Page 1 03/04/01 POISSANT, Hélène
Third Antonio Borsellino College on Neurophysics
Scuola Internationale Superiore di Studi Avanzati (SISSA)
Evolution of Intelligent Behavior
23 April-4 May 2001
Miramare, Trieste, Italy
Metacognitive processes in children with attention deficit and hyperactivity disorder (ADHD)
Hélène Poissant, Ph.D
UQAM, DSÉ, C.P. 8888, Succ. Centre-ville
Montréal, P.Q. Canada, H3C 3P8
tél: 514 987 3000 (ext. 8946)
fax: 514 987 4608
E-mail:
Abstract
Metacognitive knowledge may be used in 4 ways:
· self-consciousness (know when) and (secondary ignorance (do not know when)
· know what (prediction and confidence in an outcome)
· know what ones needs to know (perception of lack of information/ inconsistencies of information)
· know the usefulness of some strategies
Self-regulation (S-r): experience, feelings, thoughts that occur during an ongoing cognitive activity. Those experiences give individuals an internal feedback about the efficiency of their mental monitoring.
S-r may be conscious
ADHD are unable to “stop and think” before acting.
We look at different kind of evidence: neurobiological, neuropsychological and medical and argue that individuals with ADHD may experience a lack of metacognition (: consciousness that individuals have about their own thinking processes and to the ability to have control of those processes)
Introduction
Prevalence of ADHD:
1%-3% in the American school-aged population
5%-10% of ADHD have other problems/psychiatric disorder (comorbidity): ODD, CD, anxiety, depression.
20%-30% of ADHD have LD
30% of ADHD have delayed motor skill development
3 boys: 1 girl develop ADHD.
30%-50% still manifest symptoms in adulthood
DSM-IV assessment of ADHD (1994):
1) Inattentive type:
a)fails to give close attention to details/makes careless mistakes, b) difficulty sustaining attention, c) does not appear to listen, d) struggles to follow through on instructions, e) difficulty with organization, f) avoids or dislikes requiring sustained mental effort, g) often loses things necessary for tasks, h) easily distracted, i) forgetful in daily activities.
· Hyperactive/impulsive type:
a)fidgets with hands/feet or squirms in seat, b) difficulty remaining seated, c) runs about or climbs excessively, d) difficulty engaging in activities quietly, e) acts as if driven by a motor, f) talks excessively, g) blurts out answers before questions have been completed, h) difficulty waiting in turn taking situations, i) interrupts or intrudes upon others.
Neurobiological Evidence
Heredity:
· 25 % of the fathers & 17-25% of the mothers of ADHD children have this condition
· ADHD aggregates in nuclear families
· 2nd-degree relatives of ADHD probands are at increased risk for ADHD
· relatives of girls with ADHD have higher risk of also being affected by this condition
· 75-91% chance that a twin (identical/nonidentical) has ADHD
· 13 to 35% chance that another child in the family has ADHD
Dopamine and frontal dysfunction:
dopamine pathways in the brain, which link the basal ganglia and frontal cortex play an important role in ADHD
[see Barkley, 1998]
ADHD have difficulty to inhibit response during a delay period (800-msec): associated with pathology located outside the dorsolateral prefrontal cortex
Areas in the prefrontal lobe, basal ganglia, and striatum are reduced by about 10%in size&activity (areas involved in response, attention, and sensitivity to reward)
In ADHD adults, the brain areas that control attention used less glucose, which indicates less activity
[ see Zametkin et al., 1990]
ADHD children differed from controls on tasks involving motor control and problem solving skills known to be sensitive to frontal lobe dysfunction.
ADHD children make more errors and react more slowly than controls in tests of sustained attention. Coincident with their poor performance, children with ADHD have smaller late positive components of the ERP
LD with or without ADHD both have smaller P3 wave amplitude compared to normal when all groups have to perform an auditory task (two-tone discrimination)
72.7% of normal children evidenced a left-larger-than-right pattern of asymmetry : 63.6% of the ADHD children had the reverse pattern of asymmetry (most notable in boys with ADHD
Right-handed male ADHD have smaller posterior corpus callosum regions than the control group (areas related to sustained attention deficits and to the development of self-regulation (still controversial)
Neuropsychological evidence
Now DSM-IV primary characteristics associated with ADHD(inattention, hyperactivity/impulsiveness) are challenged.
Barkley (1997,1998) points to “impulse control” rather than default in the filtering system of attention. For ADHD children, the urge to act is not controlled or inhibited, so that we may consider the child as hyper-responsive. By 4 years of age, normal children start to develop self-control along with an “internalized language”; ADHD children fail to do so and have difficulty to provide a delayed answer.
