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PubMed2000

Fitness for work: the need for conducting a job analysis.

Ensuring that employees are both physically fit for work by matching their capabilities with the physical requirements of their job, and physically fit for life by promoting health-related physical activities, are important and under-utilized tools in a company's arsenal for reducing absence and ill-health retirement (IHR). Both the Health and Safety at Work Act (1974) and the Disability Discrimination Act (1995) require evidence-based approaches to setting physical and medical employment standards. Proven fitness-related strategies include redesigning the most demanding tasks, selecting and training personnel who possess the necessary physical attributes, and assessing and redeploying personnel to jobs within their capability. An essential precursor to pursuing these strategies is to conduct a job analysis to quantify the physical demands of the job.

Absenteeism↗

PubMedDate not supplied

Cardiovascular reactivity to psychological challenge: conceptual and measurement considerations.

OBJECTIVE AND METHODS: This article is a selective review of recent findings bearing on the conceptualization and measurement of cardiovascular reactivity to psychological challenge, with a focus on several issues relevant to the reliability, content validity, construct validity, and criterion validity of these measures. RESULTS AND CONCLUSIONS: With respect to reliability, use of standardized task demands and aggregated scores are associated with enhanced short-term reliability, but the long-term reliability of cardiovascular reactivity has not been sufficiently documented. With respect to content validity, existing evidence suggests that "vascular" or "cardiac" tasks may evoke responses that reflect similar distributions of individual difference, whereas associations between responses to "physical" and "psychological" tasks are modest. The evidence is not clear at present with respect to the importance of including affective or interpersonal stimuli as part of trait reactivity assessments. With respect to construct validity, existing data show that cardiovascular reactivity to psychological challenge is largely independent of standard measures of autonomic function. With respect to criterion validity, recent studies point to a number of methodological limitations that may have restricted our ability to detect lab-to-life generalizability of reactivity measures in the past. Continued progress in understanding and measuring reactivity as an individual difference dimension is essential in helping us to evaluate emerging evidence examining the relationship between reactivity and disease risk.

Cardiovascular Diseases↗

PubMed1990

The effects of spot treatments on performance in a driving simulator under sober and alcohol-dosed conditions.

Accident studies have identified nighttime conditions on rural roads as particular problems for alcohol-impaired drivers. Uneventful driving is hypothesized to result in progressive degradation of tracking performance and a reduced ability to handle the demands of hazardous locations, such as curves. To address these problems, four spot treatments (i.e. herringbone road marking, flashing beacon, chevron, and post delineator) were evaluated in a driving simulator. Twelve subjects drove a simulator under two conditions of task demand (with and without obstacles) and three levels of blood alcohol concentration (BAC): .00%, .07%, and .12%. The purpose of the study was to determine whether providing enhanced visual information about hazardous areas would improve the performance of subjects when sober or alcohol-dosed. Driver performance measures included speed, lateral position, and lateral acceleration on the approach and negotiation of horizontal curves of varying length and curvature. The results indicate that spot treatment effects were primarily curve-specific rather than uniform across curves. The effectiveness of spot treatments as alcohol countermeasures is discussed.

Accident Prevention↗

PubMed2006

Genetic and environmental contribution to postural balance of older women in single and dual task situations.

The purpose of the present study was to examine the effect of a second task on postural balance and to determine the role of genetic influences on postural balance when dual tasking among 206 monozygotic and 227 dizygotic female twins, aged 63-76 years. Balance was measured as medio-lateral and antero-posterior velocity of the centre of pressure (COP) (mm/s) and velocity moment (mm(2)/s) while standing on a force platform. Doing an arithmetic task increased movement of the COP while the hand motor task had no effect on movement of the COP. The genetic contribution to balance in the single task situation was minor (14%, 95% confidence interval, CI: 11-35%) whereas in the dual task situation it was moderate (28%, 95% CI: 0.02-42%). The finding can be explained in the light of the underlying phenotypes of dual tasking, such as cognitive processing that is found to be under considerable genetically controlled even in old age. Moreover, the present study supports previous studies suggesting that, especially among older people, when simultaneously maintaining balance and performing another cognitively demanding task, additional central processing is recruited.

Aged↗

PubMed2001

Brain regions involved in prospective memory as determined by positron emission tomography.

