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Results for “Task Shifting”

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PubMed1992

Speech perception in adult subjects with familial dyslexia.

Speech perception was investigated in a carefully selected group of adult subjects with familial dyslexia. Perception of three synthetic speech continua was studied: /a/-/e/, in which steady-state spectral cues distinguished the vowel stimuli; /ba/-/da/, in which rapidly changing spectral cues were varied; and /sta/-/sa/, in which a temporal cue, silence duration, was systematically varied. These three continua, which differed with respect to the nature of the acoustic cues discriminating between pairs, were used to assess subjects' abilities to use steady state, dynamic, and temporal cues. Dyslexic and normal readers participated in one identification and two discrimination tasks for each continuum. Results suggest that dyslexic readers required greater silence duration than normal readers to shift their perception from /sa/ to /sta/. In addition, although the dyslexic subjects were able to label and discriminate the synthetic speech continua, they did not necessarily use the acoustic cues in the same manner as normal readers, and their overall performance was generally less accurate.

Dyslexia↗

PubMed2002

Assessing visual performance with progressive addition lenses.

PURPOSE: As a result of lens design limitations, progressive addition lenses (PAL's) present a limited field of view for tasks at intermediate distances, such as with computers. To assess whether this limitation results in diminished visual performance, PAL's were compared with single-vision lenses in four different types of reading tasks in a computer workplace environment. METHODS: Adult subjects performed four computer-based reading tasks using both single-vision lenses and PAL's at an intermediate distance of 64 cm. RESULTS: Single-vision lenses performed significantly better than PAL's in one task, with a trend for better performance in another task. There was no difference in performance for the remaining two tasks. CONCLUSIONS: Visual performance tests that involved stimuli subtending the widest visual angles and demanded more fixational shifts were more sensitive in discerning performance differences between the lens designs. In general, PAL's showed marginally diminished performance compared with single-vision lenses, presumably due to their restricted intermediate channel.

Adult↗

PubMed2006

Artificial neural network discrimination of black-capped chickadee (Poecile atricapillus) call notes.

Artificial neural networks were trained to discriminate between two different notes from the "chick-a-dee" call of the black-capped chickadee (Poecile atricapillus). An individual note was represented as a vector of nine summary features taken from note spectrograms. A network was trained to respond to exemplar notes of one type (e.g., A notes) and to fail to respond to exemplar notes of another type (e.g., B notes). After this training, the network was presented novel notes of the two different types, as well as notes of the same two types that had been shifted upwards or downwards in frequency. The strength of the response of the network to each novel and shifted note was recorded. When network responses were plotted as a function of the degree of frequency shift, the results were very similar to those observed in birds that were trained in an analogous task [Charrier et al., J. Comp. Psychol. 119(4), 371-380 (2005)]. The implications of these results to simulating behavioral studies of animal communication are discussed.

Animals↗

PubMed1980

Synthesis of the contingent negative variation brain potential from noncontingent stimulus and motor elements.

Slow shifts in brain potential (commonly called the contingent negative variation), obtained during a warned reaction-time task with a foreperiod of 1 second, were compared with waveforms synthesized by the addition of separately obtained potentials associated with individual (nonpaired) sensory stimuli and self-initiated motor movements. The synthesized waveforms match closely the actual contingent negative variation, suggesting that it is constituted largely of separate, noncontingent elements related to sensory and motor processes.

Auditory Perception↗

PubMed1996

Supporting perception in the service of dynamic decision making.

Skilled performers in complex environments rely heavily on heuristic strategies to cope with the time pressure and complexity of dynamic tasks. We suggest that the use of task simplification strategies based largely on perception and pattern recognition is fundamental to the novice-expert shift in dynamic decision making. We therefore suggest that interface training interventions should support the development of highly effective and robust heuristic strategies, rather than the development of more abstract, cognitively intensive strategies. A pair of empirical studies are presented that investigated the benefits of training interventions aimed at supporting perceptual and pattern-recognitional activities in dynamic environments. Results suggest that the acquisition of skilled performance in dynamic environments can be accelerated by supporting perceptual activities in the service of dynamic decision making. Implications of these results for training, aiding, and interface design are discussed.

Adult↗

PubMed1993

Health effects of gasoline exposure. I. Exposure assessment for U.S. distribution workers.

