Autonomic and behavioral effects of dextroamphetamine and placebo in normal and hyperactive prepubertal boys

The hypothesis is tested that the response to dextroamphetamine in terms of activity, attention, impulsivity, and autonomic activity is similar in normal (N) and hyperactive (H) children. Fourteen N and 15 H boys had skin conductance (SC), heart rate (HR), and finger temperature (ST) recorded during rest, presentation of eight 75- dB tones, and a reaction time (RT) procedure on three occasions: off drug (Day 1) and after ingestion (double-blind) of placebo and of .5 mg/kg dextroamphetamine. Both N and H groups showed drug effects, compared to placebo, of reduced motor activity and impulsivity, improved attention (RT), increased HR and HR slowing during RT foreperiods, and decreased ST. Both groups also had decreases in SC responsivity but in different parts of the test. Placebo compared to Day 1 produced increased activity and autonomic arousal but no change in RT. Stimulant drugs thus have similar behavioral and autonomic effects in both N and H boys, but the beneficial effects on behavior do not depend critically on increases in arousal.     

Determinants of tonic and phasic reactions in transswitching

Forty-eight college students were assigned randomly to four groups in a 2 × 2 factorial arrangement of phasic conditional stimuli (samevs. different) and tonic conditional stimuli (samevs. different) to receive 2 days of classical conditioning with a transswitching procedure. Tonic stimuli were a 5-minute projected white triangle or circle; phasic stimuli were a 5-second red or green square superimposed over the tonic stimuli. There were six tonic stimulus segments each day, separated by 20-second periods of no stimulus, three containing six trials of the phasic stimulus paired with shock and three containing six trials of the phasic stimulus alone, in the counterbalanced order. Tonic responding at the onset of the tonic stimuli or during brief periods following its onset were recorded, along with phasic responses to the phasic stimuli. Responses included magnitude of skin conductance responses, frequency of unelicited skin conductance responses, and tonic heart rate. Both skin conductance measures of responding to the tonic stimuli differentiated significantly between positive and negative tonic segments during Day 2, but only in the group with two different tonic stimuli and one phasic stimulus (“standard” transswitching). This supported the hypothesis that tonic stimulus differentiation would be absent when two different phasic stimuli were present. The heart rate data did not support this hypothesis, showing tonic differentiation in both groups with two tonic stimuli. Phasic differentiation controlled by the different phasic stimuli was observed on Day 1; on Day 2, phasic differentiation was present only in the group with two tonic and one phasic stimuli and the group with one tonic and two phasic stimuli. The results were interpreted to mean that temporal contiguity between the tonic stimuli and shock or no shock is not sufficient to establish tonic response differentiation in transswitching.     

Electrodermal measures of attention and effort to stimulus onset and offset for intramodal and intermodal tasks.

Two experiments were designed to assess the relationship between task difficulty and arousal. Electrodermal measures of tonic and phasic arousal to four levels of task difficulty at stimulus onset and offset were studied in college students for intramodal and intermodal tasks. The students were presented for 18 trails with visual-auditory or visual-visual stimuli with either 2.0-, 0.2-, or 0.02-sec difference between stimuli onset or offset, and asked to judge which stimulus came on or went off first or merely to observe the stimuli. Both frequency and amplitude of skin conductance responses reliably differentiated the levels of task difficulty for both the intramodal and the intermodal task. None of the measures of tonic level of arousal was reliable. Electrodermal measures of phasic responses accurately reflected the task demands.     

Stimulus Significance Effects in Habituation of the Phasic and Tonic Orienting Reflex

Phasic and tonic measures of electrodermal activity were examined in a simple habituation paradigm, using innocuous visual stimuli. Separate groups were used to investigate the effects of stimulus significance, as manipulated by instructions. One group had no stimulus-related task (indifferent group), while the other was asked to silently count the stimuli to report to the experimenter later (significant group). Prestimulus skin conductance levels were considered as measures of the arousal level at each stimulus presentation, and the subsequent electrodermal responses were taken as the phasic orienting reflex (OR) elicited by each stimulus. Changes in prestimulus arousal were taken as measures of the tonic OR to the experimental series. Marked group differences were found in both phasic and tonic components of the OR. Some, but not all, of the significance effects in the phasic OR were attributable to differences in arousal. The results are discussed in the context of theoretical accounts of the OR.     