Prospective memory (PM) refers to the functions that enables a person to carry out an intended act after a delay. Despite the ubiquity of this behaviour, little is known about the supporting brain structures and the roles that they play. In this study, eight healthy participants performed four different PM tasks, each under three conditions: a baseline, and two conditions involving an intention. In the first of the intention conditions, subjects were asked to make a novel response to a certain class of stimuli whilst performing an attention-demanding task. However, the expected stimuli never actually occurred. In the second intention condition subjects were expecting to see these stimuli as before, and they did occur on approximately 20% of trials. Relative to the baseline condition, increases in regional cerebral blood flow (rCBF) as estimated by oxygen-15 positron emission tomography technique across all four tasks were seen in the frontal pole (Brodmann's area 10) bilaterally, right lateral prefrontal and inferior parietal regions plus the precuneus when subjects were expecting a PM stimulus regardless of whether it actually occurred. Further activation was seen in the thalamus when the PM stimuli occurred and was acted upon, with a corresponding rCBF decrease in right lateral prefrontal cortex. It is argued that the first set of region play a role in the maintenance of an intention, with the second set involved additionally in its realisation.

Adult↗

PubMed2003

Spectral dynamics of electroencephalographic activity during auditory information processing.

Dynamics of electroencephalographic (EEG) activity during auditory information processing were evaluated in response to changes in stimulus complexity, stimulus discriminability and attention using the oddball paradigm. In comparison to pre-stimulus baseline conditions, auditory stimulation synchronized EEG activity in delta, theta and alpha frequency bands. Event-related synchronization (ERS) effects were greatest at approximately 3 Hz (theta frequency band), and their magnitude depended on stimulus and task demands. Event-related desynchronization (ERD) of EEG activity was observed in the beta frequency band. This effect was greatest at approximately 21 Hz but occurred only for easily discriminable stimuli in attention-related target conditions. Because active discrimination tasks also required a button-press response with the right hand, ERDs involved more complex responses that may be related to a combination of perceptual, motor and cognitive processes. These results demonstrate that oddball and attention-related EEG responses to auditory stimulation could be characterized in the frequency domain. The specific design and analysis features described herein may prove useful since they provide a simple index of the brain's response to stimulation while at the same time provide powerful information not contained in typical time domain analysis.

Adult↗

PubMed1997

Frequent short rest breaks from computer work: effects on productivity and well-being at two field sites.

Computer operators at two work sites (n = 73, n = 19) were prompted to take three 30-s and one 3-min break from computer work each hour in addition to conventional rest breaks. Some operators were asked to perform stretching exercises during the short breaks. Mood state and musculoskeletal discomfort were assessed at each work site over a 2- or 3-week baseline period and a 4- or 6-week treatment period, respectively. Operator productivity measures were obtained from company records. Operators complied with about half of the added breaks but favoured 3-min breaks over 30-s breaks. No improvement in productivity or well-being was found at the larger work site. At the smaller work site, productivity, eye, leg and foot comfort all improved when the short breaks included stretching exercises. These results provide evidence that frequent short breaks from continuous computer-mediated work can benefit worker productivity and well-being when the breaks integrate with task demands.

Adult↗

PubMedDate not supplied

Cognitive impairments in depression.

Depressed patients perform poorly on memory tests. This may reflect a failure to employ encoding strategies that facilitate recall or a generalized inability to allocate cognitive effort to more difficult tasks. Inpatients with major depression or personality disorders and age- and IQ-matched normal controls were administered an automatic frequency of occurrence test and verbal paired associated recall and recognition memory tests. There was no difference in frequency judgments among the subject groups. Both depressed and personality disordered groups recalled and recognized fewer words than normal subjects, with the depressed subjects tending to recall and recognize the fewest words. There was a strong effect of task difficulty on memory performance but this effect was consistent across subject groups. These findings suggest that the poorer performance of depressed patients on memory tests reflect basic memory impairments rather than a general inability to allocate cognitive effort to more demanding tasks. However, these impairments may not be specific to depression but may reflect general effects of psychopathology on memory.

Adult↗

PubMed2006

A common prefrontal-parietal network for mnemonic and mathematical recoding strategies within working memory.

