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PubMed1990

Hemisphere-specific resource demands of task expectancies.

The hemisphere-specific resource demands of expecting letter- and figure-matching tasks were investigated, using dual-task methodology. Matching task expectancies were induced by blocking trials with respect to stimulus type (letters or geometrical figures). On one third of the trials, the matching stimuli were unexpectedly omitted. The secondary task required a speeded reaction to a laterally presented auditory probe. The side of probe presentation was unpredictable. Probe reaction times were taken as an index of the resource demands imposed by the primary task on the contralateral hemisphere. For both the trials with and without matching stimuli, probe reaction times showed a significant interaction between lateral side of probe presentation and block type (letters or figures). When letters were expected, reaction times were slower in the left-hemisphere probe task. Probe reaction times were equally fast for both sides when figures were expected. Overall, these results indicate that task expectancies primarily demand resources from the hemisphere that is specialized for carrying out the expected task.

Adult↗
PubMed1992

Heightened motor activity level in male offspring of substance abusing fathers.

Heightened activity level has been implicated in the liability for substance abuse, but no prior research has directly examined motor activity in a sample of prepubertal boys at high-risk for substance abuse. The magnitude of behavioral activity of 10-12 year-old sons of substance abusing fathers (SA +) (n = 42) and controls (SA -) (n = 60) was assessed using a microprocessor-based activity monitor during tasks that demanded significant concentration, effort, and constraint on motor activity, and when no such demands were present. Psychiatric status, measures of temperament traits, and measures of internalizing and externalizing behaviors were also obtained on the boys. Although the groups did not differ during the lower demand task, SA + boys showed significantly greater motor activity than SA - boys during the tasks that required concerted effort, attention, and behavioral suppression. Multiple regression analysis indicated that under the low-demand condition, the presence of an anxiety disorder in the boy was the only significant predictor of activity level. However, under the conditions that demanded effort, concerted attention and behavioral suppression, SA + group membership, and having low rhythmicity (as a temperament trait) predicted heightened activity. Statistically controlling for rhythmicity, the SA + boys were estimated to have about 24% higher activity than control boys. The results suggest that heightened motor activity may be associated with susceptibility to substance abuse.

Attention↗
PubMed1990

Maternal regulation of children's problem-solving behavior and its impact on children's performance.

This study focused on a social interaction theory of the development of cognitive self-regulation. Specifically, the effect of mother-child interaction on the child's ability to problem solve was investigated. The general predictions were (1) children who interacted with their mothers throughout a problem-solving task would subsequently exhibit improved independent performance over practice-control children, who received corrective feedback from a female experimenter at the end of the task; (2) mothers would be more responsible for task activities, would more often regulate their child's task behaviors, and offer more specific verbal content when task demands on child competence increased than when they decreased. 60 3- and 5-year-olds either worked with their mothers or practiced alone and were given corrective feedback on a sorting task in which miniature pieces of furniture were placed in a doll house. As predicted, children who interacted with their mothers subsequently created more correct, adult-like groupings independently than children who received corrective feedback. Mothers displayed more task responsibility and regulation with younger children and when task demands on children of both age groups increased. Maternal verbal content became less specific when task demands decreased. Child performance was related to (1) variation in maternal regulation of the child; and (2) degree of specificity of maternal verbal content.

Child Development↗
PubMed1991

Basal forebrain cholinergic system: a functional analysis.

