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At least 793 records · Page 44Linked to original sources

PubMed1994

The effects of two matched memory tasks on concurrent finger tapping.

In a dual task experiment, subjects were instructed to perform a single finger tapping task whilst either, concurrently memorizing words appearing randomly on a screen in front of them, or concurrently memorizing the positions of the words. Analysis of percentage change scores revealed a significant tapping hand by task interaction; subjects showed a significantly larger left- than right-hand decrement when the task required memorizing the positions of the words and a non-significantly larger right- than left-hand decrement when the task required memorizing the words. These results suggest that the nature of the task demands determined the pattern of interference observed.

Attention↗

PubMed1990

Behavioral performance effects of nicotine in smokers and nonsmokers.

Performance on finger-tapping and handsteadiness, tasks opposite in response requirements, was compared between male smokers and nonsmokers (n = 10 each) on two occasions, once following intake of nicotine (15 micrograms/kg) by measured-dose nasal spray and once following placebo. Compared with nonsmokers, smokers had significantly greater increase in finger-tapping speed due to nicotine. On the other hand, smokers tended to have improved performance on handsteadiness (i.e., less involuntary movement) due to nicotine, while nonsmokers had impaired performance, although this difference was not significant. Nicotine-induced changes in performance on each task were inversely related, suggesting specificity of the behavioral effects of nicotine depending on task demands, rather than a generalized effect. These effects of nicotine on behavioral performance may be important in understanding the reinforcing value of nicotine intake, and differences in effects as a function of smoking history may suggest chronic adaptation to nicotine.

Adult↗

PubMed1984

Phencyclidine (PCP): some human studies.

Studies on the effects of PCP have been conducted in volunteers in the Army Laboratories and elsewhere and in illicit users. The present review has summarized the observations of many investigators which showed that the acute effects of PCP following several routes of administration were shown to be dose-related. High doses of PCP produce disturbing manifestations including psychosis, numbness, light-headedness, vertigo, ataxia, and nystagmus due to acute intoxication. Furthermore, some subjects became irritable, argumentative or negative under the conditions of social stress and demanding tasks. In addition to a variety of central action, PCP has also been shown to affect cardiovascular function, heat storage, and exercise performance. PCP can also induce, although rarely, prolonged toxic psychosis in chronic abusers and precipitate psychotic episodes in psychotic and prepsychotic personalities. Tolerance, but not physical dependence, develops to the effects of PCP. Psychologic dependence as indicated by craving for the drug has however been reported.

Administration, Oral↗

PubMedDate not supplied

The relationship of patient difficulty to therapist performance in interpersonal psychotherapy of depression.

The efficacy of Interpersonal Psychotherapy (IPT) in the treatment of ambulatory major depression was demonstrated in the recently completed NIMH Treatment of Depression Collaborative Research Program (Elkin et al. 1986). Factors which enhance or impede the administration of the treatment delimit effective patient care and should therefore be understood. This report examines the relationship of pretreatment patient attitudes and in-treatment patient difficulty to the ability of therapists to competently conduct IPT, using data from a training program in IPT. The hypothesis was that the patient's ability and willingness to establish a relationship and undertake the task demands of therapy would influence the therapist's ability to administer treatment. Patient difficulty was found to be strongly related to both therapists' and supervisors' judgements of therapist performance during IPT sessions: when patients were more difficult, therapists were judged to have performed more poorly. Patients' preexisting negative expectations about the potential outcome of treatment were associated with patient difficulty and poorer therapist performance, while the level of presenting symptomatology was not. Thus, it appears that the patient's ability to engage in a productive therapeutic relationship rather than the severity of his presenting problems influenced the therapist's ability to competently perform IPT. The findings regarding the relationship of patient difficulty to ratings of therapist performance suggest that patient difficulty should be taken into account in assessing therapist competence, whether for studies of therapeutic efficacy or for clinical supervision and training in general.

Adult↗

PubMed1983

Personality style differences in visual search performance.

The present study continues the examination of the personality styles in normal populations that have been described in the clinical literature. Earlier work has focused on behavioral, attitudinal, and cognitive components of the personality styles. The present study extends our exploration of the cognitive domain by examining the performance of different personality groups on a visual scanning task. Hysterics searched a stimulus array for letter targets at a mean rate of 0.04 +/- SD 0.177 seconds per unit of information, which was slower than the control rate of 0.0225 +/- SD 0.0078 seconds. The results indicated that hysterics used a serial search strategy to compensate for an inability to process information efficiently and thus differed from compulsives who conformed to task demands and performed similarly to controls.

