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Results for “Task Shifting”

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PubMed2006

On the role of causal intervention in multiple-cue judgment: positive and negative effects on learning.

Previous studies have suggested better learning when people actively intervene rather than when they passively observe the stimuli in a judgment task. In 4 experiments, the authors investigated the hypothesis that this improvement is associated with a shift from exemplar memory to cue abstraction. In a multiple-cue judgment task with continuous cues, the data replicated the improvement with intervention and participants who experimented more actively produced more accurate judgments. In a multiple-cue judgment task with binary cues, intervention produced poorer accuracy and participants who experimented more actively produced poorer judgments. These results provide no support for a representational shift but suggest that the improvement with active intervention may be limited to certain tasks and environments.

Adult↗

PubMed1985

Fast noninertial shifts of attention.

It was suggested that some discrimination tasks (e.g. discrimination between the letters T and L) require serial search by scrutinizing each letter (target) with a small aperture of focal attention. Here we examine the effect of intertarget distance on discrimination performance, using two targets. We find reduction in performance at short distances, in agreement with masking studies, but constant performance independent of distance outside this masking region. This constant performance is still lower than expected from masking effects and might reflect attentive process. Sequential presentation of the targets with delays up to 30-40 ms, while reducing available processing time, does not cause reduction in performance, thus supporting the suggestion that discrimination of the two targets is a serial process. The independence of performance on distance suggests fast noninertial shifts of attention.

Attention↗

PubMed1983

Contributions to behavioral treatment from studies on programmed access to alcohol.

Major developments in research involving the alcohol-alcoholic interaction are presented against a backdrop of the traditional perspective of alcoholism. Studies explaining the effects of alcohol, factors influencing drinking patterns, the significance of alcohol for the alcoholic, expectations regarding alcohol use and its affective and social consequences, the parameters of alcohol use, the question of control of alcoholism, and a number of treatment related issues are reviewed. It is concluded that much of this research is provocative and may recommend a reassessment of current thinking about the nature of alcohol abuse and dependence. Such a reassessment, however, is seen to be difficult to make, for the task likely will require a paradigmatic shift.

Affect↗

PubMed1989

Effect of d-amphetamine, secobarbital, and marijuana on choice behavior: social versus nonsocial options.

The effects of oral d-amphetamine and secobarbital and smoked marijuana on human social conversation and preference for socializing were studied in three separate experiments. During experimental sessions, active drug or placebo was administered using an acute or divided dosing procedure. Subjects who received drug then engaged in a discrete-trial choice procedure in which they made a series of mutually exclusive choices between a social (talking with their nondrugged partner) and nonsocial (sitting quietly alone) option. Lapel microphones and voice operated relays measured seconds of speech. Subjects engaged in greater amounts of conversation and chose the social option more frequently following acute dosing of d-amphetamine and secobarbital compared with placebo. Acute administration of marijuana did not significantly affect social speech or choice behavior, producing slight decreases in both measures. Acute dosing of all drugs significantly increased subjective drug effect or drug high; however, only secobarbital affected the circular lights task, producing significant performance decrements. The shifts in preference toward the social option observed with d-amphetamine and secobarbital suggest that these drugs increased the reinforcing effects of socializing relative to sitting alone. This may be one mechanism by which psychoactive drugs facilitate social conversation.

Adult↗

PubMed1979

Cerebral potentials during smooth goal-directed hand movements in right-handed and left-handed subjects.

During smooth goal-directed hand movements a negative potential shift can be recorded from the human scalp. This goal-directed movement potential (GDMP) is preponderant over central areas with a maximum at the vertex and, over the motor cortex, contralaterally larger than ipsilaterally to the moving hand. In 11 right-handed and 6 left-handed subjects, the morphology and distribution of these potential shifts were studied in relation to task differences, moving hand and handedness. The results show a functional differentiation of two components of the GDMP: (1), a lateralized, slow negative wave, restricted to the precentral area and selectively varying with the hand used, and (2), a widespread, bilateral symmetrical component, selectively influenced by task-specific and individual factors. Two effects reflect an influence of the subject's handedness on the GDMP: (A) averaged for both hand conditions, there are larger amplitudes over the hemisphere contralateral to the dominant hand, and (b), averaged for both hemispheres, larger amplitudes result from using the non-dominant hand.

Adolescent↗

PubMed1992

Late cognitive event-related potentials in adult Down's syndrome.