Personal exposures were estimated for a large cohort of workers in the U.S. domestic system for distributing gasoline by trucks and marine vessels. This assessment included development of a rationale and methodology for extrapolating vapor exposures prior to the availability of measurement data, analysis of existing measurement data to estimate task and job exposures during 1975-1985, and extrapolation of truck and marine job exposures before 1975. A worker's vapor exposure was extrapolated from three sets of factors: the tasks in his or her job associated with vapor sources, the characteristics of vapor sources (equipment and other facilities) at the work site, and the composition of petroleum products producing vapors. Historical data were collected on the tasks in job definitions, on work-site facilities, and on product composition. These data were used in a model to estimate the overall time-weighted-average vapor exposure for jobs based on estimates of task exposures and their duration. Task exposures were highest during tank filling in trucks and marine vessels. Measured average annual, full-shift exposures during 1975-1985 ranged from 9 to 14 ppm of total hydrocarbon vapor for truck drivers and 2 to 35 ppm for marine workers on inland waterways. Extrapolated past average exposures in truck operations were highest for truck drivers before 1965 (range 140-220 ppm). Other jobs in truck operations resulted in much lower exposures. Because there were few changes in marine operations before 1979, exposures were assumed to be the same as those measured during 1975-1985. Well-defined exposure gradients were found across jobs within time periods, which were suitable for epidemiologic analyses.

Dose-Response Relationship, Drug↗

PubMed1990

She ate not the bread of idleness: exhaustion is related to domestic and salaried working conditions among 539 Québec hospital workers.

Hospital workers completed a questionnaire on domestic and professional working conditions and health symptoms. Workers were asked to estimate the number of domestic work hours, and the degree of sharing of laundry, cleaning, meal preparation and childcare. Responses from the 532 women workers showed an average professional work week of 31.2 hours and an average domestic work week of 19.2 hours. The length of the domestic work week increased with the number of children, and the degree of sharing diminished. Among couples with children, the reported length of the domestic work week correlated highly with an index calculated from the degree of sharing of domestic tasks, and the number and ages of children. Exhaustion and insomnia were associated with work speed and shift work, respectively, at the hospital job, but also with the number of hours of domestic work. Backache, which was related to lifting weights in the workplace, was not associated with the number of reported hours of domestic work. Due to errors in formulating some questions, the study underestimates total hours of domestic work, and, probably, effects of domestic work on health. However, it is the first North American study to show the combined effects of domestic work and paid work on physical health symptoms among women.

Adult↗

PubMed2005

The role of response selection and input monitoring in solving simple arithmetical products.

Several studies have already shown that the central executive, as conceptualized in the working memory model of Baddeley and Hitch (1974), is important in simple mental arithmetic. Recently, attempts have been made to define more basic processes that underlie the "central executive." In this vein, monitoring, response selection, updating, mental shifting, and inhibition have been proposed as processes capturing executive control. Previous research has shown that secondary tasks that require a choice decision impair the calculation of simple sums, whereas input monitoring has not been found to be a sufficient condition to impair the calculation of sums (Deschuyteneer & Vandierendonck, 2005). In the present article, we report data on the role of input monitoring and response selection in solving simple arithmetical products. In four experiments, participants solved one-digit products (e.g., 5 x 7) in a single-task, as well as in a dual-task, condition. Just as for solving simple sums, the results show a strong involvement of response selection in the calculating of simple products, whereas input monitoring does not seem to impair the calculation of such products. These findings give additional evidence that response selection may be one of the processes needed for solving simple mental arithmetic problems.

Adolescent↗

PubMed1994

Contextual influences on interactive processing: effects of discriminability, quantity, and uncertainty.

Three contextual factors--(1) the discriminability of stimuli in pitch, (2) the number of stimuli differing in pitch, and (3) the uncertainty regarding which stimuli or tasks would appear--were manipulated as subjects performed speeded loudness classifications in each of six experiments. The magnitude of Garner interference and effects of congruity were used to gauge the degree of interactive processing. Enhancing pitch discriminability caused monotonic increases in interference and congruity. Stimulus-task uncertainty mediated the changes in Garner interference wrought by increased discriminability. Uncertainty also caused a surprising shift in congruity from strongly positive to strongly negative as uncertainty grew. Increasing stimulus quantity lowered interference, but had inconsistent effects on congruity. Regression analyses suggested that, collectively, these three contextual variables underlie most failures of selective attention in speeded classification.

