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Temporal coordination of the human head and eye during a natural sequential tapping task.

The 'natural' temporal coordination of head and eye was examined as four subjects tapped a sequence of targets arranged in 3D on a worktable in front of them. The head started to move before the eye 48% of the time. Both the head and eye started to move 'simultaneously' (within 8 ms of each other) 37% of the time. The eye started to move before the eye only 15% of the time. Gaze-shifts required to perform the tapping task were relatively large, 68% of them were between 27 degrees and 57 degrees. Gaze-shifts were symmetrical. There were almost as many lefts as rights. Very little inter- or intra-subject variability was observed. These results were not expected on the basis of prior studies of head/eye coordination performed under less natural conditions. They also were not expected given the results of two rather similar, relatively natural, prior experiments. We conclude that more observations under natural conditions will have to be made before we understand why, when and how human beings coordinate head and eyes as they perform everyday tasks in the work-a-day world.

Eye Movements↗

A clockwork nursing unit. Analyzing how nurses spend their time is the first step toward improving productivity.

Until recently, productivity analysis has been a relatively underdeveloped tool in nursing. As healthcare costs continue their upward spiral, however, managers have been pressured to measure and evaluate nursing productivity. The right combination of efficiency and effectiveness is the key to optimal productivity. Nursing can be efficient but highly ineffective and thus of little value to the patient; conversely, nursing can be effective and valuable, but grossly inefficient. To determine a nursing unit's level of productivity, managers can keep a daily record of the number of nursing hours per patient day. When the record indicates too many ineffective or inefficient days, an analysis of how nurses use their time can help solve the problem. The first step is such an analysis is to have management engineering or the nursing staff itself collect data on time spent per task. Once these data are collected, they can be analyzed by shift (for the entire hospital), by individual unit, by task category, etc. With this information in view, managers can ask key questions to help pinpoint areas where efficiency might be improved.

Arizona↗

Executive control of cognitive processes in task switching.

In 4 experiments, participants alternated between different tasks or performed the same task repeatedly. The tasks for 2 of the experiments required responding to geometric objects in terms of alternative classification rules, and the tasks for the other 2 experiments required solving arithmetic problems in terms of alternative numerical operations. Performance was measured as a function of whether the tasks were familiar or unfamiliar, the rules were simple or complex, and visual cues were present or absent about which tasks should be performed. Task alternation yielded switching-time costs that increased with rule complexity but decreased with task cuing. These factor effects were additive, supporting a model of executive control that has goal-shifting and rule-activation stages for task switching. It appears that rule activation takes more time for switching from familiar to unfamiliar tasks than for switching in the opposite direction.

Cognition↗

Flexibility, inhibition, and planning: frontal dysfunctioning in schizophrenia.

Neuropsychological tests known to reveal abnormalities in patients with frontal lobe damage were used to explore cognitive function in 20 chronic schizophrenic patients. Eleven control subjects, matched on age and NLV-IQ (NLV is the Dutch version of the NART) were also tested. No impairments of planning ability were found on either the Action Program test or the Zoomap test, both subtests from the BADS (Behavioural Assessment of the Dysexecutive Syndrome). No abnormalities were apparent on tests of reactive flexibility, measured by task-switching and by the Rule Shift Cards test, also a subtest of the BADS. Patients with schizophrenia, however, had significantly greater difficulty in inhibiting irrelevant information and in generating words in a verbal fluency task, a measure of spontaneous flexibility.

Adult↗

Ergonomic aspects of sport and recreation.

Human factors engineering or ergonomics originated in military technology from the team-work of engineers and specialists in the human sciences. The central focus is on the human operator upon whom the task and environment impose specific loadings. Intransigence of task demands in sport tends to shift emphasis to training and selection. Heredity seems to play the more important role in the evolution of the champion athlete. An integrated interdisciplinary approach is advocated in assessing task demands and individual capacity to meet them. Improving equipment and facility design promotes safety and performance efficiency. Environmental stresses may be simulated in laboratory conditions to provide opportunity for prior adaptation. Stresses associated with urbanized civilization present novel risks to social health. Quality of life can be enhanced from an ergonomics input into the design of sports facilities and exercise programmes and their subsequent monitoring.

Aerobiosis↗

Effects of alternating 8- and 12-hour shifts on sleep, sleepiness, physical effort and performance.