Event-related electroencephalogram (EEG) potentials (ERPs) using two different tasks were measured in 14 adults with Down's syndrome (DS; mean age 32 years) without clinically detectable cognitive decline. Two groups, young healthy (YH) and old healthy (OH) adults, served as controls. In the oddball task, DS had prolonged N1 and earlier P2 latencies than the control groups. P3 latency was delayed in comparison to YH. In the PushWait task, P3 latency was later in DS than in YH and OH. In both tasks, DS showed a marked amplitude shift towards positivity overlapping the N1-P2 complex and seemingly also P3: The P3 amplitude evoked by target tones and by "Push" was shifted towards anterior sites resulting in a Cz maximum. Changes of the N1 latency and amplitude in DS may be related to enhanced arousal during stimulus processing, indicating a possible defect of central inhibitory mechanisms. The study suggests that differentiated ERP procedures provide information on adult DS cognition exceeding those given by mere P3 latency measurements. Such procedures may be useful in the evaluation of the cognitive decline due to precocious aging or Alzheimer-type dementia in DS.

Adult↗

PubMed1980

Some baseline effects on the CNV.

A method is described to investigate how the contingent negative variation (CNV), developing in the S1-S2 interval of a reaction task, is influenced by slow potential shifts (SPSs) occurring before S1. Enhanced CNV amplitudes were found when the SPSs before S1 were positive, whereas with negative SPSs attenuated amplitudes were obtained.

Cerebral Cortex↗

PubMed2005

Train drivers' sleep and alertness during short relay operations.

Within Australia, there has been a recent expansion of relay working operations. To address concerns about the amount of sleep obtained by drivers in relay vans, and potential deficits in alertness associated with relay work, the current study assessed the sleep behaviour and alertness of 15 train drivers working short (<48 h) relay operations. In total, drivers obtained 8-12h of sleep during the relay trip (which took approx 40 h). Overall, they reported that they felt more alert following each sleep period. Drivers were able to sustain attention during the 10-min vigilance tasks administered before and after each shift. These findings suggest that the amount of sleep obtained in crew vans during short relay operations is sufficient to maintain alertness during the trip. They also emphasise the importance of scheduling shifts to maximise the number of sleep opportunities that occur between 2200 and 0700 h.

Adult↗

PubMed2005

Attentional load of the primary task influences the frontal but not the temporal generators of mismatch negativity.

According to the model hypothesized by Näätänen and Michie, the generation of the mismatch negativity (MMN) requires a mismatch detection, taking place in temporal areas, followed by the activation of frontal generators, underlying attention switching toward the deviant stimulus. We aimed at verifying whether the activation of temporal and frontal regions is dependent on the amount of attentional resources allocable toward the deviant stimulus. We recorded event-related potentials (ERPs) in nine healthy subjects while reading and during a demanding visual task (Multiple Features Target Cancellation, MFTC). Raw data were further evaluated by Brain Electrical Source Analysis (BESA). During the Reading condition, distraction toward the unattended auditory stimuli was reflected by the enhancement of the N1 response to frequent stimuli and by the elicitation of a P3a response to deviant ones. The MMN distribution was explained by bilateral temporal dipoles. During the MFTC condition, no P3a was detected, while source analysis showed the activation of a right frontal generator. Temporal dipoles showed no change between the two conditions: we thus conclude that the earlier mismatch detection is independent on the attentional load. By contrast, the activation of a right frontal subcomponent occurred only during the high-load task, independently on any actual attention shift reflected by the P3a component. We thus discuss the hypothesis whether the right frontal MMN generator, rather than subserving a simple attention switching toward the deviant stimulus, plays a role in modulating the auditory change detection system ("contrast enhancement" model).

Acoustic Stimulation↗

PubMed2004

Baclofen interactions with nicotine in rats: effects on memory.

Nicotine has been shown in numerous previous studies to significantly improve memory on the radial-arm maze, yet the critical mechanisms underlying this effect are not fully characterized. Nicotine stimulates the release of a number of neurotransmitters important for memory function including (gamma-aminobutyric acid) GABA. The importance of nicotinic-GABA interactions regarding memory is currently unknown. The purpose of the current study was to determine the interactive effects of nicotine and the GABA agonist baclofen on working memory function as measured by choice accuracy in the radial-arm maze. Female Sprague-Dawley rats trained to asymptotic performance levels on a win-shift eight-arm radial maze task were used for assessment of nicotine-baclofen interactions. Low doses of baclofen improved memory performance while higher doses impaired it. Nicotine, as seen before, improved memory performance. Nicotine also significantly reversed the higher dose baclofen-induced deficit. These data show the importance of both nicotinic and GABA systems in working memory function and the interactions between these two transmitter receptor systems. This not only provides information concerning the neural bases of cognitive performance, it also lends insight into new combination treatments for memory impairment.

