is being delayed
Kopp, 1982; Skinner, 1953). The teleological trap set here by
but the decision to respond (Bronowski, 1976). Four conse-
the use of terms that connote future, purpose, or intent can be
quences flow from the evolution of this ability to inhibit and
dealt with by recognizing that such apparently future-directed
delay responses: prolongation, separation of affect, internaliza-
behaviors are actually determined by experience and by ongoing
tion, and reconstitution. The capacity to delay responses as well
self-directed actions such as self-directed speech and self-
as the four consequent mental functions flowing from it are
directed imaging (Foster, 1989).
attributed to the brain's prefrontal cortex.
noitagnolorP is the ability to refer backward and forward in
time and to exchange messages with others that propose action
Origins of the Model in the future. This prolongation of reference, or the relation of
past events to future actions, requires a special form of memory.
Much of the present model linking inhibition to four executive During the delay in responding, the features of the signal, situa-
functions was set forth by Bronowski (1967) 30 years ago. tion, or event must be briefly prolonged, fixed, and held in some
Bronowski's theory has been discussed in more detail elsewhere symbolic form, so they can be retained for later recall when
as it pertains to ADHD (Barkley, 1994). The present explication they will serve to revive the responses associated with them in
differs substantially from the initial application of Bronowski's the future. The recall of the past and the manipulation of the
ideas to ADHD (Barkley, 1994, 1995 ) in the following respects: imagery of recall permit the construction of hypothetical situa-
70 YELKRAB
tions and their associated consequences. From such conjectur- private, inaudible speech and finally to fully private, subvocal
ing, plans can be formulated and anticipatory behaviors initi- speech (Berk, 1986, 1994; Berk & Garvin, 1984; Berk & Potts,
ated. This form of memory is, in a sense, remembering so as 1991; Bivens & Berk, 1990; Frauenglas & Diaz, 1985; Kohlberg,
to do. It is similar to the contemporary concept of working Yaeger, & Hjertholm, 1968).
memory in neuropsychology (for reviews, see Becker, 1994). The internalization of language brings with it the fourth con-
For instance, Goldman-Rakic (1995) defined working memory sequence of inhibition, which Bronowski (1977) called recon-
as "the ability to keep an item of information in mind in the stitution. It comprises two processes. The first is analysis, which
absence of an external cue and utilize that information to direct is the decomposition of sequences of events or messages into
an impending response" (p. 57). This form of memory and their parts. This allows the progressive redistribution of the event
the prolongation of reference it affords are said to permit both or message to other parallel information-processing systems
imagination and the concept of time. The recall of the past surely within the brain
is of the self-past, and the holding in mind of present events is the
self-present, both of which should contribute to self-awareness. os that its cognitive content becomes more particularized, dna sti
Thus are the functions of working memory, hindsight, fore- evitatroh content more generalized .... ehT physical world is pic-
thought, anticipatory set, sense of time, and self-awareness de- tured sa made up of units that can be matched in language, dna
pendent on inhibition. human language itself thereby shifts sti vocabulary from dnammoc
A second, subsidiary consequence of inhibition and response ot description or predication. (Bronowski, ,7791 .p 121 )
delay is the separation of affect. This refers to the separation
of the emotional charge from the content of a message or event The second process is synthesis, wherein these parts can be
and, as a result, the separation of the emotional valence from manipulated and used to construct or reconstitute entirely new
the content of the response to the event. This involves the self- messages or responses to others. In addition, because the units
regulation of emotion apart from motor behavior, and it affords in such messages can represent and initiate units of behavior,
the generation of neutral responses despite emotionally provoca- those behavioral units also can be reconstituted into entirely
tive events that may elicit highly charged feelings within the novel behavioral structures. This gives a synthetic and increas-
individual. Examples include remaining silent or speaking ingly hierarchical structure to both human language and behav-
calmly when angered. ior. Increasingly complex, novel units come to be formed out
The delay between event and response also permits time for of more elemental ones, and thus a layered structure to behavior
the event to be referred to more than one center in the brain is created. Reconstitution, it is argued, creates the potential for
and gives rise to an inner discussion of alternatives before a original productivity in human language and hence in the human
response is formed. This internalization of language gives a actions controlled by that language (Bronowski, 1977). The
unique form to human thought and speech. During the delay in rules or syntax for the sequencing of these verbal and behavioral
responding, language comes to be turned on the self. It thereby productions are an inherent part of the process of reconstitution.
