The effects of methylphenidate on various types of activity level and attention in hyperkinetic children

The effects of methylphenidate on a number of objective measures of activity level and attention were assessed on three repeated occasions in four types of settings: free play, movie viewing, testing, and restricted play periods. Subjects were 36 boys between 5 and 12 years of age and of average intelligence. Of these, 18 were diagnosed as hyperkinetic and participated in a double-blind drug-placebo crossover design. The remaining 18 boys, matched in age and IQ with the hyperkinetic children, served as a control group and received no drugs. Results indicated that compared to placebo, methylphenidate significantly reduced wrist, ankle, locomotor, and seat movement activity in the hyperkinetic children regardless of the type of setting in which the measures were taken. Relatively fewer significant drug effects were noted on the measures of concentration or attention. While concentration to reaction time, maze performance, and a movie viewing task improved during drug treatment, the length of attention to toys in free play was not significantly improved. Parental ratings of activity level were also improved by the drug. The hyperkinetic children were also observed to increase their level of task-irrelevant activity over time while control children remained relatively stable in activity over repeated assessment. Despite the positive drug effects, clinical observations suggested that methyl-phenidate may have reduced the interest of some children in their environment.     

Trait-anger enhances effects of caffeine on psychomotor vigilance performance

This study examined the combined effects of caffeine and the personality attribute of trait-anger on the speed of psychomotor vigilance performance during sleep deprivation. 23 young adult soldiers (19 male) were administered the State-Trait Anger Expression Inventory-2 when well-rested. Participants were then sleep deprived for three consecutive nights (77 hours total) during which they completed repeated psychomotor vigilance testing. Half of the participants received four doses of oral caffeine (200 mg every 2 hr.; 800 mg total) each night, while the other half were administered a placebo. For the first night, higher scores on trait-anger, outward anger expression, and intensity of anger expression predicted better sustained overnight vigilance performance, but only for those volunteers receiving caffeine. These correlations were not significant for the subsequent nights. Findings suggest a possible synergistic effect between personality traits associated with arousal of the central nervous system and vigilance-promoting effects of caffeine.     

Practice effects on fractionated response time related to age and activity level

Two days of practice on simple and choice reaction (RT) and movement time (MT) were studied using 60 males placed into four groups based upon age and physical activity level. Practice effects upon simple and choice RTs were different for young and old groups. Only the two inactive groups improved on simple and choice MT, with greatest improvement occurring on simple MT. Old Actives had true-score variance than the Old Inactives, but much greater than the two young groups. Intraindividual variability was greater for the two older groups even in the absence of practice effects. Results support the claim that a life style or regular physical activity may lessen aging effects upon RT and MT as well as attenuating interindividual variability.     

Intratask distractibility in hyperkinetic and nonhyperkinetic children

Previous laboratory studies that have either introduced extraneous environmental stimulation or tested children in cubicles have failed to provide support for the common clinical notion that hyperkinetic children are highly distractible. Based on the Rosenthal and Allen (1978) proposal, distractibility was investigated by introducing irrelevant information within the task context. Intratask distractibility was examined by comparing the performance of hyperkinetic and nonhyperkinetic children on a speeded classification task. Errors were measured for responses to slides containing either zero, constant, one varying, or two varying irrelevant stimulus dimensions. Dimensional salience of the three dimensions used in the study was measured for each child. The data indicate that hyperkinetics made more errors than nonhyperkinetics when constant irrelevant or two varying irrelevant dimensions were presented, but the two groups made equal errors when there was no irrelevant information presented within the stimulus array. No group differences in distractibility were found when the irrelevant dimension was low salience. It was concluded that salience of distractors presented within the task context may be useful in specifying the particular task conditions in which hyperkinetic children exhibit high distractibility. This study is based on the first author's Ph.D. thesis in the Department of Psychology, Vanderbilt University, Nashville, Tennessee. The authors wish to thank the many administrators, teachers, and students in the Metropolitan Nashville Public Schools for their cooperation, including Dr. Thomas Vandever, Mr. V. N. Nicholson, Dr. Jesse Cabler, Mrs. Elizabeth Wortham, and Mr. W. J. Officer.     

Predicting the response of hyperkinetic children to stimulant drugs: A review

The present review examines 36 previous research reports involving over 1,400 hyperkinetic children in an effort to determine which variables have proven useful in predicting which hyperkinetic children will respond favorably to stimulant drugs. The research is summarized under eight types of predictor variables: (1) psychophysiological, (2) neurological, (3) familial, (4) demographic/sociological, (5) diagnostic category, (6) parent/teacher/clinician ratings, (7) psychological, and (8) profile types. The results of this review indicate that, to date, measures of attention span or concentration and its correlates have proven to be the most useful predictors of the response of hyperactive children to drugs. The results also suggest that hyperkinetic children are heterogeneous with respect to levels of CNS arousal and that this variable may prove useful in predicting their response to stimulant drugs. Problems involved in drawing conclusions in a review of this area of research as well as directions which future research might pursue also are briefly discussed.     

