زبان و عملکرد اجرایی در پرخاشگری تکانشی خودگزارش شده

The present study employed a battery of verbal tests that included a broad range of executive demands to demonstrate the differential contributions of language and executive function to the performance decrement observed in individuals who display impulsive aggressive (IA) outbursts. A profile analysis revealed that despite not differing on tasks requiring limited verbal output, the IAs deviated further from nonaggressive controls as the tasks required increasing spontaneous organization. Results suggest that language ability per se is not impaired in IAs; rather inefficient executive functioning is responsible for their significantly poorer performance on complex verbal tasks.

Each year, there are well over a million reports of violent crime and domestic battery in the United States (Bureau of Justice Statistics, 2000). These aggressive behaviors have profound social, legal, and political effects. As school violence increases and the age of violent offenders decreases, leaders, educators, and families have demanded answers to questions regarding the causes of aggression, the identification of those at risk for committing violent acts, and the prevention of these acts. The scientific community has responded with a bolstered interest in identifying predisposing factors of violence, a more descriptive classification system of aggression and aggressive acts (Barratt, 1991), recognition of associated behavioral, neurological, and physiological deviations (Barratt et al., 1997, Maughan et al., 1996 and Stanford & Barratt, 1996) and an effort to develop preventative strategies for at-risk individuals (Vance, Fernandez, & Biber, 1998), as well as the application of modification strategies to assist those who commit violent acts (Kellam, Mayer, Rebok, & Hawkins, 1998). Due to the heterogeneous nature of violence and aggression, a classification system is necessary to determine treatment options and facilitate the clinical, neuropsychological, and physiological description of the various types of violence and violent offenders. Barratt (Barratt et al., 1997) makes a clear distinction between premeditated and impulsive aggressive (IA) acts and the individuals who commit them. Premeditated acts are consciously executed or planned aggressive behaviors. Conversely, impulsive acts are an emotionally charged, uncontrolled type of aggressive display. This act can range in intensity from verbal aggression to homicide (Barratt et al., 1997 and Stanford et al., 1997). The impulsive aggressive individual displays intermittent aggressiveness grossly out of proportion to any precipitating psychosocial stressors. They frequently make poor decisions in problem solving situations (Kagan, 1966) and often react more aggressively in conflict situations (Olson & Hoza, 1993). Furthermore, impulsivity has been associated with increased risk-taking behavior, a younger age of first arrest, poor school performance, and increased behavior problems (Olson & Hoza, 1993, Richman & Lindgren, 1981, Stanford et al., 1996 and Vitelli, 1998). Subsequently, impulsive individuals are at greater risk for dropping out of school, engaging in criminal activities, and seeking out more stimulating environments. The destructive nature of an impulsive aggressive individual intensifies the need for accurate identification and treatment. One way to distinguish IAs from other violent or troubled populations is with cognitive testing. For example, IAs have problems with perceptual organization (Mungas, 1988), and fine and gross motor skills (Lewis et al., 1980 and Stanford et al., 1996). But the most noticeable, and perhaps most handicapping deficit is in the area of language. Highly aggressive individuals, including impulsive aggressive individuals, consistently score low in vocabulary, language and reading comprehension, receptive and expressive language, sentence repetition and completion, and verbal intelligence and memory (Harmon-Jones et al., 1997, Lewis et al., 1980, Richman & Lindgren, 1981, Spellacy, 1977 and Stanford et al., 1996). Impulsivity coupled with deficits in verbal ability has been related to delinquent activities, poor school performance, and increased behavior problems (Maughan et al., 1996, Miller, 1988 and Silva et al., 1987). Reading problems, in particular, have been associated with increased behavioral problems in female adolescents and an increased risk of juvenile offending among male adolescents (Maughan et al., 1996). Impulsiveness, as well as incidence of physical and verbal aggression, is inversely correlated with reading accuracy, reading comprehension, and verbal skills (Barratt et al., 1997, Harmon-Jones et al., 1997 and Stanford et al., 1996). Brinkley, Bernstein, and Newman (1999) studied the verbal output (telling a story) of psychopaths using a coherence/plot unit analysis. They reported a lack of cohesive ties in their narratives. That is, psychopaths resolved fewer plot units than controls. Furthermore, story guides that contained key plot elements hindered rather than helped their performance. Brinkley et al. (1999) suggest that psychopaths have more poorly organized speech than their nonpsychopathic peers. This investigation revealed a poor performance that could not be explained by impaired verbal ability only. A lack of organization reflects some executive problems. Executive function includes attention, concentration, concept formation, abstract reasoning, goal formation, social/self monitoring, hypothesis generation, set shifting in response to changing environmental demands, planning, temporal ordering, organization, associative learning, and inhibitory control (Fuster, 1997, Giancola, 1995 and Moffitt & Henry, 1989). Researchers have acknowledged executive deficits in impulsive aggressors, many in the context of verbal performance. Stanford et al. (1997) examined verbal and executive functions in IA college students using the same classification criteria as in the present study. They found significant group differences in verbal fluency and several scores on the Wisconsin Card Sorting Test (total correct, total errors, nonperseverative errors, percent conceptual level responses, categories completed, trials to first category, failure to maintain set). Specifically, IAs exhibited problems with verbal strategic processing and impulse control. Impulsivity and delinquency have been associated with deficits in verbal mediation, anticipation of consequences of actions, and conceptual integration (Miller, 1988). And among incarcerated delinquents, it has been found that the most violent individuals also had the most difficulty organizing their thoughts (Lewis et al., 1980). Many researchers that have provided support for an early link between language and aggression have also reported an association between executive deficits and aggression. For example, Camp (1977) has shown that young (6–8 years), aggressive males fail to use verbal mediation in problem solving strategies even when they have adequate verbal ability. Olson and Hoza (1993) also found consistent associations between conduct problems and language and executive deficits. They reported reduced vocabulary scores in females, as well as poor performance on delay-of-gratification tasks and more aggressive responses to conflict situations in males (ages 4–5 years). Silva et al. (1987) took a longitudinal approach in assessing the long-term effects of language problems. They evaluated children at ages 3, 7, 9, and 11 and found that those who were language delayed, and then slow in reading, not only showed these deficits at each evaluation, but also scored significantly higher than controls on behavior problems at home and in the classroom throughout their investigation. Maughan and colleagues (1996) determined the persistence of these correlates in early adolescents. They followed children who were identified as poor readers from 10 years old until 14 years old. They documented an increase in disruptive behavior into their teens, as well as increased inattentiveness at school. It appears that language and executive vulnerabilities, combined with a tendency toward impulsiveness, put individuals at a disadvantage, both academically and socially.