OBJECTIVES: The aim of the present study was to compare 12-hour shifts during weekends with 8-hour shifts during weekdays with respect to sleep, sleepiness, physical effort, and performance. METHODS: Thirty-one subjects at a power plant participated. Sleep, sleepiness, and physical effort were measured with a diary. About half of the subjects carried out a reaction-time test during both 8- and 12-hour morning and night shifts. The remaining subjects carried out a vigilance task. RESULTS: Sleepiness was higher and physical effort lower on the 12-hour night shift than on the 8-hour night shift. However, the subjects who had the same level of physical effort on 8- and 12-hour night shifts did not differ with respect to sleepiness. During the 12-hour morning shift, sleepiness was lower and the sleep length was longer than on the 8-h morning shift. The subjects who had the same amount of sleep for 8- and 12-hour morning shifts showed no difference in sleepiness. Sleep did not differ between 8- and 12-hour night shifts. There was no difference between 8- and 12-hour shifts with respect to performance. CONCLUSIONS: It was suggested that the difference in sleepiness between 8- and 12-hour shifts is related to differences in sleep length for the morning shift, and to differences in physical effort for the night shift, rather than to shift duration. Thus the most likely conclusion is that 12-hour shifts do not cause increased sleepiness or impaired performance or disturbed sleep.

Adult↗

A multidimensional evaluation of fire fighter training for hazardous materials response: first results from the IAFF Program.

The International Association of Fire Fighters (IAFF) course on hazardous materials training for first responders is described together with an evaluation plan that includes multiple levels of assessment. Trainee appraisals of the course, shifts in their ratings of task competencies, gains in knowledge quiz scores, and self-reports on actions reflecting lessons learned from the course are among the measures used. Evaluations of courses given in several city fire departments found more than 60% of trainee judgments of course quality and utility to be highly favorable, along with significant post-course improvements in their competency ratings and quiz scores. Follow-up interviews with samples of trainees also suggested more self-protective behaviors and preventive actions being taken with regard to alarms and risks of hazardous materials exposures. However, cross-comparing the results for the various evaluation measures gave only limited support to a popular evaluation model that hypothesized that they would be interdependent. Limitations in appreciating technical course subjects, the value of add-on or refresher instruction, and variable risk experiences are noted in explaining differences in some training results.

Analysis of Variance↗

Attentional bias associated with alcohol cues: differences between heavy and occasional social drinkers.

RATIONALE: Previous research has shown an attentional bias toward drug-related stimuli in opiate addicts and toward emotionally threatening words in anxiety patients. OBJECTIVE: The primary aim of this study was to investigate whether non-dependent heavy social drinkers would differ in their selective attention towards alcohol-related stimuli in comparison with a group of occasional social drinkers. METHODS: Attentional bias was assessed using alcohol-related pictures and words in a dot probe detection task. Picture and word pairs were visually presented, followed by a dot probe that replaced one of the items. Attentional bias was determined from latencies in responding to the dot probe. Questionnaires were used to examine the relationships among attention, outcome expectancies after alcohol consumption, and personality traits. Higher-order executive function was also measured with two cognitive tasks, recognition memory and attentional shift. RESULTS: The heavy social drinkers showed an attentional bias towards the alcohol-related stimuli when compared to the occasional social drinkers. The heavy social drinkers also scored more highly on expectancy factors of sociability and sexuality and lower on the personality traits of self-directedness and persistence. CONCLUSION: The results support cognitive theories of addictive behaviour in which the ability of drug-related stimuli to capture attention is suggested to play a part in drug dependence, craving and relapse.

Adolescent↗

A developmental study of covert orienting to peripheral visual cues.

Observers aged 6, 8, and 20 years participated in a speeded classification task designed to measure covert shifts of visual attention. On each trial observers responded to a target which appeared in one of three locations arrayed horizontally across the display. Three prestimulus cues were employed: neutral (the cue was present in all three possible target locations), unpredictable (the cue was present in the target location on a random basis), and predictable (the cue was present in the target location on 80% of the trials). There were four developmental findings: (1) Observers of all ages oriented attention automatically to the cued locations, (2) children processed targets in non-cued locations more slowly than adults, (3) only adults took advantage of the predictability of the cue, and (4) all age groups provided evidence that strategic orienting competes with response priming for cognitive resources. The implications of these findings for theories of attentional development are discussed.