Stimulus significance effects in habituation of the phasic and tonic orienting reflex

Phasic and tonic measures of electrodermal activity were examined in a simple habituation paradigm, using innocuous visual stimuli. Separate groups were used to investigate the effects of stimulus significance, as manipulated by instructions. One group had no stimulus-related task (indifferent group), while the other was asked to silently count the stimuli to report to the experimenter later (significant group). Prestimulus skin conductance levels were considered as measures of the arousal level at each stimulus presentation, and the subsequent electrodermal responses were taken as the phasic orienting reflex (OR) elicited by each stimulus. Changes in prestimulus arousal were taken as measures of the tonic OR to the experimental series. Marked group differences were found in both phasic and tonic components of the OR. Some, but not all, of the significance effects in the phasic OR were attributable to differences in arousal. The results are discussed in the context of theoretical accounts of the OR.     

Self-focused attention,facial behavior,autonomic arousal and the experience of emotion

Two experiments examined alternative explanations for the Scheier and Carver(1977) results linking self-focused attention to increased responsivity to emotional stimuli. In both studies autonomic, expressive, and self-report measures of emotional arousal failed to confirm the earlier findings. An individual difference measure reported by others to parallel the effects of situationally manipulated self-attention also failed to confirm the previously reported findings. Though in direct contradiction to Scheier and Carver's results, the results are consistent with a facial feedback hypothesis and with previous findings on the effects of expressive inhibition on self-reports of emotional arousal.This research was supported in part by NSF grant 77-08926 to the first author and by NIMH grant MH 29446 to the third author, as well as by funds from the Lincoln Filene Endowment to Dartmouth College.     

Physiological correlates of conduct problems and anxiety in hyperactive and learning-disabled children

Thirtysix learning disabled children (21 of whom were also classified as hyperactive) were subgrouped according to teacher ratings of tension-anxiety and conduct problems and then compared on measures of tonic and phasic autonomic arousal. The results indicated that children rated high on the conduct problem dimension evidenced smaller amplitude specific skin conductance responses, and that anxiety appeared to exert a moderating effect on physiological responses. When the hyperactive sample was considered separately, lower skin conductance levels were observed in children rated high on conduct problems than in hyperactive children rated low in conduct problems. These findings support the notion that hyperactive and learning-disabled children are heterogeneous at a physiological level and suggest that physiological differences previously attributed to hyperactivity may actually be correlates of the conduct problem dimension.     

Contextual stimulus control of conditional vasomotor and electrodermal reactions to angry and friendly faces

An experiment with 42 human Ss used the transswitching procedure to examine tonic stimulus control of phasic and tonic conditioned vasomotor heart rate, and electrodermal reactions. The conditional stimulus (CSs) were photos of angry and friendly human faces, and the unconditional stimulus (US) was a human scream. In one tonic context (blue light), the CSs were paired with the US, in the other context (yellow light), the CSs were presented unpaired. Following acquisition, an extinction series was run with the US omitted during both tonic contexts. Phasic vasomotor and skin conductance reactions differed in the positive and negative tonic segments (stronger in positive). The skin conductance responses also differed during extinction, but the vasomotor responses did not. Tonic differences (following onset of the tonic stimuli) in unelicited skin conductance response frequency, finger pulse volume, and heart rate were also found, although these developed more slowly than the phasic differences. The finger pulse volume tonic difference was greater in extinction than the skin conductance response frequency. There was no effect of the angry-friendly facial expressions, either directly or in interaction with the transswitching effects. The results were interpreted to mean that the transswitching phenomenon is not limited to one another autonomic effector, but is more generalized across the ANS (sympathetic branch). The absence of influence of the facial expressions indicates the relative weakness of the “preparedness” hypothesis in comparison with more influential contextual factors.     