Achievement↗

PubMed1987

Effects of instructions on habituation of the orienting response: another perspective on the study by Gruzelier and Eves.

A recent study by Gruzelier and Eves (1987, Int. J. Psychophysiol., 4: 289-291) purported to test the hypothesis of Iacono and Lykken (1979, Schizophrenia Bull., 5: 11-14), that instructions to subjects that clarify task demands facilitate habituation. However, the Gruzelier and Eves study did not provide an adequate test of this hypothesis. Moreover, contrary to the assertions of Gruzelier and Eves, the data presented in their paper are consistent with the predictions of Iacono and Lykken.

Acoustic Stimulation↗

PubMed1987

Rate of habituation of electrodermal orienting responses: a comparison of instructions to stop responding, count stimuli, or relax and remain indifferent.

Thirty-nine subjects listened to two series of repetitive tones, the second series of which was of higher or lower pitch and of higher intensity. Before the first series all subjects were given conventional instructions to relax and adopt a passive attitude to the tones. Before the second tone series one of three instructions was given: to maintain a relaxed and passive attitude, to inhibit responding, to count the stimuli silently. The three groups showed roughly equivalent rates of habituation to the first tones series but the group instructed to count the tones showed slower habituation than the groups instructed to remain indifferent or to inhibit responses. A recommendation to clarify task demands in habituation experiments, by informing subjects that the aim was to see how quickly subjects stopped responding, showed no advantages over conventional instructions.

Adult↗

PubMed1989

Eye movements and blinks: their relationship to higher cognitive processes.

Information about the timing of spontaneous eye blinks was abstracted while subjects performed a detection and identification task. We found blinks to be time-locked to saccadic eye movements involved in the identification of peripherally presented stimuli. The larger the required eye movement, the greater the likelihood of blink occurrence. Blink latencies were found to be significantly shorter for centrally, as compared to peripherally presented stimuli, and blinks were more likely to be associated with eye movement returning gaze to a central location than with movements associated with the identification of peripherally presented information. Thus, we conclude that the spontaneous or endogenous eye blink is triggered by aspects of information processing, and that blink latencies can be used as one tool for evaluating the level of complexity of such processing under a wide variety of task demands.

Blinking↗

PubMed1992

Active and passive P3 latency and psychometric performance: influence of age and individual differences.

The relationship of P3 latency of the event-related potential (ERP) to psychometric performance was investigated in 41 subjects who ranged in age from 20 to 88 years. P3 responses were recorded from subjects using an auditory oddball paradigm with and without task-demands. Subjects also received psychometric tests of verbal performance, visuospatial performance, concentration, and immediate, recent and remote memory. Factor analysis was used to reduce the set of psychometric measures to four factors (Verbal learning, general intelligence, narrative recall/fluency, and concentration). Both passive and active P3 latency showed a linear increase with age. Age was inversely correlated with verbal learning performance. After accounting for the influence of age, passive P3 latency correlated with the psychometric factor associated with narrative recall and verbal fluency. Active P3 latency was correlated with factors reflecting general intelligence and concentration. These findings suggest that cognitive processing speed contributes to psychometric performance in adults. The psychological or biological basis for this relationship remains to be identified.

Adult↗

PubMed1994

Task-induced differential cortical activation pattern.

Measures of task-dependent cortical activation were assessed by bilateral EEG recordings from frontal, temporal, parietal and occipital areas. Two pictorial tests, the Raven Advanced Progressive Matrices and the Space Relations Test were used for verbal and spatial conditions, respectively. Recordings were obtained for 20 trials of each task from 22 right-handed adult males and 16 s. trial epochs were subjected to Fast Fourier analyses. Averaged intensity values for the alpha band were compared between verbal and spatial tasks for all subjects and between subgroups of verbalizers and visualizers, allotted on the basis of subject's performance index, derived from response speed and accuracy on the two tasks. The results were as follows: (1) The most pronounced EEG discriminators between the two performance subgroups are the left and right parietal and the right frontal area; (2) The left parietal zone provides the most pronounced discrimination between two groups; (3) There were significant interactions between the left parietal and the right frontal region; (4) The two parietal areas show characteristic frequency shifts in opposite directions for the task conditions. The findings imply complex interplay among the two parietal and right frontal areas, associated with sequential and holistic strategies. The results urge researchers to take into consideration subjectively preferred cognitive strategy, which along with objective task demands influences the process of problem solving and accompanying physiological changes.