moves from being primarily a means for communication with Reconstitution is quite evident in verbal fluency and discourse
others to one of communication with the self, a means of reflec- because they represent the capacity to rapidly access and recon-
tion and exploration that permits the construction of hypothetical stitute parts of speech into complete messages for others. The
messages or responses before one is chosen to utter or perform. speed, accuracy, fluency, syntax, and general efficiency with
It also permits the creation of self-directed instructions and which cognitive content is translated into units of speech and
thereby becomes a fundamental tool for self-control. In support- then into whole messages to others reflect the synthetic function
ing his assertions, Bronowski ( 1967, 1977) referenced the views of reconstitution. Verbal reconstitution should be most evident
of Vygotsky (1978, 1987), so they are briefly discussed here. in confrontational language tasks or in goal-directed speech or
Vygotsky's (1978, 1987) theory on the development of pri- writing, where ideas must be rapidly conveyed to achieve the
vate speech remains the most accepted view on the topic at this goal of the task. However, it should also be evident in goal-
time (Berk, 1994). Such speech starts out as "speech uttered directed behavioral creativity in general because this reflects the
aloud by children that is addressed either to the self or to no capacity to generate a variety of novel, complex sequences of
one in particular" (Berk & Potts, 1991, p. 358). In its earliest behavior directed toward goals. Various hypothetical futures and
stages, it is thought spoken out loud that accompanies ongoing the potential responses to them can now be internally simulated
action. As it matures, it functions as a form of self-guidance and tested before one is executed.
and direction by assisting with the formulation of a plan that Bronowski (1977) attributed these four executive functions
will eventually assist the child in controlling his or her own to the prefrontal lobes. Consequently, theories of and research
actions (Berk & Potts, 1991 ). Gradually, speech becomes pro- findings on the functions subserved by this cortex may have
gressively more private or internalized, and behavior comes in- some bearing on the many questions left open by Bronowski's
creasingly under its control; private speech thus becomes inter- theorizing. They may also have something to say about ADHD,
nal verbal thought that can exert a substantial controlling influ- given that the origin of ADHD has been repeatedly ascribed to
ence over behavior. This internalization of speech proceeds in this same brain region (Benton, 1991; Heilman, Voeller, & Na-
an orderly fashion. It seems to evolve from more conversational, deau, 1991; Mattes, 1980). Several neuroimaging studies also
task-irrelevant, and possibly self-stimulating forms of speech support this view (Castellanos et al., 1994; Lou, Henriksen, &
to more descriptive, task-relevant forms and then on to more Bruhn, 1984; Lou, Henriksen, Bruhn, Borner, & Nielsen, 1989;
prescriptive and self-guiding speech. It then progresses to more Rapoport, 1996; Sieg, Gaffney, Preston, & Hellings, 1995).
INHIBITION AND ADHD 71
Fuster's Theory of Prefrontal Functions completely disrupt the planning taking place. Internal sources
may also interfere, such as traces of information still held in
Fuster's ( 1989, 1995) theory of prefrontal functions was pro- working memory from the formation of immediately previous
posed apparently independently of Bronowski's (1977) model, behavioral structures. This retention of previous motor plans
yet the two have much in common. Fuster concluded that the past their timeliness and term can lead to perseveration of re-
overarching function of the prefrontal cortex is the formation sponding. Old habits more familiar to the individual or having
of cross-temporal structures of behavior that have a unifying similarity to ongoing behavior may likewise disrupt this syn-
purpose or goal. It is the novelty of these behavioral structures, thetic, goal-directed function, as might impulses to immediate
and especially the temporal discontiguities among their ele- gratification.