Exploring the mechanism of dishabituation

In this study we explored elicitation and habituation of the orienting reflex (OR) in the context of indifferent and significant stimuli, particularly aiming to clarify the mechanism driving dishabituation. An in-depth analysis of the mechanisms of electrodermal habituation and dishabituation was conducted, focusing on the role of state measures as determinants of the phasic response profile. Twenty-four young adult participants completed an auditory dishabituation task while electrodermal activity was recorded. Participants listened to a series of 10 innocuous tones of the same frequency (standards), followed by a deviant tone of a different frequency, and succeeded by 2-4 tones of the same frequency as the initial 10 stimuli. All stimuli had a random stimulus onset asynchrony of 5-7 s. Participants completed an indifferent condition in which there was no task in relation to the stimuli, and a significant condition where instruction was given to count the stimuli silently; order was counterbalanced between participants. As predicted, both skin conductance responses (SCRs) and skin conductance levels (SCLs) were larger for the significant than the indifferent condition. The initial phasic ORs were dependent on pre-stimulus arousal level, and there were significant decreases in both SCR and SCL over the first 10 standards in both conditions. Phasic response recovery was apparent to the deviant stimulus, and dishabituation to the following standard stimulus; both effects were enhanced in the significant condition. Sensitisation was apparent in SCL following the initial and deviant stimuli, but the extent of this was confounded with incomplete resolution of the preceding phasic OR in the significant condition. In the indifferent condition, dishabituation was independent of deviant-related sensitisation; this could not be tested in the significant condition. These findings suggest that dishabituation is not a process of sensitisation, but rather, a disruption of the habituation process.     

Tomboys and sissies: Androgynous children?

Psychological studies of masculinity-femininity in children have paralleled those done with adults, which often consider deviations from masculinity for males and femininity for females as abnormal and perhaps pathological. Children who demonstrate cross-sex behaviors, however, may become androgynous adults whose cross-sex behaviors mean flexibility, not pathology. This study had two purposes: (1) to identify potentially androgynous children as those labeled by their peers as tomboys and sissies; (2) to compare personality characteristics of androgynous children with those of peers. Subjects were 312 elementary school children in a midwestern city. Results indicate that the labels tomboy and sissy are not necessarily indicators of androgynous children, but important social behaviors are related to the labels. For males, the possibility of frustrated creativity was raised.     

Multicultural Women's Experience of Household Labor, Conflicts, and Equity

This study examines a group of 419 multicultural women (64 African Americans, 136 Asian Americans, 171 Hispanic Americans, and 48 Middle Eastern Americans) from Southern California. It examines Chafetz's thesis that women with macrolevel power (high socioeconomic status, SES) will show higher levels of conflict with their spouses over household labor. Such conflict is expected to relate to dissatisfaction with the division of household labor as well as time or task differences with spouses over housework. The multicultural women in this study differed among themselves by SES (proportional income, job status, and education) as well as by the household time and tasks with their spouses, but such factors did not influence conflict. Results indicate that regardless of ethnicity or macrolevel power, multicultural women who perform more household tasks than other women are more dissatisfied with the division of labor. These variables alone influence the number of conflicts per week reported by racial and ethnic couples. When reasons for conflict are compared, the equity issue of unfair share is cited more frequently than any others. In general, comparisons with one's spouse on traditional woman's tasks and time on women's work are not salient to the experience of household labor conflicts among multicultural women even when macrolevel power is attained. The majority of our respondents earn 39% of the household income and work for pay 30 hr/week, yet perform the majority of necessary household labor. The proportional income and overall education levels of this sample are similar to Census Bureau statistics for their respective U.S. groups in 1995–1996.     

A review of psychophysiological research with hyperkinetic children

A number of studies have appeared which focus on the issue of whether hyperactive children are psychophysiologically different from normal children and what impact the stimulant drugs may have on psychophysiological characteristics of these children. The present paper reviews these studies under the type of measures that were employed. In general, the results suggest that hyperactive children are probably not under- or overaroused in their resting levels of autonomic functions, although some children may display resting cortical underarousal. However, the findings of studies on the impact of stimulation on autonomic or central functions intimate that some hyperactive children are probably underreactive to environmental stimulation, or are "underarousable." Indeed, where differences between hyperactive and normal children are found in such evoked-response studies, they are consistently in this direction of "underarousability." Results for the effects of stimulant drugs suggest that these drugs energize or increase the "arousal" of these children and enhance the impact of stimulation on the nervous system. The implications of these results for current theories of hyperactivity and for future research are discussed.     