Adult↗

Evoked potential indices of selective hemispheric engagement in affective and phonetic tasks.

Evoked potentials (EPs) to a probe click stimulus were recorded from left and right temporal areas of dextral adults engaged in phonetic and prosodic processing of an emotionally charged tape recorded conversation. Attenuation of the probe EP amplitudes was significantly greater in the left and right hemispheres during the phonetic and prosodic tasks, respectively, indicating lateral dominance shifts depending on selective processing of linguistic vs affective cues conveyed by the same speech signals.

Adult↗

Long-term effects of antidepressants on balance, equilibrium, and postural reflexes.

To assess the long-term effects of antidepressant medication on balance, equilibrium, and postural reflexes, we studied 30 patients, ages 20-76 years, who had a diagnosis of depressive disorder (as defined by DSM-III-R criteria) and had been treated with tricyclic antidepressants (TCAs) or selective serotonin reuptake inhibitors (SSRIs) for > or = 1 year. They were assessed by a Balance Master System. The assessment included three tasks: static balance, rhythmic weight shift, and limits of stability. When compared with 30 nonhospitalized healthy controls (of comparable age and the same sex), patients who took TCAs showed impaired balance function in all main indices. The results suggest that the impairment of balance function includes motor coordination, fine-motor control, postural reflexes, maintaining equilibrium, and reaction time. No obvious impairment of balance function was observed in patients who took SSRIs.

Adult↗

The relationship between employment and neuropsychological impairment in HIV infection.

The relationship between neurocognitive impairment and employment in a cohort of 130 predominantly symptomatic individuals with HIV-1 infection was examined. Participants were classified as employed (full or part-time for pay) or unemployed (N = 64) and administered a neuropsychological test battery. When covarying for CD4 count, age, and physical limitations, the results revealed that unemployed men performed below that of employed participants on tasks of memory, set shifting-cognitive flexibility, and psychomotor speed. The results are discussed within the context of similar findings in other illnesses.

Adult↗

Determination of language dominance: Wada test confirms functional transcranial Doppler sonography.

OBJECTIVE: To determine the efficacy of the invasive Wada test in determining language dominance, and to validate the functional transcranial Doppler sonography (fTCD) examination in patients. BACKGROUND: Previous work shows that simultaneous bilateral fTDC may identify cognitive hemispheric dominance in healthy individuals. METHOD: fTDC and the Wada test were performed prospectively in 14 patients with various diseases (tumors, cerebrovascular events, head injury, intractable epilepsy). fTDC hemispheric dominance was determined based on the hemispheric blood flow velocity shift for language and visuospatial tasks. RESULTS: fTDC was performed easily in patients. One patient could not be examined by fTDC because of absent temporal bone window for ultrasonic transmission. Two Wada tests were inconclusive due to patient somnolence. One of these patients suffered from right frontal tumor and had aphasia remitted under steroids when examined. fTDC indicated a bilateral language dominance. In the remaining 11 patients the correlation between fTDC and Wada language lateralization indices was 0.75 (p = 0.008). If a post hoc cutoff score was taken for the fTDC language lateralization index, in eight patients, both fTDC and Wada testing determined the left hemisphere to be dominant for language; in the other three patients, language function was bilateral in both examinations. CONCLUSION: Although the current results are preliminary and require replication in a larger sample, fTDC seems to be able to assess hemispheric language dominance not only in healthy individuals, but also in patients. It might become an alternative noninvasive or complementary tool to the Wada test, particularly in patients in whom the Wada test is impractical or gives inconclusive results.

Adolescent↗

Relationship between discrimination tasks of the cantab and the corpus callosum morphology in Alzheimer's disease.

The relationship between performances on a simple discrimination task of the Attentional Set Shifting of the Cambridge Neuropsychological Test Auto mated Battery (CANTAB) and morphometry of the corpus callosum is examined in patients with Alzheimer's disease. Analysis showed patients with probable Alzheimer's disease are heterogeneous for the relationship between performances in the attentional test of the CANTAB and the anterior callosal atrophies. Interest in these results for clinical diagnosis of this mental disease is discussed.

Aged↗

Effects of an overnight fluid infusion on cognitive functions in preoperative patients.