Animals↗

PubMed1997

Reinforcer revaluation and conditioned place preference.

Conditioned place preference (CPP) tests provide a novel way of testing an animal's ability to respond to direct manipulation of its motivational state. In the first of two studies, rats exhibited an appropriate preference for a place previously paired with either food or fluid, depending on their current motivational state (hungry or thirsty). Preference was independent of the animal's prior exposure to the relevant reinforcer in that motivational state. In the second experiment, a sucrose solution was used to generate a place preference and was subsequently devalued using a LiCl taste aversion procedure. One group (B) received two CTA sessions and two further groups received a single CTA session either with (R), or without (N), a further nonreinforced opportunity to drink sucrose. Group B exhibited a substantial place aversion and a considerable reduction in sucrose consumption in a test following assessment of place preference. A weak place aversion was found in group N and a weak place preference was shown by group R; sucrose consumption in a test following measurement of place preference followed a similar pattern. These two studies indicate that performance on a place preference task is directly sensitive to both shifts in motivational state and reduction in reinforcer value.

Animals↗

PubMedDate not supplied

Chromatic and contrast selectivity in color contrast adaptation.

We used color contrast adaptation to examine the chromatic and contrast selectivity of central color mechanisms. Adaptation to a field whose color varies along a single axis of color space induces a selective loss in sensitivity to the adapting axis. The resulting changes in color appearance are consistent with mechanisms formed by different linear combinations of the cone signals. We asked whether the visual system could also adjust to higher-order variations in the adapting stimulus, by adapting observers to interleaved variations along both the L versus M and the S versus LM cardinal axes. The perceived hue of test stimuli was then measured with an asymmetric matching task. Frequency analysis of the hue shifts revealed weak but systematic hue rotations away from each cardinal axis and toward the diagonal intermediate axes. Such shifts could arise if the adapted channels include mechanisms with narrow chromatic selectivity, as some physiological recordings suggest, but could also reflect how adaptation alters the contrast response function. In either case they imply the presence of more than two mechanisms within the chromatic plane. In a second set of measurements, we adapted to either the L versus M or the S versus LM axis alone and tested whether the changes in hue could be accounted for by changes in relative contrast along the two axes. For high contrasts the hue biases are larger than the contrast changes predict. This dissociation implies that the contrast and hue changes are not carried by a common underlying signal, and could arise if the contrast along a single color direction is encoded by more than one mechanism with different contrast sensitivities or if different subsets of channels encode contrast and hue. Such variations in contrast sensitivity are also consistent with physiological recordings of cortical neurons.

Adaptation, Ocular↗

PubMed1980

Mental-task instructions and optokinetic nystagmus to the left and right.

The frequency of elicited optokinetic nystagmus (OKN) in both directions was studied in subjects instructed to perform mental tasks thought to be asociated primarily with either the right or left hemisphere or a combination of both. A negative relationship between OKN frequency and right-hemisphere activity was more strongly confirmed than the alternative hypotheses that OKN frequency would be negatively related to the total amount of inner processing or to the amount of visualization required by a task. A significantly higher frequency of OKN was elicited (in nonmyopic subjects) when the stripes were moving in the direction contralateral to the hemisphere presumably involved in the instructed mental task. Subjects showing higher rates of right lateral eye shift (in an interview situation) made greater adjustments in OKN frequency according to the nature of the mental task.

Dominance, Cerebral↗

PubMed1985

An examination of the relationship of reimbursement and organizational structure to the use of hospice volunteers.

This article examines the use of volunteers in hospice based on a national study of hospice programs. The data collected as part of the study make it possible to address several questions related to the prevalence and role of volunteers. Does the prevalence of volunteers decrease with the availability of reimbursement for hospice services? Is reimbursement related to a shift in the types of activities performed by volunteers? Is the level of volunteer involvement and the mix of volunteer activities related to type of hospice organization? Although it was hypothesized that volunteer activities would shift to non-patient-related tasks with the availability of reimbursement, this was not found to be the case. The availability of Medicare reimbursement for hospice services was not related to a decrease in the ratio of volunteers to paid staff. Freestanding hospices utilized volunteers to a greater degree than institution-affiliated hospices.

Data Collection↗

PubMed2005

Clustering and switching on verbal and figural fluency functions in adults with attention deficit hyperactivity disorder.