Adult↗

PubMedDate not supplied

Adolescent wellness: implications for effective health education programs.

Adolescence is often viewed as a period of development fraught with "problems" that need to be prevented. Problem-oriented health education often fails to serve the developmental needs of young people, thereby compromising program effectiveness. This article describes some important developmental tasks of adolescence from a wellness perspective. The effectiveness of many programs can be improved by a shift in focus from "problem prevention" to wellness promotion.

Adolescent↗

PubMed1977

An analysis of motor coordination components for various localization tasks.

Localization abilities of subjects in three perceptual-motor tasks were considered before and after an exposure to a visual distortion. During this distortion the subject observed his hand ballistically point to an invisible but audible target while either receiving or not receiving knowledge of results (KR) concerning pointing accuracy. Also, subjects either received a 1- or a 4-sec rest period between each of 30 exposure ballistic pointing actions. The pre- and postexposure tasks involved the ability of a subject to accurately point to an occluded and stationary auditory target, to point to the straight-ahead position in space, and to indicate when a moving, auditory target was perceived as being in the straight-ahead position. For these tasks, the pre- vs. postexposure localization difference scores are referred to as the negative aftereffect, the proprioceptive shift, and the auditory shift, respectively. Wilkinson's (1971) two-component additive model (negative aftereffect = proprioceptive shift plus auditory shift) held when KR was given regardless of amount of rest between exposure pointing responses. With a 4-sec rest and no KR, the relationship between coordination components was nonadditive (negative aftereffect greater than proprioceptive shift plus auditory shift).

Journal Article↗

PubMedDate not supplied

Planning and organizing a multidisciplinary psychosocial oncology service.

Providing psychosocial care to patients with cancer and their families is a formidable task given the current fiscal environment in hospitals. As the pool of available resources shrinks and populations shift from inpatient to outpatient, psychosocial staff are challenged to find creative, versatile, and efficient ways to deliver quality services and programs. This article describes the efforts to plan and implement psychosocial care at a cancer center facing the constraints of limited staff and decreasing resources. The background of the project, the development and implementation of a strategic plan, and a 1-year evaluation of the attainment of the objectives in the plan are described. The success of this approach and implications for psychosocial staff at other institutions are discussed.

Cancer Care Facilities↗

PubMed1992

Directed and divided attention in Alzheimer's disease: impairment in shifting of attention to global and local stimuli.

This study investigated the relative performance of Alzheimer's disease (AD) patients and normal controls on directed and divided attention reaction time (RT) tasks that involved the use of global-local stimuli (e.g., a large '1' made from small '2s'). Relative to normals, AD patients displayed disproportionately greater impairment on the divided attention task compared to the directed attention task. On the divided attention task, when the target remained at the same global-local level across consecutive trials, the AD patients displayed a greater facilitation effect than did the controls when responding to the second stimulus. However, when the target changed levels across consecutive trials (i.e., from the global to the local, or vice versa) the AD patients' RTs to the second stimulus were disproportionately slower than were the controls' RTs. These results demonstrated that AD patients are impaired in disengaging and shifting attention across levels of perceptual organization within the same stimulus.

Aged↗

PubMed2002

Freezing degrees of freedom under stress: kinematic evidence of constrained movement strategies.

The present study investigated the effect of psychological stress imposed on movement kinematics in a computer-simulated batting task involving a backward and forward swing of the forearm. The psychological stress was imposed by a mild electric stimulus following poor performance. Fourteen participants hit a moving ball with a horizontal lever and aimed at a distant target with as much accuracy as possible. The kinematic characteristics appearing under stress were delay of movement initiation, small amplitude of movement and low variability of spatial kinematic events between trials. These features were also found in previous studies in which the experimental task required high accuracy. The characteristic kinematics evident in the present study suggested that the movement strategies adopted by the stressed participants were similar to those that appear under high accuracy demand. Moreover, a correlation analysis between the onset times of kinematic events revealed that temporally consistent movements were reproduced under stress. Taken together, the present findings demonstrated that, under psychological stress, movement strategies tend to shift toward the production of more constrained trajectories, as is seen under conditions of high accuracy demand, even though the difficulty of the task itself does not change.