Physiological arousal of obese persons to food stimuli

Physiological arousal was measured in 20 obese and 20 normal-weight subjects during presentation of imagery tasks with food- and nonfood-related stimuli and during presentation and eating of food. No differential arousal, as measured by skin conductance, was obtained between the groups for any of the stimuli. Presentation and eating of the food did produce significant arousal in subjects.     

Reliability issues in the penile assessment of incarcerants

Although there has been increased reliance upon the direct physiological measurement of penile tumescence in the assessment of sexual deviations, the reliability of these measures has never been empirically validated. This investigation evaluates the reliability of the rape index as a technique in differentiating rapists from nonrapists. Eighteen individuals incarcerated on non-sexual-related offenses were presented visual and audio stimuli depicting mutually consenting intercourse, rape, and aggression. These stimuli were presented under two instructional sets: (1) enchance arousal and (2) suppress arousal. Reliability indices for the rape index were computed among various conditions of modality presentation, instructional set, and test-retest conditions. The overall reliability of the rape index was found to be low. The implications of these results upon the assessment and classification of offenders is discussed.     

Physiologic and motor conditioning and generalization in children with minimal brain dysfunction

Twenty-six children diagnosed as having minimal brain dysfunctions (MBD) were compared with 26 controls in a conditinoing and generalization procedure. Skin resistance, heart rate, and muscle action potentials were monitored throughout. Success involved learning which of two tones signalled the accessibility of a penny. Whereas 92 per cent of controls reached the criterion of five successive correct responses, only 62 per cent of MBD’s did. Further, a third of the MBD’s were so maladaptive as to force procedural variations, while only a few minor irregularities occurred with the controls. Quality of performance was related to age, intelligence, and ability to discriminate and remember tones. Controls were more physiologically reactive than MBD’s, especially in skin resistance. Physiologic differentiation of the two tones was significant in both groups of children and appeared concurrently with motor differentiation. The only evidence of physiologic generalization was in the SR data of controls. The possibility that defective arousal structures, or defective coupling of arousal structures and other perceptual and motor structures, could account for the decreased physiologic reactivity, short attention spans, and poor concentration ofsome MBD’s is discussed. This research, in conformity with other laboratory studies of the brain, indicates that motivational as well as cognitive defects may be organically based.     

Arousal and the Relationship Between Positive and Negative Affect: An Analysis of the Data of Ito,Cacioppo, and Lang (1998)

Research on positive and negative emotional states has supported several models of how those states relate to each other. Many studies suggest that they are independent, the bivariate view, while others suggest that they are inversely correlated, the bipolar view. Other research has shown that stress is a major moderator of the relationship; the affects become coupled under conditions of high stress, a contextual model, but are relatively independent otherwise. To expand the range of tests of this dynamic model of affect, we reanalyzed a data set initially reported by Ito, Cacioppo, and Lang (1998) on affect-eliciting picture stimuli. In that study, arousal was assessed separately from positive and negative affect, allowing investigation of a source of interaffect relationships different from stress, per se. Arousal interacted with positive and negative affect, showing both bivariate and bipolar relationships, and effects similar to stress. Affective reactions to the stimuli became more inversely correlated when the affects were high and interacting with higher arousal. The data supported the dynamic model of affect and suggest the need for further analyses of the linkages between stress, arousal, and reduced levels of emotional complexity.     

Context and strategy in acquiring temporal connectives

There has been considerable debate over the role of comprehension strategies in the acquisition of temporal connectives. This study examined the role of caluse logic and interpretational strategies in the acquisition of temporal words; age-related changes were also considered. Thirty-two children between 3 and 5 years of age served as subjects. Sentences with a variety of temporal words were used to tap children's comprehension of before, after, when, while, just before that, and and after that. Clause logic was found to significantly improve the understanding of these sentences. However, the order of mention and main clause first strategies were used infrequently. Apparently, when children respond to sentences that describe information in a way that is consistent with that they normally hear, these strategies are seldom applied.I wish to express my thanks to Janice Bogen, who assisted in data collection, and to Erika Hoff-Ginsberg, who assisted in some of the data analysis.     