This chapter has been organized empirically, focusing on the types of approaches that have been taken to understand BFCS function. This approach reflects the state of our knowledge about the behavioral and psychological functions of the BFCS. Considerable information has been gathered in the very short time that the BFCS has been the object of intense investigation. The results from the neurotoxic lesions and from the HACU studies provide some points of consistency and some puzzling differences. Both approaches to the study of basal forebrain function suggest that the MSA is involved in tasks that require spatial working memory; MSA lesions impaired choice accuracy, and HACU in the HIP was increased after performance. The pattern of results in simpler tasks is more difficult to interpret. In a left-right reference memory discrimination in a T-maze, MSA lesions did not impair acquisition or performance, whereas HACU in the HIP was activated during performance. This pattern of results suggests that although the MSA is engaged during this type of task, its activity is not necessary for normal performance. These, and other comparisons indicate the need for a systematic analysis of task demand (Olton, 1989b). Parametric manipulations of different task demands in a systematic fashion can indicate the extent to which the BFCS is involved in the function associated with each parametric manipulation. Ultimately, of course, the organization of this material should focus on particular psychological functions, rather than the techniques and procedures used to gather the information. Achieving this goal is going to require careful attention to the design of behavioral experiments so that definitive conclusions can be made about the extent to which the BFCS is involved in a given psychological function. A systematic application of task analysis can achieve this goal (Olton, 1986, 1989a, 1989b). For example, BFCS lesions in rats impair choice accuracy in spatial working memory tasks, and performance in these tasks engages the HACU system, at least in the HIP. If the spatial functions of this task involve the BFCS, then a nonspatial version of the task should produce a different pattern of results. If the spatial nature of the task is unimportant for BFCS function, then a nonspatial version of the task should produce the same results. By systematically changing one characteristic of the task at a time, the contribution of each component can be assessed.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗
PubMedDate not supplied

The dual nature of lateral eye movements.

This study investigated the validity of lateral eye movements (LEM) as a measure of the individual differences and task demands aspects of LEM by comparing eye movements to information questions that had no clear hemispheric locus with eye movements to rhyme questions that demanded specific left hemisphere involvement. Fifty subjects were asked to respond to the two types of questions and the initial direction of their eye movement was recorded. The results indicated that LEM are a reliable measure of individual differences because both test-retest and split half reliabilities were high (.78 to .85). LEM were also shown to be responsive to task demands. The number of leftward LEM did not differ from rhyme and information questions, but there were more rightward LEM and fewer stares to the rhyme question. These results suggest that LEM are a reliable individual difference measure and are sensitive to task differences. There is clear evidence that LEM have neuropsychological implications, but every task demands the integrated functioning of the whole brain and these implications should not be overgeneralized.

Adolescent↗
PubMed2026

Response-optimised training improves learning of a complex motor task and closely related motor tasks.

Regular physical exercise is essential for promoting healthy aging and longevity. In older adults with varying physical and cognitive decline, optimising exercise interventions is crucial to maximise benefits. A promising approach to achieve this goal is by adjusting task demands to individual abilities in turn preventing over- or underloading their abilities. In the field of motor learning, it is currently unclear whether such an optimised training improves not only performance on the trained task but also transfers to untrained motor and cognitive tasks. We conducted a randomized, single-blinded, 6-week dynamic balance training (DBT) with healthy older adults (n = 30). Training was tailored to individual balance ability. Participants were assigned to either suboptimal (high or low difficulty) or optimal (moderate difficulty) training groups. Transfer effects were assessed via cognitive tasks (memory and executive) and motor tasks (untrained DBT variations and other balance tasks) measured pre-, mid- and post-intervention. Multivariate longitudinal statistical analysis showed higher performance gains in the optimal training group in three out of six sessions compared to the suboptimal groups, especially under testing conditions with high task demands. The optimal group also showed greater improvements in near motor transfer tasks mid- and post-intervention, while no significant differences were observed in the cognitive tasks. Within-group DBT learning positively correlated with transfer gains, highlighting the role of training response in achieving transfer. In conclusion, optimised task difficulty in balance training enhances both task-specific performance and related motor skills, supporting the use of personalised interventions to maintain function and independence in older adults.

Humans↗
PubMed1990

Concurrent cognitive processing and letter sequence transcription deficits in stutterers.