Adult↗

PubMed1996

Attention-induced neuronal activity in the monkey somatosensory cortex revealed by pupillometrics.

Detection of a sensory stimulus is facilitated when attention is directed towards the stimulus source. Neuronal substrates for this psychological effect were studied in monkeys performing an attention-demanding task, by simultaneous recording of neuronal activity and pupillary dilation as an indicator of attentive state. We found that neurons in the postcentral somatosensory cortex (SI) started to discharge concurrent with the pupil dilation onset which occurred well before the somatosensory stimulus. Neuronal firing rates were positively correlated with the degree of dilation, suggesting that the SI neural activity is under the direct influence of the attentional process.

Animals↗

PubMed1994

Use of indirect conductimetry to predict the growth of spoilage yeasts, with special consideration of Zygosaccharomyces bailii.

In recent years, modeling for the purpose of predicting microbiological spoilage of foods has gained much interest. Predictive modeling requires a concentrated mathematical and experimental approach; to collect data of adequate quality is a technically demanding task when several experimental parameters are involved. Rapid, non-traditional, automated techniques are particularly useful in modeling. Of these, electrometric techniques appear to be most promising. Indirect conductimetry was used to study the effect of temperature, aw, pH and potassium sorbate concentration on the growth of Zygosaccharomyces bailii. The automated Malthus 2000 instrument proved to be convenient for gathering a large amount of data that were then used to develop polynomial models describing the response of the yeast to combinations of experimental factors in terms of conductimetric detection time and maximum rate of change in conductance. Results demonstrated that indirect conductimetry is suitable for monitoring the effect of environmental factors on the growth and activity of Z. bailii and perhaps other food spoilage yeasts.

Conductometry↗

PubMed1984

Clinical application of the P3 component of event-related potentials. II. Dementia, depression and schizophrenia.

Patients with dementia, schizophrenia and depression were tested with analogous auditory and visual event-related potential (ERP) paradigms designed to elicit a large P3. The patient groups were compared to age normative predictions derived from a large control sample for a number of ERP and behavioral variables. The results were similar for the auditory and visual paradigms. P3 latency was prolonged two or more S.D.s beyond that predicted by age for less than one-half of the demented patients. This latency prolongation was significant for the group as a whole but would result in too many false negatives if used diagnostically for individuals. Furthermore, increased P3 latency was not specific, as the schizophrenic patients also had later P3s. The amplitude of P3 was reduced in the demented patients, but it was also smaller in other patient groups. The only variable which distinguished the demented patients from both controls and from the other patients was the single trial P3 latency/RT correlation. The demented patients, as a group, had significantly lower P3 latency/RT correlations, but this effect also was not sensitive enough to be diagnostic for individuals. The data from these two paradigms suggest that the P3 amplitude and latency abnormalities observed reflect a common, rather than a diagnostically specific deficit. This study is in contrast to some others which report much more sensitivity and specificity in the use of P3 latency in the diagnosis of dementia. Differences in task demands, patient samples and ERP analysis techniques might explain some of the discrepancy.

Auditory Perception↗

PubMed1995

National infrastructures for delivery of hepatitis B vaccination to different age groups.

If hepatitis B vaccination is to be introduced into a universal vaccination programme, it must be given before young people become sexually active. Two age groups are of main interest: infants and early adolescents. In Australia, North America and Europe, vaccination programmes for infants are well established but not yet for adolescents. From a developmental point of view, targeting adolescents seems to be a demanding task. Nevertheless, there are examples of successful approaches: e.g. rubella vaccination in the UK, where since its introduction in 1976 the immunization coverage among 14-year-olds has remained high at 80-85%, or the more recent hepatitis B strategies in Italy and Spain, where young adolescents are included with high success rates. In summary, whereas the inclusion of HBV vaccine in the infant immunization programme is not a problem in most counties, the approach to adolescents needs more thought.

Adolescent↗

PubMed1992

A study of some mechanical properties of an RTV polydimethylsiloxane for extraoral maxillofacial prostheses.