Previous studies have indicated that the lateral prefrontal cortex (LPFC) is closely involved in strategic recoding, even when such processes lessen task demands. For example, 2 studies presented, in the spatial and verbal domains, sequences of stimuli for participants to retain during a short interval and then retrieve. Stimuli were either randomly arranged or structured (forming symmetries and regular shapes for the spatial task and mathematical patterns for the verbal task). Although participants performed the structured tasks better by reorganizing or "chunking" them into more efficient forms, LPFC activity was greater for the structured compared with the random sequences. However, although these results demonstrate that LPFC is involved in strategic recoding, regardless of the type of modality, it remains to be seen whether such a result generalizes to different types of strategic recoding processes. To test this, we presented digit sequence trials that separately emphasized mnemonic or mathematical recoding strategies. While participants were able to gain a performance benefit from either type of recoding strategy, increased LPFC activity was observed for both mathematical and mnemonic recoding trials, compared with either unstructured sequences or control conditions matched for mathematical or mnemonic processes. However, mathematically structured trials activated the LPFC significantly more than mnemonic recoding trials. In addition, lateral posterior parietal cortex was consistently coactivated with LPFC for strategic recoding trials, both in the current experiments and in previous related studies. We conclude that a prefrontal-parietal network is involved in strategic recoding in working memory, regardless of the type of recoding process.

Adult↗

PubMed1998

Deprivation state but not nicotine content of the cigarette affects responding by smokers on a progressive ratio task.

In two experiments, we used a progressive ratio schedule to explore factors associated with smoking motivation. In study 1, smokers who had abstained for more than 8 h bar-pressed for longer to obtain puffs on a cigarette than did non-deprived smokers. Neither group, however, showed nicotine-induced improvements in performance on an attention-demanding task. In the second study, two groups of minimally deprived smokers worked on the progressive ratio task for puffs of either a standard or an ultralow nicotine cigarette. The amount of work expended for puffs was the same for both cigarettes. The groups were also indistinguishable in terms of their subjective experience of the impact of smoking. These results suggest that the addition of nicotine to the cigarette may not have an immediate impact on the effort expended for a puff on that cigarette, and that short term changes in craving may be observed independent of satiety effects associated with nicotine ingestion. We conclude that the progressive ratio task is a useful and sensitive measure of desire to smoke, although the two experiments highlight the complexity of the relationship between subjective, objective and behavioural measures of smoking and nicotine ingestion in humans.

Adolescent↗

PubMed2004

Ketamine disrupts frontal and hippocampal contribution to encoding and retrieval of episodic memory: an fMRI study.

The N-methyl-D-aspartate (NMDA) receptor antagonist ketamine produces episodic memory deficits. We used functional magnetic resonance imaging to characterize the effects of ketamine on frontal and hippocampal responses to memory encoding and retrieval in healthy volunteers using a double-blind, placebo-controlled, randomized, within-subjects comparison of two doses of intravenous ketamine. Dissociation of the effects of ketamine on encoding and retrieval processes was achieved using two study-test cycles: in the first, items were encoded prior to drug infusion and retrieval tested, during scanning, on drug; in the second, encoding was scanned on drug, and retrieval tested once ketamine plasma levels had declined. We additionally determined the interaction of ketamine with the depth of processing that occurred at encoding. A number of effects upon task-dependent activations were seen. Overall, our results suggest that left frontal activation is augmented by ketamine when elaborative semantic processing is required at encoding. In addition, successful encoding on ketamine is supplemented by additional non-verbal processing that is incidental to task demands. The effects of ketamine at retrieval are consistent with impaired access to accompanying contextual features of studied items. Our findings show that, even when overt behaviour is unimpaired, ketamine has an impact upon the recruitment of key regions in episodic memory task performance.

Adolescent↗

PubMed2003

Why do older adults decide they are having difficulty with a task?