Adult↗

PubMed1985

Comparative effects of cholinergic drugs and lesions of nucleus basalis or fimbria-fornix on delayed matching in rats.

To provide a more specific test of memory impairments following lesions to central cholinergic systems, rats were trained on an operant delayed matching task. Ibotenic acid lesions of the nucleus basalis produced a disruption of performance at all delay intervals (a parallel downward shift in the delay-performance curve). By contrast, fimbria-fornix transections had no effects at short delays, but produced a progressively greater impairment as the delays lengthened (an increased downward slope of the delay-performance curve). Scopolamine produced a dose-dependent disruption of performance, apparent at the shortest delays but greater at longer delays, that was similar to the two lesion deficits combined, whereas physostigmine induced a mild but significant enhancement of performance. The results support the hypothesis that disruption of hippocampal circuitries, including cholinergic afferents via the fimbria-fornix, produces short-term or working memory impairments, whereas disruption of the cortical cholinergic system implicates more stable long-term aspects of task performance. Peripherally administered cholinergic drugs produce both types of effect and thus may influence both systems.

Animals↗

PubMed2004

Age-related changes in neural activity during visual target detection measured by fMRI.

We used functional magnetic resonance imaging (fMRI) of a visual target detection (oddball) task to investigate age differences in neural activation for the detection of two types of infrequent events: visually simple items requiring a response shift (targets) and visually complex items that did not entail a response shift (novels). Targets activated several prefrontal regions (e.g. middle frontal gyrus), as well as deep gray matter regions (caudate, putamen, thalamus and insula). Prefrontal activation was similar for younger and older adults, whereas deep gray matter activation was relatively greater for the older adults. Novels activated occipital regions (fusiform and lateral occipital gyri), and this activation was relatively reduced for older adults. The changes in behavioral performance across the task conditions were similar for the two age groups, although the older adults' responses were slower overall. Regression analyses of the relation between neural activation and task performance (response time) indicated that whereas performance was mediated most directly by prefrontal cortex for younger adults, older adults' performance was influenced to a greater extent by deep gray matter structures. Older adults may place relatively greater emphasis on the attentional control of response regulation, in compensation for the age-related decline in visual processing efficiency.

Adult↗

PubMed1992

Individual aged rats are impaired on repeated reversal due to loss of different behavioral patterns.

Aged rodents compared to young rodents are impaired in making repeated reversals and more variable in performance on many tasks. In the present study, a comparison of ten aged (21 months) and 10 young (3 months) Sprague-Dawley rats on a repeated spatial discrimination reversal water escape task revealed that the deficient and variable performance of the aged rats was due to the aged animals developing deficits in different behavioral patterns that were necessary to perform the task. Individual aged rats had deficits in inhibiting an unlearned first choice tendency (perseveration), repeating a first choice that lead to escape on the preceding trial (win-stay deficit) or inhibiting a first choice that lead to confinement and delayed escape on the preceding trial (lose-shift deficit). Because the aged animals were deficient on one or more of the necessary behavioral processes, as a group they were deficient on the repeated reversal task. However, because the aged rats differed on the specific behavioral process(es) on which they were deficient, when evaluated on any one process they were more variable than were the younger rats.

Aging↗

PubMed2001

Phase correction, phase resetting, and phase shifts after subliminal timing perturbations in sensorimotor synchronization.

Recent studies of synchronized finger tapping have shown that perceptually subliminal phase shifts in an auditory sequence are rapidly compensated for in the motor activity (B. H. Repp, 2000a). Experiment 1 used a continuation-tapping task to confirm that this compensation is indeed a phase correction, not an adjustment of the central timekeeper period. Experiments 2-5 revealed that this phase correction occurs even when there is no ordinary sensorimotor asynchrony--when the finger taps are in antiphase or arbitrary phase relative to the auditory sequence (Experiments 2 and 3) or when the tap coinciding with the sequence phase shift is withheld (Experiments 4 and 5). The phase correction observed in the latter conditions was instantaneous, which suggests that phase resetting occurs when the motor activity is discontinuous. A prolonged phase shift suggestive of overcompensation was observed in some conditions, which poses a challenge to pure phase correction models.

Acoustic Stimulation↗