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PubMed1976

Laboratory investigation of "biorhythms".

Three subjects were tested on an information processing task on a daily basis for a period of 70 d. Performance measurement included reaction time, movement time, and information processing rate. The data set obtained was subjected to Fast Fourier Transforms (FFT) in an attempt to identify periodicities in performance. Twelve significant harmonics were identified and nine were found to be within 1 d of at least one of the cycles hypothesized by the theory of "biorhythms." The probability of this occurring by chance is remote (p less than 0.05), assuming a uniform distribution of significant amplitude. The results were interpreted as suggesting the possibility of a biorhythmic influence in the performance of the task.

Adult↗
PubMed1991

Mental planning and anticipatory processes with acute and chronic frontal lobe lesions: a comparison of maze performance in routine and non-routine situations.

A series of computerized mazes were masked during presentation allowing only partial view of their structure. Patients suffering from acute or chronic unilateral frontal (medial, lateral) or retrorolandic (temporal, parietal) lesions and non-brain-damaged controls were required to pass through the mazes repeatedly, until they solved them without reaching a dead end. Because the mazes could not be viewed in their entirety at any one time, the subjects were forced to mentally generate and apply a plan of the maze. The first ("non-routine" situation), the second and the last ("routine" situation) trials of the mazes were analysed separately. The prefrontal cortex is supposed to subserve important functions in the planning of behaviour in unfamiliar, non-routine situations. Shallice (Phil. Trans. R. Soc. Lond. B298, 199-209, 1982; From Neuropsychology to Mental Structure, Cambridge University Press, Cambridge, 1988) therefore postulated that the behaviour of patients with frontal lobe lesions should not be disturbed in routine situations, but rather these patients should exhibit difficulties in dealing with new and unfamiliar situations. In the present investigation, patients with acute and chronic frontomedial lesions exhibited deficits in generating mental plans. Patients with acute frontomedial lesions made a larger number of errors in their second trials and subsequently required more trials to reach task criterium. Patients with chronic frontomedial lesions showed more frequent rule-breaking behaviour in their second trials. The analysis of maze performance in the first trial and that trial in which task criterion was achieved, showed that frontal lobe patients were impaired in neither routine nor non-routine situations. The observed results suggest a modification concerning Shallice's assumptions. Patients with frontomedial lesions are not generally incapable of dealing with non-routine situations. But they seem to be slower than patients with retrorolandic lesions and controls in profiting from experiences made in an unfamiliar, non-routine situation represented by the first explorations of new maze problems. This deficit can possibly be explained by the observation that anticipatory processes or the formation of expectations about possibly correct decisions in non-routine situations were altered in acute and chronic frontomedial patients. When these patients reached a maze intersection for the first time and therefore had no information about the continuation of the correct path, they showed significantly different intuitive directional decisions when compared to controls.

Adult↗
PubMed1976

The effects of divided attention on information processing in manual tracking.

Six subjects performed a manual tracking task concurrently uith each of two secondary tasks: in input task (auditory signal detection) and an output task (application of a constant force). A feedback-control analysis of tracking performance was utilized to analyze the time-sharing decrements observed in mean squared errer, in terms of components due to processing delay, addition of internal processing noise, and change in response bias (tracking gain). The results indicated that only the parameters measuring noise and gain were sensitive to time-sharing conditions, and these only to concurrent performance of the force application task. It is concluded that limits of attention in dual-task performance are more severe in output than in input stages of processing, but that these limits are not necessarily those of a single-channel bottleneck. Instead, a broader conception of attention is proposed: one that included changes in processing noise and shifts in response bias, as attention-related phenomena.

Attention↗
PubMed1978

Performance and efficiency of intercollegiate cross-country skiers.

Ten male intercollegiate cross-country skiers were studied to identify factors influencing competitive performance and to estimate the efficiency of energy expenditure in skiing. The variables examined were maximum oxygen intake, as determined by both uphill treadmill running and by maximal level skiing, physical characteristics, strength and experience in cross-country skiing and racing. Multiple regression analysis showed that racing experience, cardiorespiratory fitness, and body fat percentage were significant factors in racing success. The net mechanical efficiency at this level of competition was estimated at 21.3%.

Adolescent↗
PubMed1990

Genetic influences on respiratory sinus arrhythmia across different task conditions.