OBJECTIVE: Previous studies have identified risk factors for decline in physical function, but they have not examined specific reasons older adults report difficulty with mobility tasks. DESIGN: Community-dwelling people ( n = 160) aged 59 yr and older in an observational cohort study were questioned to determine the most common cited reasons for self-reported difficulty in task performance. RESULTS: Mobility tasks were most often reported to be difficult (66%). The reasons cited for difficulty in low exercise tolerance tasks were task modification by method (33%) and rate (33%). For high exercise tolerance tasks, reasons cited included having to modify the rate of performing the task (20%) or the method (13%). Among those who reported difficulty with low exercise tolerance mobility tasks, >80% reported modification (odds ratio, 46.4 [95% confidence limits: 9.75, 220.51]) and 32% also report frequency change (odds ratio, 5.9 [95% confidence limits: 2.72, 12.85]) as the reason for perceiving difficulty. For those who reported difficulty performing high exercise tolerance-demanding tasks, >90% reported modification (odds ratio, 5.5 [95% confidence limits: 2.05, 14.88]) and 61% also report frequency changes (odds ratio, 3.9 [95% confidence limits: 1.93, 8.04]). CONCLUSION: The findings suggest that people are able to cite specific reasons for difficulty with mobility task performance, most commonly related to task modification.

Activities of Daily Living↗

PubMed2002

Malleable attentional resources theory: a new explanation for the effects of mental underload on performance.

This paper proposes a new theory to account for the effects of underload on performance. Malleable attentional resources theory posits that attentional capacity can change size in response to changes in task demands. As such, the performance decrements associated with mental underload can be explained by a lack of appropriate attentional resources. These proposals were explored in a driving simulator experiment. Vehicle automation was manipulated at 4 levels, and mental workload was assessed with a secondary task. Eye movements were also recorded to determine whether attentional capacity varied with mental workload. The results showed a clear decrease in mental workload associated with some levels of automation. Most striking, though, were the results derived from the eye movement recordings, which demonstrated that attentional capacity varies directly with level of mental workload. These data fully supported the predictions of the new theory. Malleable attentional resources theory suggests that future vehicle designers should employ their technology in driver support systems rather than in automation to replace the driver. The implications of this theory are discussed with regard to capacity models of attention as well as to the design of future vehicle systems.

Adult↗

PubMed2003

Probed recall for serial order deficits in short-term memory in schizophrenic patients.

BACKGROUND: Patients with schizophrenia frequently display problems in tasks demanding working memory. In a previous study, we examined short-term memory (STM) for serial order by having participants recall lists of letters from the first item to the last item in the order in which they were presented, and we examined the types of errors made (e.g., omissions, intrusions and movements; [Neuropsychology 15 (2001) 128]). We found that the disproportionate errors schizophrenic patients made were omissions at the end of six-item lists, a finding we suggested might reflect patients' longer output times, which adds to information maintenance demands. If this is the case, we predicted that the group difference in the terminal positions could be eliminated through the use of a probed recall paradigm. METHOD: In the current study, 26 schizophrenic patients and 33 control participants were tested on a probed recall task that was similar to our previous serial recall task except that instead of recalling the whole sequence of letters, participants were probed as to which letter appeared in a specific position in the sequence. RESULTS: We found that when participants were probed for later positions, recall was equivalent in the groups (i.e., recency), but disproportionately worse in patients for earlier positions. CONCLUSIONS: We suggest that schizophrenic patients' limited STM span for serial order is not attributable to a selective deficit in memory for serial order. Rather, we propose that it may be explicable in terms of impaired information maintenance and thus this becomes evident in conditions involving longer sequences of stimuli.

Adult↗

PubMed2001

Task-specific resistance training to improve the ability of activities of daily living-impaired older adults to rise from a bed and from a chair.