Barkley predicts that ADHD will have a poorer working memory. To be able to hold in memory an information, for even a very short period of time, enables the individual to analyze and reflect about this information. The inability to reflect and therefore to wait prevents the child from behaving in a proper way.
ADHD find it difficult to hold back their emotions and seem to feel them more intensively than average people. Such difficulties also lead to a lack of objectivity and consequently make goal-directed behavior less likely.
An important part in self-control and reflection, i.e., the internalized language, is impaired in ADHD. The ability to hold a thought enables humans to organize information and to elaborate new relations among this information that lead to a deeper understanding. The inability to do so gives the impression that ADHD have difficulty to explain things and do not get to the point but rather around the point.
The disorder in response inhibition and executive functions associated with ADHD have among consequences an impairment in self-regulation, an impairment in behavior organization toward the future (or planning), and an impairment in social effectiveness.
Tests of response inhibition reliably distinguished ADHD from normals. ADHD made more omission errors on a Continuous Performance Test and performed more poorly on the word and interference portions of the Stroop Test compared to normals.
Both types of ADHD shared similar deficits on some frontal lobe tests while difficulties related to perceptual-motor speed and processing were found only in predominantly inattentive type.
Medical evidence
Methylphenidate (MPH), a psychostimulant of the CNS, is well recognized to improve ADHD symptomatology.
MPH acts as a dopamine agonist and as such increases the level of available dopamine in the system (dopaminergic neurons are found in areas such as frontal lobe & limbic system, that are involved in the control of problematic behavior: e.g., motor control, impulsiveness).
Advantages of MPH:
better compliance to maternal commands, increase in persistence to tasks, improvement of working memory, improvement of social behavior with peers& adults as well as academic performance, and improvement on the Go-no-go-test (decrease in the tendency to make impulsive commission errors)
Improvement on tests sensitive to frontal lobe dysfunction such as: spatial working memory and planning.
Metacognitive functioning
Metacognitive knowledge is used in four different ways (Brown, 1978;1987; Markman, 1977):
1) individuals may “know when” they know (“self-consciousness”) or do “not know when” they do not know (“secondary ignorance”)
2) individuals may “know what” they know, which can help them to predict their abilities to succeed in a given task and to estimate their confidence in the outcome;
3) individuals may “know what they need ” to know to fill in their lack of information (“perception of lack of information”) or the inconsistencies in a given information (“perception of inconsistencies of information”);
4) individuals “may know the usefulness of strategies” for dealing with a given task.
[See figure 1 and 2 for an expansion of Brown’s “self-consciousness” and “secondary ignorance” concepts]
Metacognitive dysfunctioning
Metacognitive dysfunctioning: problem in the experience or feeling of conscious awareness of one’s own cognitive performance.
Disruptions of metacognition, characterized by cognition without awareness, can take many clinical forms such as memory without awareness.
The lack of awareness reported in some clinical cases suggests that many cognitive functions may operate without conscious control. This also suggests that cognitive functions have a componential aspect, that is neural circuits operating in parallel with other metacognitive functions. Thus different metacognitive impairments may involve different neural circuits depending on the type of cognitive functions that is disrupted.
This hypothesis seems to be confirmed in some neurological pathologies. For example, it was found that in organic amnesia patients certain aspects of new learning capacity (during a perceptual-motor skill task and a mirror-reading skill task) are preserved even though the patients did not have an awareness of their capacity or did not have a conscious recollection of having engaged in the task before.
This phenomena resembles, although in a reverse way, the “know when” component of metacognition, but here patients do not know when they know (:a special case of secondary ignorance).[see figure 2]
These findings suggest that certain parts of memory capacity, namely its conscious recollection component may be distinct of its unconscious automatic component.
The involvement of frontal lobe in feeling-of-knowing and metacognition seems to be confirmed by other studies (e.g., patients with frontal lesions impaired in the ability to judge what they had learned; Korsakoff’s patients impaired in their feeling-of-knowing accuracy in addition to deficits in encoding, attention and memory for temporal order).
According to Shimamura (1994), one possible explanation implies that frontal lobe damage mediates disorders of metamemory (:knowledge of one’s memory capabilities & strategies that can help memory). Deficits in metamemory expressed by failed judgments and decision making is consistent with other disorders related with frontal lobe dysfunctioning.
Patients with frontal lobe lesions do not experiment impairment in perception & memory but rather an impairment in the “evaluation or integration of these cognitive functions”.