Respiratory sinus arrhythmia (RSA) has been shown to be a sensitive index of vagal cardiac control. We studied the genetic and nongenetic influences on individual differences in RSA in a sample of 160 adolescent twins. RSA was measured during rest and across two different tasks. Results show that heritability is task dependent. The amount of genetic variance is the same, however, during rest and task conditions. Because nonshared environmental variance decreases during tasks, heritability is larger for RSA measured under more stressful conditions than for RSA as measured during rest. Multivariate models assessed the continuity of the genetic and environmental influences and show genetic influences to be the same across different conditions, while environmental influences are different. More specifically, a one-factor model is found for genetic influences and a second-order autoregressive model for the environmental factors.

Adolescent↗
PubMed1990

[Basic research on measurement of mental work load utilizing physiological information].

Various definitions and models have been proposed to evaluate mental work load, for example, task time analysis method and secondary task method based on single channel model. However, an evaluating method utilizing physiological information has been comparatively newly proposed. Therefore, this method has not been adequately examined with respect to its relation to be heretofore proposed methods and to its practical usefulness in evaluating mental work load. In this study comparison was made of various evaluating methods, i.e. task time analysis method, secondary task method, method utilizing physiological information, and subjective score method with emphasis on the method utilizing physiological information when a modeled experiment was conducted. In evaluating the regression by the experimental results, the adopted standard was time shared fraction (TSF), which was computed as the relative required time compared to actual permitted time based on the single channel model. The main results can be summarized as follows: (1) The evaluated TSF value is a useful index if it can be computed, because it reflects the individual ability of each subject, is proportional to the amount of given information, and is most faithful to the definition of single channel model. (2) The TSF value is significantly correlated to the value obtained by existing secondary task method and subjective score method. Thus, this result justifies the above mention. (3) In the adopted physiological indicators of this experiment, SRRP (skin resistance reflex pulse rate) has the strongest correlation to TSF value. Furthermore, this SRRP is relatively not affected by individual difference and is significantly correlated to subjective score and secondary task in the constant condition of atmospheric temperature and subject's arousal level and in the repetitive task.

Adult↗
PubMed1988

Evaluation of five systems to determine technician staffing in a unit dose cart-filling area.

The development and evaluation of predictive systems to determine staffing needs in a centralized unit dose cart-filling area were studied. Data concerning actual cart-filling time and the hospital's daily census, by total beds and by bed type, were collected over 55 days. Four predictive systems were then developed, as follows: simple average, range average, simple regression, and multiple regression. In addition to these mathematical systems, a pharmacist "best-guess" system was devised, whereby the pharmacist directing the cart-filling area estimated the staffing needs on a daily basis during the trial period. The five systems were then used to predict cart-filling time daily over 14 days. During this time, the actual filling time was recorded and compared with the times predicted by the five systems. The differences among the actual or predicted mean cart-filling times for the five systems were not significant. The pharmacist best-guess system was on average the most accurate in detecting different staffing needs; the advantage of this system is that the pharmacist can evaluate differences in work habits among the scheduled technicians, which the mathematical models would be unable to do. The simple average system correlated well with changes in filling time and most precisely predicted variability in census. Although none of the systems was superior in all respects, a combination of the pharmacist best-guess and simple-average systems appeared to be the best method for predicting daily technician staffing needs in the central cart-filling area.

Data Collection↗
PubMed1977

Cost of using permanent vs. disposable ware. Studies in two school systems.

In this study, the cost of using permanent ware and disposable ware in selected schools was compared. Included in the permanent ware study were the costs of: The ware, machine washing of the ware (including labor time and consumption of utilities, detergents, and chemicals), and refuse removal. Data collected in the disposable ware study were: Meal count; number of items of ware used; labor time; and cost of equipment, supplies, and refuse removal. The cost per student was 4 cents for permanent ware and 10 cents for disposable ware. Although the findings in the schools studied point to an economic advantage in using permanent ware, other considerations might prompt a decision in favor of disposable ware.

Cooking and Eating Utensils↗
PubMed1991

A microcomputerized task assessment of cognitive change in normal elderly and young adults.