Previous research has indicated that men who stutter transcribe rapidly presented sequences of letters more slowly and less accurately than nonstutterer controls. Experiment 1 demonstrated that the transcription deficit is not limited to task conditions that demand concurrent monitoring and responding. This was evidenced by comparable deficits on a successive response condition that required subjects to write letters after the presentation was complete. The results of Experiment 2 indicated that the deficit is not due to a difficulty by stutterers in parsing streams of stimulus information internally. Their performance did not differentially improve when letters were grouped with brief pauses, nor with experience in transcribing preparsed letter sequences. This experiment also demonstrated that the phenomenon is generalizable to women. In related testing, stutterers were slower than controls in writing internally generated sequences of letters, those of the alphabet forwards and backwards, but not in writing the same two letters, A and B, repetitively nor in the cognitively more demanding task of writing numbers backwards by three's. These results parallel those obtained with finger tapping of same versus unique sequences by stutterers and were interpreted as being consistent with the idea that while stutterers are not generally slower motorically than nonstutterers, they experience difficulty when required to organize and carry out tasks with new multiple response transitions. The two experiments have replicated and extended, under different conditions, the earlier findings of a letter sequence transcription deficit in stutterers, but the nature of the interference still remains to be clarified.

Adolescent↗
PubMed1990

Hemodynamics of blood pressure responses during active and passive coping.

This laboratory study was designed to address a number of interrelated issues regarding cardiovascular reactivity to psychological stress. One objective was to extend the previous research comparing cardiovascular responses during active versus passive coping, by comparing responses to two task conditions designed to be similar in all ways except the opportunity to make a response influencing the task's outcome. A second objective was to compare responses to two different passive film tasks, which differed in outcome uncertainty and the degree of vicarious active coping achieved through identification with the role portrayed by the actors. A third objective was to evaluate whether individuals are predisposed to exhibit a particular hemodynamic pattern underlying their blood pressure adjustments, independently of the task demands imposed. Ninety healthy young adult male subjects were tested in pairs on a series of tasks that included a competitive reaction-time task, an active as well as a passive phase of a team reaction-time task, and passive viewing of two film segments. The tasks demanding active coping responses tended to raise blood pressure due primarily to an increase in cardiac output, while vascular resistance fell. During passive coping demands cardiac output increased to a lesser extent, but vascular resistance also tended to increase, thereby raising blood pressure by their synergistic effects. However, these patterns were not typical of all participating subjects. On the basis of their cardiac output and vascular resistance responses to the competitive reaction-time task, one third of the subjects were categorized as being high myocardial reactors (n = 30) and another third high vascular reactors (n = 31). Post-hoc analyses of responses to the other tasks, based on these categorizations, indicated that the hemodynamic basis of reactivity is an individual characteristic only partially modified by coping demands. The active/passive coping dimension is discussed both conceptually and in relation to the role of stress in the etiology of hypertension.

Adaptation, Psychological↗
PubMed2026

Dual-tasking reveals severity-dependent reorganization of cortical beta energy landscapes in Parkinson's disease.

Dual-task impairment is a hallmark of Parkinson's disease (PD), yet the large-scale neural mechanisms underlying postural-motor interference remain poorly understood. In particular, it is unclear how cortical network dynamics reorganize across disease severity when postural control competes with concurrent task demands. This study investigated EEG-derived beta-band cortical energy landscapes in healthy older adults, early-stage PD, and mid-stage PD during single- and dual-task conditions. Dual-task behavioral cost increased with disease severity for concurrent manual performance (p&#xa0;<&#xa0;0.001), whereas a quadratic pattern was observed for postural performance. Energy landscape analysis revealed severity-dependent reconfiguration of cortical beta dynamics. Dual-task-related landscape changes in effective network flexibility (&#x394;Neff), landscape geometry (&#x394;Evar and &#x394;Gmag), and dominant low-energy attractor organization (&#x394;Low mass and &#x394;Low area) showed significant monotonic trends (p&#xa0;<&#xa0;0.05), reflecting progressive constrained cortical network dynamics with advancing PD severity. In addition, dual-task-related landscape alterations were associated with clinical severity, as indexed by Hoehn and Yahr stage (|r|&#xa0;=&#xa0;0.353-0.423, p&#xa0;=&#xa0;0.016-0.048), and showed associations with motor impairment, as measured by MDS-UPDRS part III scores (|r|&#xa0;=&#xa0;0.333-0.455, p&#xa0;=&#xa0;0.009-0.063). These findings demonstrate that dual-task demands induce severity-dependent reconfiguration of cortical beta energy landscapes in PD. Energy landscape geometry may capture systems-level neural constraints associated with dual-task susceptibility in PD, providing a physiologically grounded framework to characterize disease-related functional vulnerability.