INTRODUCTION: Neuropsychological studies of adult patients with ADHD have revealed marked disturbances of executive functions including impairments of attention, working memory, impulsivity, shifting, and divergent thinking. Phonemic fluency tasks, in particular, have been shown to be sensitive measures for the assessment of executive functions of adults with ADHD. METHODS: The present study has examined figural fluency and both phonemic and semantic verbal fluency in 34 adult patients with ADHD and 34 healthy participants. For evaluation of fluency performance the number of words or designs, the number of repetitions and the number of deviations from test rules were calculated. Furthermore, clustering strategies and switching responses were analysed. In comparison with healthy participants, patients with ADHD produced significantly fewer words or designs, but they did not differ from healthy participants in the number of repetitions or rule violations. RESULTS: Analysis of switching and clustering showed that patients produced significantly fewer switching responses on both verbal fluency tasks, although patients tended to generate smaller clusters. Switching on the figural fluency task was unimpaired. CONCLUSIONS: The results of the present study suggest that adult patients with ADHD may suffer from a dysfunction that may affect retrieval processes and the categorisation of knowledge.

Journal Article↗

PubMed1998

The role of implicit memory in controlling a dynamic system.

The relationship between implicit memory and implicit learning is explored. Dienes and Fahey (1995) showed that learning to control a dynamic system was mediated by a look-up table consisting of previously successful responses to specific situations. The experiment reported in this paper showed that facilitated performance on old situations was independent of the subjects' ability to recognize those situations as old, suggesting that memory was implicit. Further analyses of the Dienes and Fahey data replicated this independence of control performance on recognition. However, unlike the implicit memory revealed on fragment completion tasks, successful performance on the dynamic control tasks was remarkably resilient to modality shifts. The results are discussed in terms of models of implicit learning and the nature of implicit memory.

Adolescent↗

PubMed2006

PREDITOR: a web server for predicting protein torsion angle restraints.

Every year between 500 and 1000 peptide and protein structures are determined by NMR and deposited into the Protein Data Bank. However, the process of NMR structure determination continues to be a manually intensive and time-consuming task. One of the most tedious and error-prone aspects of this process involves the determination of torsion angle restraints including phi, psi, omega and chi angles. Most methods require many days of additional experiments, painstaking measurements or complex calculations. Here we wish to describe a web server, called PREDITOR, which greatly accelerates and simplifies this task. PREDITOR accepts sequence and/or chemical shift data as input and generates torsion angle predictions (with predicted errors) for phi, psi, omega and chi-1 angles. PREDITOR combines sequence alignment methods with advanced chemical shift analysis techniques to generate its torsion angle predictions. The method is fast (<40 s per protein) and accurate, with 88% of phi/psi predictions being within 30 degrees of the correct values, 84% of chi-1 predictions being correct and 99.97% of omega angles being correct. PREDITOR is 35 times faster and up to 20% more accurate than any existing method. PREDITOR also provides accurate assessments of the torsion angle errors so that the torsion angle constraints can be readily fed into standard structure refinement programs, such as CNS, XPLOR, AMBER and CYANA. Other unique features to PREDITOR include dihedral angle prediction via PDB structure mapping, automated chemical shift re-referencing (to improve accuracy), prediction of proline cis/trans states and a simple user interface. The PREDITOR website is located at: http://wishart.biology.ualberta.ca/preditor.

Internet↗

PubMed2004

Ergonomics in mining.

Like other areas of occupational health and safety (OHS) ergonomics is evolving and becoming more integrated into overall work management systems. As we learn more about the complex interaction between psychosocial and physical factors in the aetiology of work-related illness and injury the more we rely on managers to 'get it right' if we are to prevent these conditions. Risks to health and safety in the mining industry posed by longer shift lengths, higher work loads, less task variation and decision latitude have not really been well researched. Heavy physical workloads and stresses are still areas of concern, but are likely to be intermittent rather than constant. Recent research confirms current thinking rather than shedding new light on the subject. The contribution of slips, trips and falls and increasing age of miners to manual handling injuries is still not clear. In some cases sedentary work and the operation of machinery has completely replaced heavy physical work. The issues of machinery design for operations and maintenance and whole-body vibration exposures when operating machines and vehicles are becoming more critical. The link between prolonged sitting, poor cab design and vibration with back and neck pain is being recognized but has yet to be addressed in any systematic way by the mining industry. On the plus side some mining companies have well-developed participative approaches to problem solving and these need to be extended to areas such as ergonomics.

Age Factors↗