The results of the present study show that subjects who received an overnight infusion of isotonic fluid did significantly less well at particular neuropsychological tests than controls who did not receive such an infusion. The relevant test parameters involved aspects of word list learning, and concept shifting on a complex speed task. Potentially biasing factors such as anxiety, disturbed sleep, education and age could be discarded. With respect to the physiological mechanism involved, the results suggest that a relatively expanded extracellular volume without dilutional hyponatremia might underlie the diminished performance. The experimental group did not lose weight overnight, and the hemoglobin and haematocrit level of the experimental group were significantly different from those of the control group; the blood pressure, plasma electrolytes and osmolality were not different. The present results provide evidence that disturbances in fluid homeostasis may affect cognitive performance.

Adult↗

The relationship between serum testosterone and visuomotor learning in hand skill in right-handed young women.

The relationship between serum testosterone level and motor learning in hand skill was studied in right-handed young women. Hand skill was assessed by a peg moving task. Subjects were required to shift 25 pegs from one of two parallel rows to the corresponding holes as fast as possible, first with right and then with left hand. One trial consisted of the time elapsed to move 25 pegs with one hand. Ten trials were performed by each hand. Peg moving times for the right and left hands linearly decreased at each successive trial (visuomotor learning). Subjects were divided into two subgroups as those having serum testosterone concentrations below and above the mean. The right hand skill and its motor learning was found to be better in subjects with low testosterone than those with high testosterone. The left hand skill was better in subjects with low testosterone than those with high testosterone; there was no significant difference in the left-hand learning in subjects with low and high testosterone (parallel regression lines). Motor learning linearly decreased with testosterone for the right hand, not for the left hand. These results seem to be in accord with the testosterone theory of cerebral lateralization (Geschwind & Behan, 1982).

Adolescent↗

Identification of static and dynamic postural instability following traumatic brain injury.

OBJECTIVE: Quantitative evaluation of static and dynamic aspects of postural instability as a long-term consequence of traumatic brain injury (TBI). DESIGN: Experimental two-group design. SETTING: Outpatient rehabilitation department. PATIENTS AND OTHER PARTICIPANTS: From a consecutive sample of TBI patients at least 6 months after trauma, 20 subjects were selected who complained of reduced gross motor skills but showed no sensorimotor impairments in a standard neurological examination (11 men, 9 women; mean age 36.2 +/- 10.7 years). Thirteen patients had sustained mild, 2 moderate, and 5 severe TBI. Twenty healthy controls were matched for age and gender. INTERVENTION: None. MAIN OUTCOME MEASURES: A dual-plate force platform recorded the amplitude and velocity of the center-of-pressure fluctuations in the anteroposterior (AP) and lateral (LAT) sway directions during quiet standing. Also, the speed and fluency of weight shifting using visual feedback was registered. Both balance tasks were combined with an arithmetic task, whereas quiet standing was also tested with visual deprivation. RESULTS: Compared to controls, TBI patients showed an increase of over 50% in AP and LAT sway, and a weight-shifting speed 20% lower. Dual-task interference was never significant. Visual deprivation was most detrimental for the TBI patients, particularly for LAT sway control. CONCLUSION: A long-term overall reduction in both static and dynamic control of posture can be present after TBI, even in patients without clear neurological deficits. Force-plate recordings can identify such (latent) balance problems. Visual deprivation during quiet standing appears a simple, sensitive test for postural instability related to sensory integration deficits.

Adolescent↗

Work schedule and task factors in upper-extremity fatigue.

We tested the combined effects of work schedule and task factors on upper-extremity fatigue in the laboratory during 8-h and 12-h shift schedules. Participants performed a simulated manual assembly task at three repetition rates and three torque loads and self-adjusted their work cycle duration to maintain fatigue at moderate levels. Work cycle durations decreased with increases in both load level and repetition rate. Fatigue was observed more quickly with increasing time on shifts and during night shifts compared with day shifts. Work schedule effects were most apparent at lighter workloads, with minimal differences at higher workloads. The highest fatigue levels were observed during 12-h night shifts, with similar levels reached by the end of both the week of 8-h night shifts and the week of 12-h day shifts. Overall durations were 20%-30% shorter than in previous short-term studies, which was likely a result of the more realistic work schedules used in this study. Results from this study could be applied to the design of work-rest schedules for manual tasks involving the upper extremities.

Adult↗