The vigilance, orienting, and executive attention networks in 4-year-old children.

The present study examined the development of lower and higher order forms of attention during the preschool years. Lower forms of attention were assessed with tasks that primarily engaged the attention functions of vigilance and orienting. Higher, executive forms of attention were assessed with tasks that involved inhibition and working memory. The findings revealed that performance improved significantly with age on measures of inhibition and orienting. Results are discussed in the context of the development of attentional networks.     

The effects of caffeine and provocation on aggression

Thirty-nine men received 200 mg of caffeine and were led to believe that they had ingested either an arousing drug or a harmless placebo. They were then either provoked or not provoked by their partner during a bogus reaction-time task. After receiving four opportunities to deliver aversive tones to their partner, they were told that they had been mistakenly informed of their pill assignments and received four more opportunities to aggress. In accord with our manipulation of multiple sources of arousal, provoked relative to unprovoked participants attributed their feelings to both the drug and their partner's behavior. Contrary to predictions, angered subjects delivered more aversive tones when they thought they had taken a drug but reduced their aggression when subsequently told that they had ingested a placebo rather than an arousing drug. The results were discussed as being more consistent with a justification position than with Zillmann's excitation transfer position (in New directions in attribution research. J. H. Harvey, W. J. Ickes, & R. F. Kidd (Eds.), Hillsdale, NJ: Erlbaum, 1978, Vol. 2). As in other studies using drugs, participants seemed to use the drug as an excuse to release hostility.     

The relationship between intelligence and vigilance in children at risk

The purpose of this study was to compare two competing models as an explanation of the relationship between intelligence and sustained attention in educationally at-risk kindergarten children. One model assumes that lower-IQ subjects allocate greater amounts of attentional resources to information-processing tasks than higher-IQ subjects, whereas the other model assumes that a less-than optimal level of arousal is associated with decrements in task performance across time. Twenty-nine teacher-nominated at-risk and 29 normal achieving kindergarten students were administered the Wechsler Preschool and Primary Scale of Intelligence—Revised (WPPSI-R) and vigilance tasks. Signal detection measures of stimulus detectability (d), decision criterion (), correct detections, and false alarms were used to assess children's sustained attention across three time periods (2, 4, and 6 min). The important results were (a) high-risk children were inferior on dmeasures when compared to normal achieving children, (b) vigilance measures did not vary over time in either group, and (c) intelligence and vigilance shared a common factor in high-risk, but not low-risk, children. The results suggest that children educationally at risk suffer deficits related to attentional capacity for processing information. Special appreciation is expressed to Ron Jarman for his comments on the statistical analysis and the Courtenay School District, British Columbia, Canada, for providing participants. The authors also thank two anonymous reviewers who provided comments on an earlier version of this article.     

The effects of sleep deprivation on the attentional functions and vigilance

The study of sleep deprivation is a fruitful area of research to increase our knowledge of cognitive functions and their neural basis. In the current work, 26 healthy young adults participated in a sleep deprivation study, in which the Attentional Networks Test for Interactions and Vigilance (ANTI-V) was performed at 10a.m. after a night of normal sleep and again at 10 a.m. after 25.5-27.5 h of total sleep deprivation. The ANTI-V is an experimental task that provides measures of alerting, orienting and executive control attentional functions. Compared with previous versions, the ANTI-V includes a vigilance task, more reliable auditory alerting signals, non-predictive peripheral orienting cues, and also a neutral no-cue condition allowing the analysis of reorienting costs and orienting benefits. Thus, new evidence to evaluate the influence of sleep deprivation on attentional functioning is provided. Results revealed differences in both tonic and phasic alertness after sleep deprivation. Vigilance performance was deteriorated, while a warning tone was more helpful to increase participants' alertness, resulting in slightly faster RT and, in particular, fewer errors. The reorienting costs of having an invalid spatial cue were reduced after sleep loss. No sleep deprivation effect on the executive control measure was found in this study. Finally, since no control group was used, particular precautions were taken to reduce the influence of potential practice effects.     