Tracking arousal state and mind wandering with pupillometry

In four experiments, the association between arousal state and different mind-wandering states was examined. Participants performed a sustained attention task while pupil responses were continuously recorded. Periodically during the task, participants were presented with thought probes to determine if they were on task or mind wandering. Across the four experiments, the results suggested that in situations that promoted on-task behaviors and focused external attention, mind wandering was associated with lowered arousal, as seen by smaller tonic pupil diameters and smaller phasic pupillary responses. However, in situations that promoted a more internal focus of attention, there were no differences between on-task states and mind wandering in tonic pupil diameter (although differences emerged for phasic pupillary responses), suggesting similar arousal levels. Furthermore, across the four experiments, mind blanking and mind wandering dissociated in terms of whether the situation promoted focused external attention or focused internal attention. These results are broadly consistent with the notion that mind wandering is a heterogeneous construct, with different forms of mind wandering being associated with different arousal states, and suggest that a combination of behavioral and pupillary measures can be used to track these various states.     

Arousal-reducing effects of chronic stimulant use

A variety of studies withhabitual users of nicotine, caffeine, cocaine, and amphetamines have shown that administration of these stimulants has the paradoxical effect of lowering arousal states. Research on transmarginal inhibition shows that when subjects are presented with a succession of stimuli monotonically increasing in intensity, GSR and related arousal responses increase first and then begin to decline beyond a certain point of stimulus intensity. That is, following repeated exposure to intense stimuli, continued more intense stimulation has the effect of lowering arousal. Since stimulants subjectively heighten stimulus intensity, the transmarginal inhibition data provide a basis for explaining opposing effects of stimulants on arousal, depending on dose and frequency of use. It was hypothesized that when dose levels are low and usage is infrequent, arousal increases with stimulant intake. In contrast, when dose levels are high and frequent, arousal shows decrements with new intakes of stimulant. A new questionnaire measure of characteristic arousal was developed and correlated with subjects' reports of habitual levels of stimulant and sedative intake. Weekly total stimulant use correlated significantly and negatively with characteristic arousal level, providing support for the hypothesis. This lowered arousal of frequent stimulant users was not a confound of, or due to, concomitant frequent sedative use, since total stimulant and sedative use levels were uncorrelated.The author would like to thank Janice Schafrik for running the subjects in this study.     

Methylphenidate in hyperactive children: Differential effects of dose on academic,learning, and social behavior

Methylphenidate (Ritalin) has been shown to have differential effects on hyperactive children's behavior as a function of dose level. In the present investigation, a triple-blind, placebo-control, within-subject (crossover) experimental design was employed in which 12 hyperactive boys between 6 and 10 years received three different dosages of methylphenidate (5, 10, and 15 mg) in a randomly assigned sequence. Dosage effects were assessed on clinic(PAL-Paired Associates Learning test) and school-(percent on task, teacher ratings, work completion rates, and accuracy) related behaviors. For 10 of the children, classified as responders to medication by the PAL using the criteria of Swanson, Kinsbourne, and colleagues, a series of ANCOVAs with repeated measures showed significant dosage effects on teacher ratings (p 01), percent on task (p 01), academic accuracy (p 05), and assignment completion rates (p 05). PAL performance was also significantly enhanced (p 01) after optimal dose levels were considered. Subsequent trend analysis showed a significant positive linear relationship between dose and each of the dependent variables. A comparison of fixed-dose and miligram-per-kilogram plots showed that children's performance across the different dosages were clearly individualistic and task-specific, even when similar body weights were compared. The implications of using clinic-based testing to determine optimal medication responsivity were discussed.We would like to express our sincere appreciation to the following pediatricians for their valuable assistance: W. H. McDermott, D. J. Chronley, R. B. Trivett, F. J. Jehle, P. M. Small, and F. T. Leong. Grateful acknowledgement is also extended to the two anonymous reviewers whose comments contributed to the content of this paper, and to the undergraduate and graduate student members of the Children's Learning Clinic.