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At least 19 recordsLinked to original sources
PubMedDate not supplied

Analysis of task demands in apraxia.

Several task demands were examined in a battery of praxis tests: the movement system (limb versus axial), input modality (command versus imitation), movement complexity (single gestures versus a sequence of gestures), type of limb gesture (transitive versus intransitive), and the representational nature of the gestures. Performance accuracy for a group of left hemisphere patients was significantly lower than for two other groups of patients with either right hemisphere damage or no brain damage on all gestures. The right hemisphere patients were significantly different from the normals only for the most complex gestures involving a three movement sequence. Within the left hemisphere group performance to command was not different from imitation. Representational and nonrepresentational gestures were not different, and axial gestures was not different from the limb gestures. The transitive and complex gestures were not different but were both performed less accurately than the intransitive gestures. The implications of these findings for understanding apraxia were discussed.

Analysis of Variance↗
PubMed1976

Effects of stimulus incongruity, task demand, and induced involvement on amplitude of GSR.

Previous investigations into the arousing effects of incongruity have not only reported inconsistent findings but have displayed the limitation of using only two levels of incongruity. An experiment using four levels of incongruity confirmed the hypothesized positive linear function between incongruity and arousal (as measured by GSR amplitude). However, the results of two additional experiments confirmed the hypothesis that the marked arousing effects of incongruity were attributable at least in part to the demands of the task employed which included subjects having to choose and verbally commit themselves to one of the alternatives. The interaction between incongruity and degree of involvement engendered by the task demand suggests that involvement may facilitate the arousing effects of additional collative variables such as novelty, uncertainty, and complexity.

Arousal↗
PubMed1992

Analysis of the effects of task preferences, task demands, and adult attention on child behavior in outpatient and classroom settings.

Two studies were conducted with children who displayed behavior problems to evaluate the effects of task preference, task demands, and adult attention on child behavior. In Study 1, we conducted brief functional analyses in an outpatient clinic to identify variables that facilitated appropriate behavior. For 8 of 10 children, distinct patterns of performance occurred; 3 children displayed improved behavior with changes in task demands, 1 child displayed improved behavior with a preferred task, and 4 children displayed improved behavior with changes in adult attention. In most cases, the children's parents carried out the assessments with adequate procedural integrity. In Study 2, we applied similar assessment methods to a classroom setting over an extended period of time. We identified independent variables controlling appropriate, on-task, and academic behavior for 2 children on two tasks, with slightly different treatment procedures across tasks for both children. In addition, the results of brief functional analyses for both children corresponded to the extended classroom assessments.

Adjustment Disorders↗
PubMed1992

Thematic analysis in agrammatic comprehension: syntactic structures and task demands.

Aphasics' ability to assign thematic roles during sentence comprehension was investigated. The study was motivated by the hypothesis that capacity limitations, e.g., due to slowed processing operations, interact systematically with certain aspects of structural analysis more than with others. Experiments using a sentence-picture matching paradigm were conducted with several agrammatic Broca's and paragrammatic Wernicke's patients. Experiment 1 tested comprehension of various syntatic structures. The astoundingly good performance in Experiment 1 for both patient groups was attributed to the low task demands of the experiment. Raising the task demands, by delaying presentation of the relevant picture set in Experiment 2, resulted in a significant decrement of comprehension performance for agrammatic Broca's aphasics, but not for Wernicke's aphasics. Putting the main verb in the sentence-final position, as in Experiment 3, affected Wernicke's aphasics', but not Broca's aphasics' performance. In principle, one explanation for the performance differences between Experiments 1 and 2 for Broca's patient might be a deficit in these patients' verbal memory capacity. Therefore, verbal memory span on different word categories was tested in an additional experiment. No difference, however, was found between the Broca's patients' and the Wernicke's patients' capacity for verbal memory despite their different sentence comprehension profiles. The present data are taken to support the view that Broca's aphasics' comprehension behavior is due to the processing demands imposed by structural inference chains and not to a general reduction in verbal memory.

Adult↗
PubMed1976

Task demand as reflected in catecholamine excretion and heart rate.

Immediate effects and aftereffects of exposure to a color-word conflict task were studied in two groups of subjects, one of which performed the task without auditory interference ("single conflict"), the other with auditory interference ("double conflict"). Physiological arousal indices were more susceptible than performance measures to the level of task demand. Thus, the higher demand imposed by the double-conflict task was reflected in relatively larger increases of adrenaline excretion and heart rate, both during the conflict task and during the subsequent arithmetic task, whereas the performance measures remained unaffected.