ments, that makes the prefrontal cortex essential in their forma- The dissociation of an inhibitory function from a working
tion. To a lesser extent, their complexity may additionally neces- memory function is not only conceptual but neuroanatomical
sitate the involvement of the prefrontal cortex. However, com- as well. The inhibitory functions are ascribed to the orbital-
plexity alone is not sufficient to place such acts within the frontal regions of the prefrontal cortex and its reciprocal inter-
purview of the prefrontal cortex. On the other hand, time being connections with the ventromedial region of the striatum (Iver-
inserted between the elements of the contingency (i.e., event, son & Dunnett, 1990). The functions of working memory are
responses, and consequences) would be sufficient to do so. Sim- subserved by the dorsolateral region of the prefrontal cortex
ilarly, novelty of the response would also lead to involvement and its reciprocal connections to the more central region of the
of the prefrontal lobes. striatum (Iversen & Dunnett, 1990). Substantial evidence from
It is this synthesis of novel, cross-temporal behavioral struc- neuropsychological and neuroimaging studies supports this dis-
tures mediating cross-temporal contingencies that requires the sociation (D'Esposito et al., 1995; Fuster, 1989, 1995; Goldman-
involvement of prefrontal functions. It is also the goal they Rakic, 1995; Iversen & Dunnett, 1990; Knights et al., 1995;
subserve that defines these behaviors and gives them cohesion Milner, 1995; Vendrell et al., 1995; Williams & Goldman-Rakic,
and direction. Smaller sequences of behavior linked over shorter 1995). Even within working memory, the retrospective (sen-
time periods can be used to create longer, more complex units sory) and prospective (motor setting) elements are likewise
of behavior with increasing durations and complexities and dissociable though interactive functions (Fuster, 1995; Gold-
longer term objectives. This pyramiding of simpler units of be- man-Rakic, 1995). Each may be subserved by separate, neigh-
havior into more complex ones produces a hierarchical structure boring, and interacting cortical regions in the dorsolateral pre-
to goal-directed behavior and bridges the temporal delays. This frontal lobes.
function is quite similar to Bronowski's (1977) concept of This capacity for holding events in mind in a correct temporal
reconstitution. sequence may give rise to the psychological sense of time (Mi-
Several functions must occur for behavioral structures to be chon, 1985). If so, time perception would be directly dependent
linked across time. qWo of these are temporally symmetrical on the integrity of working memory, as Bronowski (1977)
and are called retrospective and prospective functions. The retro- claimed. A subjective sense of time would seem to be critical
spective function entails the retention of information about past in Fuster's (1989, 1995) model as well, given his emphasis on
events that are held in their temporal sequence as they pertain the cross-temporal organization of behavior as being the major
to a goal. Such memory is provisional, having timeliness and function of the prefrontal cortex. A capacity for marking time
term, and permits the referring of current events to previous and sensing its passage would be essential to anticipatory setting
events in a sequence as well as the retention of action-related of motor responses in preparation for the arrival of impending
information derived from that analysis. The retrospective func- events. That sense would also be necessary for programming the
tion gives rise to formulation and retention of a goal-directed syntax or temporal structure of the complex behavioral chains
behavioral structure. This forms the prospective function, and generated in the service of goal attainment.
it leads to a preparation to act in anticipation of events or an The initiation and maintenance of cross-temporal, goal-
anticipatory set. The behavioral scheme and its relevant events directed actions require that the prefrontal cortex assist in regu-
are temporarily represented, deployed in the preparation to act lating basic drive or motivational states in the service of such
and the execution of those actions, and retained until the goal goal-directed acts. Otherwise, new behaviors would rarely be
has been accomplished. These functions are identical to Bro- initiated or sustained on the way to their intended goal. Hence
nowski's (1977) concepts of prolongation, hindsight, and fore- the self-regulation of drive and motivational states in the service
thought, as well as to the neuropsychological concept of working of goal-directed actions appears to be another function of the
memory (Fuster, 1989, 1995). prefrontal cortex. Fuster ( 1989, 1995) also recognized that dis-
Fuster (1989, 1995) argued that the proficiency of working orders of the prefrontal cortex often give rise to disturbances in
memory is dependent on response inhibition and interference the regulation of affective and emotional states. Yet he found
control, just as Bronowski (1977) had done. It is in working these difficult to interpret within his model. Bronowski (1977),
memory that goals and intentions to act are retained and that in contrast, made the separation and self-regulation of affect
action plans are formulated and used to guide the performance one of the major consequences of delayed responding in his
of the goal-directed responses. The delay in responding, during model. As discussed later, drive and motivation appear to be
which the cross-temporal behavioral structures are being formed part of the same functional brain system that governs emotion
and retained, is a critical time that requires protection from a (Lang, 1995), so the capacity to self-regulate affect may also
variety of sources of interference that can pervert, distort, or entail the capacity to self-regulate motivation.