The construction of facial prostheses simulating the missing tissues as closely as possible is an imperative and demanding task. Such prostheses will be comprised of parts presenting different mechanical properties attempting to simulate facial tissues. In this study the mechanical properties of a room temperature vulcanized (RTV) silicone facial elastomer were modified, altering the molecular architecture by controlling the amount of cross-linking. A wide range of compliance was achieved which enables more lifelike facial prostheses to be made in clinical practice.

Cross-Linking Reagents↗

PubMed1994

Evaluation of experimental and finite element models of synthetic and cadaveric femora for pre-clinical design-analysis.

The aim of this study was to determine the validity with which the finite element method could model synthetic bone and thereby determine the appropriateness of such femur analogues for application in pre-clinical tests. The performance of these synthetic femora was compared with cadaveric bone when employing the same geometric and material definition protocols. A four-point bend loading configuration was selected for this analysis. Four synthetic femurs and an embalmed cadaveric bone were tested experimentally to determine the structural bending stiffness (k) for the diaphysis of these bones. A finite element (FE) model was generated and an analysis performed for each bone type to estimate the Young's modulus (E) required to obtain a model stiffness equivalent to that obtained experimentally. The estimated material elastic modulus in the FE model for the synthetic femur was found to be very similar to available data for this bone analogue. The estimated cadaveric bone modulus however was found to differ significantly from documented values for cortical bone. A theoretical analysis demonstrated the great sensitivity of the estimated modulus value to the accuracy of the geometric definition. The very low variability found in the experimental test on the synthetic bones together with their more regular geometry and the possibility of achieving greater accuracy in geometric definition was shown to enable the production of a valid FE model of this bone for an isotropic homogeneous material description. Conversely, the greater irregularity of geometry, together with the less obvious differentiation between the cortical and cancellous bone in the cadaveric specimen makes accurate geometric description of this bone very difficult. This fact, together with the uncertainty concerning the quality of the cadaveric bone and its viscoelastic response during mechanical testing, makes reproduction of its behaviour in a FE model a much more demanding task. It is suggested that this greater capability of reproducing the experimental behaviour of the synthetic bone makes them a very useful model for both experimental and numerical studies which involve in-vitro pre-clinical testing of implant design and stem-bone behaviour.

Artificial Organs↗

PubMed1983

Task determinants of ear differences in melody processing.

In Experiment 1 nonmusicians were presented with dichotic melodies, which differed either on all pitches or by a single note, followed by a set of four binaural melodies. They were asked to recognize among the alternatives only one member of the dichotic pair in the "single-focus" task, and both dichotic melodies in the "double-focus" task. These different attention requirements led to a LEA in the first task which contrasted with the REA observed in the other task when melodies differed by all pitches. A possible confounding (fusion of the common pitches) prevents comparison of the tasks for melodies differing by a single pitch. The role of the extent of melody differences was further investigated in a second experiment by changing melodies on one, two, or three notes. No effect of material was observed on ear asymmetries. Task demands appeared as the most critical determinant of ear differences and are discussed in terms of their particular influence on the adoption of an analytic or holistic processing mode. Male subjects were found to be more responsive than females to analytic processing suggestions.

Adult↗

PubMed1986

The lateralization of lip-read sounds: a first look.

Two tachistoscopic studies on the lateralization of lip-read still photographs in normal right handers are reported. In the first, subjects matched a still lip photograph with a heard speech sound. A clear right hemisphere (LVF) advantage emerged, despite the phonological requirements of this task. This pattern of laterality failed to interact with the type of response (same/different) or with the status of the heard phoneme; both consonant and vowel matching showed the same pattern of LVF advantage, despite the significantly greater difficulty of consonant than vowel matching in this particular task. In the second study subjects were required to speak the sound they saw being spoken by a centrally displayed face photograph. The displayed face was chimeric; that is, one side of the face was seen saying one sound, one side another. Here, a rather complex pattern of results ensued. For the speakers seen a clear expressor asymmetry emerged; speech sounds were judged more accurately when they issued from the right side of the speaker's face. However, in the LVF, and only the LFV, accuracy in reporting chimeric face sounds correlated with speed in learning to lip-read, suggesting that the LVF is systematically involved even when task demands (speaking the response, phonological analysis, small, more central displays) do not, at first sight, suggest that they should. Taken together, these studies suggest that the right hemisphere could support some aspects of the processing of seen speech in normally hearing, normally lateralized individuals.

Adolescent↗