Humans↗
PubMed1990

Performance of concurrent non-motor tasks in Parkinson's disease.

The purpose of the study was to examine the hypothesis that patients with Parkinson's disease have a general inability to cope with concurrent task demands, and that this inability stems from a lack of attentional control of motor and cognitive activities. Performance on a verbal and on a visuospatial memory task was compared with performance on largely identical memory tasks which were combined with concurrent non-motor tasks. As a further index of a possible weakness of the attentional control of cognitive function order memory was assessed and compared with item memory. Both parkinsonian patients and controls showed a decline of memory performance when the concurrent task was introduced, but the degree of decline did not differ between groups. Parkinsonian patients scored worse than controls on both conditions of the verbal memory task and had more intrusions from previous lists in the verbal single task. There was no significant difference between groups in either item or order memory, but in parkinsonians the scores on order memory decreased with advancing illness. It is concluded that patients with Parkinson's disease do not have a general inability to cope with concurrent task demands, but that the results can be interpreted as indicating a weakness of certain aspects of the attentional control of cognitive function.

Analysis of Variance↗
PubMed1992

Manipulation of visual mental images in children and adults.

Recently, there has been a debate on whether visual patterns can be transformed and reinterpreted in mental imagery. In the present study, task demands and age of subjects were manipulated to see whether children and adults were able to discover a novel visual pattern after transforming a mental image. Two tasks, called combination and subtraction, were devised. They consist of either compounding or taking away parts of images to discover a new construal. Results indicate that not only adults, but also children aged 6 and 10, are able to transform a mental image so as to yield another image with a different interpretation. Task demands had a greater effect on children than adults, consistent with the suggestion that the ease of manipulating mental images is a function of the efficiency of control processes.

Adult↗
PubMed1990

Family caregivers and limitations in social activities.

Constriction of social and personal activities is one of the most frequently noted consequences of caring for a frail elder. This study analyzed the correlates of perceived limitations in social activities using data from a national sample of the frail elderly and their caregivers. Two research issues were addressed: 1) What differences in demographic, family, and caregiving attributes are associated with variation in perceived restricted social activities? and, 2) How does the process influencing restriction of social activities vary by family relationship of the caregiver? Higher levels of elder dependency and task demands were characteristic of those who reported social limitations, and daughters and wives were more likely to report such limitations than sons and husbands. Subjective assessment of time and task demands, however, were more important influences than objective caregiving activities for all family caregivers.

Aged↗
PubMed1990

Asymmetries in hand movement during block design construction.

Changes in patterns of hand use were examined as a function of task demand characteristics. Using blocks, right- and left-handed male and female subjects were asked to simultaneously construct two replicas of presented patterns, one with each hand. With the presentation of visual-spatial patterns, a shift toward use of the left hand from baseline was observed. This change was least evident among right-handed females. The observed shift in hand use toward the left on a visuo-constructive block design task might suggest differential involvement of the right hemisphere with changes in task demand characteristics.

Adult↗
PubMed1991

Ecobehavioural analysis of stereotypic and adaptive behaviours: activities as setting events.