There is need for efficient, acceptable quantitative measures of cognitive differences with senescence which, in addition, have potential to discriminate mild dementia from the performance of normal elderly. A microcomputerized method designed to assess attentional capacity was administered to two elderly age groups, 68-79 and 80-87 years of age. A comparison group of young adults, 25-35 and 35-45 years of age, was similarly studied. The two tasks in the procedure (the tracking task, consisting of following a randomly moving target on a video screen, and the probe task, consisting of visual monitoring of a randomly elongating dot in the video screen) are performed separately and then simultaneously (dual task). The tracking task discriminated between the younger groups. Both the tracking and the probe task discriminated between the two older age groups. On discriminant analysis, the best variables for distinguishing older age groups were the logarithms of the single task scores. The performance scores of both elderly age groups were lower on the dual tasks compared with single tasks, but with significant performance decreases only in the probe scores. Comparing all four age groups, the older groups performed less well on the tasks and particularly poorly on the dual tasks. There were no significant gender effects. These initial data will be useful in application of the method for purposes of discriminating mild dementia from normal senescence, and possibly the effects of drugs used to enhance cognitive function.

Adult↗
PubMed1981

Influence of combined visual and vestibular cues on human perception and control of horizontal rotation.

Measurements are made of manual control performance in the closed-loop task of nulling perceived self-rotation velocity about an earth-vertical axis. Self-velocity estimation is modeled as a function of the simultaneous presentation of vestibular and peripheral visual field motion cues. Based on measured low-frequency operator behavior in three visual field environments, a parallel channel linear model is proposed which has separate visual and vestibular pathways summing in a complementary manner. A dual-input describing function analysis supports the complementary model; vestibular cues dominate sensation at higher frequencies. The describing function model is extended by the proposal of a non-linear cue conflict model, in which cue weighting depends on the level of agreement between visual and vestibular cues.

Fourier Analysis↗
PubMed1992

Clarification of the dual task dilemma: lateralized effects for perfunctory and purposeful tasks in left- and right-handed males.

The hypothesis that behavioral asymmetries with the dual task paradigm represent manual dominance was investigated with right- and left-handed males performing verbal and spatial tasks ordered by complexity. Lateralization was assessed for nonideational (perfunctory) and ideational (purposeful) components of tasks with multivariate and ANCOVA procedures. The outcomes of prerequisite tests showed the assumptions for conducting ANCOVA procedures were not satisfied with different handedness groups in the same design. However, results of the multivariate analyses suggest lateralized effects are more likely to represent the cognitive task when interference is high and may represent manual dominance when interference is low.

Adult↗
PubMed1980

Processing control and cost in bacteriology.

Controlled processing was applied to lower respiratory, wound, and cervicovaginal exudates, and urine. The extent of processing was determined by assessment of quality in direct smears and/or by limits placed on complete identification and antimicrobial susceptibility testing of isolates in mixed cultures. Some specimens were not cultured; others were cultured, but certain isolates were identified by colonial morphologic features only. The time in minutes for performing 22 processing operations was determined. The average number of operations performed with processing control was established along with the total cost per minute of labor expended. A 19% reduction was observed in the time expended with controlled processing relative to projected time expended without processing controls. Urine specimens yielded the greatest saving. Processing control speeds recollection of poor-quality specimens, provides reporting of results of examination of all Gram-stained direct smears, minimizes reporting of information potentially misleading to physicians, and may reduce other health-care costs through improved patient care.

Bacteria↗
PubMed1978

Teaching janitorial skills to the mentally retarded: acquisition, generalization, and maintenance.

A task analysis of janitorial skills required for cleaning a restroom was performed. Six subtasks with a total of 181 component responses were identified. Subjects were required to progress through a series of four prompt levels ordered generally from more to less direct assistance for 20 of the most difficult component steps. Another series of four prompts, ordered from less to more direct assistance, was used to teach the other 161 responses. Subjects progressed to the next more intense prompt level contingent on a failure to respond appropriately with less assistance. A multiple baseline across subjects as well as the six subtasks was employed to evaluate the efficacy of the procedures. Six moderately retarded adolescents were trained in their public school. The results show rapid response acquisition, skill generalization to a second restroom, and maintenance of the newly learned behavior. The present research provides evidence of a model for analyzing and training vocational skills to the mentally retarded.

Adolescent↗