OBJECTIVES: To determine the effect of a 12-week intervention to improve the ability of disabled older adults to rise from a bed and from a chair. DESIGN: Subjects were randomly allocated to either a 12-week task-specific resistance-training intervention (training in bed- and chair-rise subtasks, such as sliding forward to the edge of a chair with the addition of weights) or a control flexibility intervention. SETTING: Seven congregate housing facilities. PARTICIPANTS: Congregate housing residents age 65 and older (n = 161, mean age 82) who reported requiring assistance (such as from a person, equipment, or device) in performing at least one of the following mobility-related activities of daily living: transferring, walking, bathing, and toileting. MEASUREMENTS: At baseline, 6 weeks, and 12 weeks, subjects performed a series of bed- and chair-rise tasks where the rise task demand varied according to height of the head of the bed, chair seat height, and use of hands. Outcomes were able or unable to rise and, if able, the time taken to rise. Logistic regression for repeated measures was used to test for differences between tasks in the ability to rise. Following log transformation of rise time, a linear effects model was used to compare rise time between tasks. RESULTS: Regarding the maximum total number of bed- and chair-rise tasks that could be successfully completed, a significant training effect was seen at 12 weeks (P = .03); the training effect decreased as the total number of tasks increased. No statistically significant training effects were noted for rise ability according to individual tasks. Bed- and chair-rise time showed a significant training effect for each rise task, with analytic models suggesting a range of approximately 11% to 20% rise-time (up to 1.5 seconds) improvement in the training group over controls. Training effects were also noted in musculoskeletal capacities, particularly in trunk range of motion, strength, and balance. CONCLUSIONS: Task-specific resistance training increased the overall ability and decreased the rise time required to perform a series of bed- and chair-rise tasks. The actual rise-time improvement was clinically small but may be useful over the long term. Future studies might consider adapting this exercise program and the focus on trunk function to a frailer cohort, such as in rehabilitation settings. In these settings, the less challenging rise tasks (such as rising from an elevated chair) and the ability to perform intermediate tasks (such as hip bridging) may become important intermediate rehabilitation goals.

Activities of Daily Living↗

PubMed2002

Rapid natural scene categorization in the near absence of attention.

What can we see when we do not pay attention? It is well known that we can be "blind" even to major aspects of natural scenes when we attend elsewhere. The only tasks that do not need attention appear to be carried out in the early stages of the visual system. Contrary to this common belief, we report that subjects can rapidly detect animals or vehicles in briefly presented novel natural scenes while simultaneously performing another attentionally demanding task. By comparison, they are unable to discriminate large T's from L's, or bisected two-color disks from their mirror images under the same conditions. We conclude that some visual tasks associated with "high-level" cortical areas may proceed in the near absence of attention.

Adult↗

PubMed2003

Haptically creating affordances: the user-tool interface.

Successful use of a hand-held tool requires overcoming the rotational inertia of the hand-plus-tool system. Where an object is grasped affects this rotational inertia. Appropriate choice of grip position may be crucial in the safe, effective, and efficient control of a hand-held tool. In 3 experiments, the authors investigated how choice of grip position on a tool was constrained by task demands. The results suggest that choice of grasp position serves to establish relationships among 3 variables derived from the inertial ellipsoid of the hand-object system (volume, symmetry, and eigenvector angle) in a way that specifically reflected the power or precision constraints of the given task. These variables have previously been shown to play a role in haptic perception of tool function. Changing grasp position on a tool is a way to exert control over the nuances of the user-tool interface.

Choice Behavior↗

PubMed2006

Combined cerebral blood flow effects of a cholinergic agonist (milameline) and a verbal recognition task in early Alzheimer's disease.

RU 35926/CI-979 (milameline) is a partial muscarinic agonist with promnestic effects in animal models. Preliminary animal studies suggest that this agent has the capacity to reverse cholinergic dysfunction and that it may impact on regional cerebral blood flow (rCBF). A total of 10 subjects with Alzheimer's disease (AD) of mild severity underwent high resolution split-dose single photon emission computed tomography (SPECT) during performance of a verbal recognition and control task, both before and after 18 weeks treatment with melameline or placebo. SPECT images were coregistered with individual's magnetic resonance imaging scans allowing extraction of rCBF values from multiple anatomical regions of interest (ROI). The effect of milameline was examined in eight individuals who were found after unblinding to be taking active drug. Effects of milameline were most apparent in the frontal regions, basal ganglia and thalamus. In the group as a whole, the greatest increase in rCBF due to milameline treatment was observed in the left globus pallidus. Response to milameline treatment was associated with increases in rCBF in the cingulate gyrus bilaterally, and less so for the left thalamus. Milameline-related increases in rCBF values were exaggerated by the verbal recognition task. Milameline has a demonstrable effect on cerebral blood flow in mild AD. Consistent with emerging animal data, the effects on rCBF appear most prominent in frontal and subcortical regions in AD subjects. The effects on rCBF appear to be augmented by the performance of a cognitively demanding task, raising the possibility that such tasks could assist in building an awareness of the functional neuropsychopharmacology of drugs designed for cognitive enhancement.

Alzheimer Disease↗