The effects of activities and task demands on the rate of stereotypic and adaptive behaviour were analysed within the conceptual framework of setting events. Data on 12 mentally retarded subjects were collected in real time using portable microcomputers during six activities: leisure, pre-vocational training, gym, academic instruction, home living, and lunch. Results showed that stereotypic and adaptive responses occurred in all settings, with the two behaviours occurring simultaneously across both subjects and activities some of the time. Micro-level analysis showed that teacher covert task demand provided the setting event for most of the stereotypic and adaptive responding during each activity. The importance of ecobehavioural analysis in understanding the nature of stereotypy and adaptive behaviour, and the contribution of such an analysis to appropriate and effective intervention were highlighted.

Adaptation, Psychological↗
PubMed1975

Cortical evoked potentials elicited by real speech words and human sounds.

Averaged evoked potentials were recorded from PZ and left and right temporo-parietal electodes to real speech words and human sounds in 8 right-handed subjects. Stimuli were presented in a "no task" condition where the subject was instructed to listen attentively, and a vigilance condition where the subject responded to a particular word or sound during a run of such stimuli. The vigilance condition produced two classes of stimuli:signals and non-signals. Evoked potentials to physically identical words or sounds were examined when they were "no task", non-signal and signal stimuli. P300 amplitude increased significantly as a function of increasing task demands going from "no task" to non-signal to signal. When a strict statistical criterion for multiple comparisons (Bonferroni test) was applied in looking for asymmetries between hemispheres, only 2 isolated left greater than right differences turned out to be significant. Review of the literature concerning evoked potential correlates of differential hemispheric processing pointed up flaws in design, statistical technique, and inconsistencies in reported findings which suggested that while evoked potentials may sometimes reflect differences in hemispheric functioning, this effect is marginal at best.

Adult↗
PubMed1990

Schizophrenic performance on line bisection: no simple lateralization defects.

Many studies have assessed the possible lateralization deficits of schizophrenics, and the results usually suggest left hemisphere dysfunction. Nevertheless, they have been variable. This may have been due to cognitive demand of the different tasks, not to changes in brain lateralization itself. In order to circumvent this problem, the present study evaluates the performance of schizophrenics on a simple but lateralized task, line bisection. Subjects bisected a line using either visual or tactile information, with the left or right hand, when it was placed in their left or right hemispace or directly in front of them. Schizophrenic subjects were not more erroneous than normals (variable error), nor were they biased differently from normals in either direction with either modality of sensory input (constant error). There were only two significant effects of group on the tactile line bisection, one of position x length x group and one of position x hand x end x length x group, both on constant error (directional bias). The lack of main effects and presence of interactions on these basic tasks suggests that apparent lateralization differences found in schizophrenic subjects are due not to a simple defect of brain lateralization but may stem from task demands and attention allocation.

Attention↗
PubMed2026

The asymmetry of working memory training transfer: A systematic review and meta-analysis.

Working memory (WM) training is widely used to enhance cognitive performance; however, its transfer to untrained tasks remains controversial. Traditional theories emphasize task similarity as the primary determinant of training transfer, but they cannot fully explain emerging evidence of asymmetric transfer across tasks. Two directional transfer hypotheses are proposed here to explain this asymmetry: the resource-based transfer advantage hypothesis predicts stronger transfer from more to less cognitively demanding tasks, whereas the ability-based transfer advantage hypothesis predicts stronger transfer from tasks engaging broader task-general abilities to tasks engaging task-specific narrower abilities. The contrast between span and updating paradigms provides an informative framework for distinguishing these accounts, because updating tasks are generally more cognitively demanding, whereas span tasks involve broader abilities. Accordingly, we conducted a three-level meta-analysis of 55 studies (208 effect sizes; N = 3,492). The results showed that updating training transferred reliably to span tasks (g = 0.176, p < .001), whereas span training did not reliably transfer to updating tasks (g = 0.048, p = .453), supporting the resource-based account. This advantage of updating training also extended to non-WM outcomes and was more pronounced at lower training doses, in non-adult samples, and with verbal stimuli. Together, these findings extend WM transfer theory beyond task similarity by highlighting the importance of cognitive demand and offer guidance for WM training design.

Humans↗