Acoustic Stimulation↗
PubMed1992

Effect of adding cognitively demanding tasks on soccer skill performance.

The effect of adding cognitively demanding elements to the performance of a real-world motor task in which functional interference among the elements in performance existed was investigated across level of expertise. The primary task involved running as quickly as possible through a 15.25-m slalom course. Two secondary tasks were used, dribbling of a soccer ball and identification of geometric shapes projected on a screen located at the end of the slalom course. 4 novice, 5 intermediate, and 5 expert female soccer players served as subjects and performed three trials each of three experimental conditions: running through the slalom course, running through the slalom course while dribbling a soccer ball, and running through the slalom course while dribbling a soccer ball and identifying geometric shapes. Analysis of variance using a 3 (experimental condition) x 3 (level of expertise) design gave significant main effects and a significant interaction. The latter indicated that, although the addition of cognitively demanding elements caused a decrement in performance, the amount of decrement decreased as level of expertise increased. It was concluded that structural interference between elements of performance decreased the positive effect of automation of one element on dual task performance.

Adolescent↗
PubMed1991

Mental rotation of compound stimuli: the effects of task demands, practice, and figural goodness.

Four experiments examined whether or not mental rotation of compound stimuli is a holistic process. Large letters (global aspect) composed of small letters (local aspect) were presented, and the format (normal vs. reflected) of each aspect was manipulated independently. In Experiment 1, the rate of mental rotation was compared under divided- and focused-attention instructions. The overall rate of mental rotation was faster under focused-attention instructions than under divided-attention instructions. Also, contrary to previous findings, in the divided-attention task, the slope of the rotation function was smaller when the stimulus configurations contained aspects with congruent formats (both aspects were normal or mirror-reversed letters) than when they contained aspects with incongruent formats (one normal and one mirror-reversed letter). This pattern of results is unlikely to be caused by the subjects' level of familiarity with the divided-attention task (Experiment 2), by postrotation processes (Experiment 3), or by stimulus attributes (figural goodness) confounded with the format-congruency variable (Experiment 4). The implications of these results for models of mental rotation of compound stimuli are discussed.

Adult↗
PubMed1990

The object-line effect: is it attributable to intercontext differences or the structural properties of contexts and task demands?

Briefly presented target lines are reported more accurately when part of an object-like context than alone (Williams & Weisstein, 1978). Efforts to explain this effect have tended to focus on structural properties that contexts must possess in order to be effective in facilitating target-line discrimination (e.g., Weisstein, Williams, & Harris, 1982). Enns and Prinzmetal (1984) take issue with this approach. They propose that contexts differ more from one another than do target lines presented alone, and it is this fact, and not the general structural properties of contexts, that underlies their effectiveness. Two experiments examined intercontext differences and structural factors as determinants of context effectiveness. Subjects were found to use intercontext differences to narrow the range of possible alternatives, but when this factor was controlled, structural properties determined context effectiveness. The structural interpretation of context effectiveness was found not be as straightforward as generally assumed, however. A third experiment showed context effectiveness to be affected by the character of the discrimination task employed.

Attention↗
PubMed1992

Linguistic performance as a function of abstract task demands in children with spina bifida.

Children with spina bifida and hydrocephalus (SBH) have been observed to have deficits in discourse, characterized by a high frequency of irrelevant utterances and poorer performance with abstract than concrete language. The Preschool Language Assessment Instrument (PLAI) was used to compare children with SBH and language-age controls on discourse skills at four levels of abstraction. In addition, a qualitative assessment of differences in types of inadequate productions was conducted. Children with SBH performed comparably to controls on concrete levels of the PLAI, but they produced significantly more 'no response' and irrelevant responses than the controls.

Attention↗
PubMed1977

Cardiac and respiratory responses during visual search in nonretarded children and retarded adolescents.

The relationship between physiological response patterns and mental competence was investigated by evaluating heart rate and respiratory responses during a sustained visual-search task in nonretarded grade school children and retarded adolescents. The findings support the contention that, during tasks demanding sustained attention, retarded relative to nonretarded individuals exhibit physiological responses that parallel their poor performance. Consistent with previous research with nonretarded adults, the nonretarded grade school children exhibited a suppression of respiratory and heart-rate variability during attention-demanding tasks. In contrast, the retarded adolescents exhibited increases in respiratory and heart-rate variability. These qualitative differences in physiological and behavioral responses, observed during sustained attention, may be viewed as a manifestation of retarded adolescents' defective nervous system.

Adolescent↗
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↗
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↗