Vibrotactile vigilance: The effects of costs and values on signals

Vibrotactile vigilance behavior was examined for the effects on signal detection performance of placing costs on misses and false detections and a positive value on the correct detection of a signal. Analyses over time showing that the frequencies of correct detection and false detection of signals decreased, while response times increased, indicated that increased costs for misses and false alarms lead to poorer correct detection performance, while the value placed on the correct detection of a signal had little effect. The d’ statistic of signal detection theory was invariant with both signal costs and time, while β varied with both factors.These results imply that the performance decrement during a vigil was due to an increased strictness in the criterion (β) the S set for deciding whether or not a signal was present. The cost factors were effective in manipulating performance during the watch by causing changes in the S’s decision criteria. Findings from this study clearly support those predicted by the “Decision Theory” of Swets, Tanner, and Birdsall (1961); this is suggested as perhaps being the best available basis for a theory of vigilance at this time.     

Effects of amphetamine on vigilance performance in normal and hyperactive children

Deficient sustained attention is a symptom of hyperactivity that can be improved by stimulant medication. Recently, amphetamine has been shown to increase detections during a vigilance task in both normal and hyperactive boys. The present study applied signal detection analysis to the vigilance performance of 15 hyperactive and 14 normal boys divided into two age groups (6–9 and 10–12). A computerized continuous performance test was administered under amphetamine and placebo. Overall group comparisons indicated that perceptual sensitivity or d was higher for the normal boys and the older groups, and analysis of drug treatments showed that amphetamine significantly increased d. Interactions between drugs and age groups demonstrated that amphetamine affected the younger boys to a significantly greater degree than the older children for both d and response bias or . It is notable that the results were essentially parallel for both normal and hyperactive children.     

The effects of different modes of supervision on vigilance behaviour.

Experiment I was run to determine if a closed-circuit television and a one-way window mode of supervision were as effective as the direct physical presence of an experimenter in inducing enhanced levels of signal detection in a Mackworth-type vigilance task. A control condition of complete subject privacy was also examined. The results indicated that both the television and the window conditions had a positive effect on overall performance which was similar to that observed in the experimenter-presence condition; however, the performance decrement over the 90 min vigil was equivalent for the four modes. A second experiment involving the variable of camera position with an addition of a fourth 30 min. period yielded no significant differences between the camera positions, but overall performance in the television condition was again better than in the control condition. This study suggested that performance can be enhanced even without the physical presence of the experimenter.     

Arousal and recognition memory: The effects of impulsivity,caffeine and time on task

Systematic changes in performance on memory tasks have been observed as a function of the number of prior items or lists learned. In an attempt to determine whether this was an ‘attentional’ phenomenon the effect of arousal (as indexed by Impulsivity and manipulated by caffeine) on memory performance was examined. One hundred college students were given either 4 mg of caffeine/kg body weight or a placebo and then shown four lists (two 24-item and two 80-item) of four letter words. A forced-choice recognition test for the last 20 items was given immediately after each list. The performance of the high impulsives who were given a placebo (least aroused subjects) declined as a function of the number of prior lists learned. Low impulsives (more aroused) showed significantly less decline. Caffeine significantly improved recognition memory especially on the final lists. Decrements in memory performance, as a function of number of prior litsts, are thus reduced by the same variables which reduce vigilance decrements. It is suggested that common explanations will be required.     

The effects of a response cost treatment tactic on hyperactive children

In a pilot study, a multielement design was used to assess the effectiveness of a response cost procedure on a 7-year-old child's hyperactive behavior and academic performance across days. The procedure was effective in reducing off-task behavior and in increasing academic assignment completion. In Experiment 2, three strategies were compared to a no-treatment baseline in treating an 8-year-old hyperactive child: drug (Ritalin) alone, response cost alone, and drug plus response cost. The cost program alone and the cost program combined with medication were effective in reducing off-task behavior and in increasing academic performance. In both studies, the procedure was viewed by the teachers as practical and effective for use in a classroom setting. The subjects liked the cost system and believed that they completed more academic work when it was operative.     

Effects of acute sleep restriction on behavior, sustained attention, and response inhibition in children.

This study examined the effects of acute sleep restriction on the day-time behavior and performance of healthy children and adolescents. 82 participants (8 to 15 years of age) completed 5 nights of baseline sleep and were randomly assigned to Optimized (10 hr.) or Restricted (4 hr.) sleep for an overnight lab visit. Behavior, performance, and sleepiness were assessed the following day. Sleep restriction was associated with shorter daytime sleep latency, increased subjective sleepiness, and increased sleepy and inattentive behaviors but was not associated with increased hyperactive-impulsive behavior or impaired performance on tests of response inhibition and sustained attention. Results are discussed in terms of current theories regarding effects of inadequate or disturbed sleep among children and adolescents.