The metacognitive impairment related to frontal lesions may be due to a failure to make appropriate “judgments” based on perceptual and semantic knowledge.
Hypothesis
We know that ADHD children may experience a deficit in executive functioning and we suspect that they also lack of metacognition.
Accordingly, these children might not notice the lack of information in a given instruction even at 8 years of age and up (“know-what-ones-need-to-know” component of metacognitive knowledge).
Method
Participants
· Control group (n = 30, overall mean age = 8.75) originate from a French public school
· ADHD group (n=17, overall mean age = 9.06) comes both from a neurological clinic and a special needs school (n=5).
· Site: Montreal suburban region. Subjects were all from the same socioeconomic background.
· Age groups: age group 1= 6-; age group 2= 8-9; age group 3= 10-11.5)
· School levels: 1st grade - 6th grade
Procedure
All subjects were administered the Conner’s Parent Rating Scale (CPRS-48) and the Conner’s Teacher Rating Scale (CTRS-28) to confirm the DSM-IV diagnostics of ADHD made by the neurologist and to screen for other disorders in controls as well. ADHD children were found to have a higher score on the hyperactivity index of the Conner’s Parent Rating Scale (CPRS-48) (t18.8 = 3.68, p= 0.0016) and on the Conner’s Teacher Rating Scale (CTRS-28) (t9.2 = 6.3591, p= 0.0001) than the normal children.
Perception of lack of information task
Following Markman (1977)’s procedure, the experimenter (E) gives verbally and individually to each child (C) the instructions regarding the performance of a “Magic Trick” and a “Game of Cards”. The instructions were intentionally designed to be incomplete. In the first task, E performs, while he describes it, a magic trick in front of C. First, E shows an empty cup, a plate, a penny and a sheet of paper. E makes sure that C sees that the cup is empty. Then, E puts the plate on the empty cup. Then, E wraps the penny in the paper sheet and puts it on the plate. Finally, E makes the wrapped penny slips from the plate into the cup. (In reality, E pretends to wrap the penny, and let it fall on his own lap. Then E puts the unwrapped penny into the cup, without letting the child know about it). C must discover what E had “forgotten ” (to mention how the penny could be find unwrapped into the cup, since it was wrapped in the first place). During the attempt of C to do the Magic Trick, E asks a series of ten questions (10) to help the child discover the missing information. In the Game of Cards, E tells to C that the goal of the game is to accumulate as much as possible “special cards”. At no point in time, E does explain what are those special cards. At the end of the instructions, C must find if the given instructions were complete or not. Then, E starts to play with C. While C is trying to play the game, E asks the same series of questions (10) to help the child.
To avoid any learning effect, the two tasks were performed within a two-month interval and in a counterbalanced way (Magic Trick - Game of Cards or Game of Cards - Magic Trick).
Results
ADHD: Age group 1: (M = 8.67, SD = 1.15; age group 2: M = 6.75, SD = 3.25 and age group 3: (M = 2.67, SD = 0.98.
Control: Age group 1: (M = 5.56, SD = 2.77; age group 2: M = 5.39, SD = 2.34 and age group 3: (M = 4.67, SD = 2.83.
See figure
Two-factors ANOVA (*):
Significant interaction between age groups (1-2-3) and identity factors (:ADHD Vs control), F (2,41) = 3.24, p = .0493.
Comparison of age groups within each identity (*):
The Bonferroni correction (significance level to 0.0083) indicates:
· ADHD: age group 3 performs significantly better than age group 2 (p = 0.0057) and than age group 1 (p = 0.0021)
· Controls: no age group difference
Comparison of identitywithin each age group:
Comparison of ADHD and Control: no difference.
Comparison of school levels (*):
Sensible effect for school level factor, F (5,41) = 2.07, p= 0.0891:
All subjects (ADHD& controls) perform better at the 6th grade Vs the 1st & 2nd grades,
· 1st grade: 6th grade, unadjusted t-test = 2.45, p= 0.0189;
· 2nd grade: 6th grade, unadjusted t-test = 2.85, p= 0.0069.
Discussion
Knowing-what-we-need-to -know is an important aspect of metacognitive knowledge. According to Markman, an instanciation of this aspect: the perception of a lack of information in an instruction, is acquired at around the age of 8 (age group 2 in our study) in normal children. In the present study, we have replicated Markman’s procedure with ADHD children to check for an eventual delay in this population. Contrary to our expectations, our results indicate no significant difference between ADHD and control children for all groups of age combined.