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PubMed1990

Cognitive and affective disorders in elderly diabetics.

In non-insulin-dependent diabetes mellitus, performance of complex cognitive tasks requiring the storage and retrieval of new information is poorer than in age-matched controls. By contrast, performance of less demanding tasks such as immediate memory and simple reaction time is essentially equivalent for NIDDM patients and controls. This pattern parallels the cognitive change observed with normal aging, in which age differences are minimal on less demanding immediate memory tasks but older adults perform more poorly than young adults on secondary or long-term memory tasks. Age-related changes in cognitive performance have been attributed to a reduction in processing resources or working memory capacity. Although the explanation for NIDDM-related deficits remains to be identified, reduced glucose control and elevated levels of triglycerides appear to play some role in cognitive impairment. Non-insulin-dependent diabetes is associated not only with elevated levels of depression, but with an increased frequency of self-reported memory problems. Moreover, elevated levels of depression are associated with various indicators of neuropathy and with significant reductions in self-regulated control of glucose at the time of medical office visits. Diabetic patients may perceive less control over their lives as a result of the many restrictions associated with the disease. When provided with the opportunity to exercise control, however, performance on many cognitive tasks can be improved in NIDDM as well as in age-matched controls. This suggests that by providing NIDDM patients with opportunities to exercise increased control over their lives it may be possible to enhance motivation and to increase the likelihood of the patient's adopting more effective self-regulatory behaviors.

Aged↗

PubMed1991

Visual speech processing: word-decoding and word-discrimination related to sentence-based speechreading and hearing-impairment.

Two aspects of visual speech processing in speechreading (word decoding and word discrimination) were tested in a group of 24 normal hearing and a group of 20 hearing-impaired subjects. Word decoding and word discrimination performance were independent of factors related to the impairment, both in a quantitative and a qualitative sense. Decoding skill, but not discrimination skill, was associated with sentence-based speechreading. The results were interpreted such that, in order to represent a critical component process in sentence-based speechreading, the visual speech perception task must entail lexically induced processing as a task-demand. The theoretical status of the word decoding task as one operationalization of a speech decoding module was discussed (Fodor, 1983). An error analysis of performance in the word decoding/discrimination tasks suggested that the perception of heard stimuli, as well as the perception of lipped stimuli, were critically dependent on the same features; that is, the temporally initial phonetic segment of the word (cf. Marslen-Wilson, 1987). Implications for a theory of visual speech perception were discussed.

Adult↗

PubMed1991

Dual-task assessment of reorganization of postural control in persons with lower limb amputation.

Postural control in persons with lower limb amputation was studied using a cognitive approach to motor learning. The aim of this study was to show that an important characteristic of the central reorganization process after a lower limb amputation is the gradually decreasing need of attentional resources to perform a motor task. A dual-task procedure was developed to estimate the level of automaticity of a quiet, upright standing task. The effect of a concurrent attention-demanding task (Stroop task) on the efficiency of balance control was determined using force-platform measurements at the start and the end of the rehabilitation process. In contrast with a control group, the amputation group showed interference effects on body sway caused by the concurrent task both at the start (p less than .05) and, less severe, at the end of rehabilitation (p less than .05). Improvement of balance control was significant only for the dual-task condition (p less than .05). The results corroborated the hypothesis that dual tasks give information about the restoration of automaticity of postural control as an essential characteristic of the central reorganization process in persons with lower limb amputation. The role of dual-task procedures as a useful approach to skill assessment is discussed.

Adult↗

PubMed1983

Task complexity and problem-solving performance in younger and older adults.

In problems resembling the Twenty Questions game, older and younger adults were asked to discover the square or squares the experimenter had in mind from an array of squares. Complexity was varied in three conditions in which problems had 6, 8, or 12 bits of information. Task demands were increased in a fourth condition by imposing a 60-sec time limit. Contrary to a hypothesis drawn from prior results, no evidence was found that older adults select more efficient strategies as task complexity or demands increase. Both age groups maintained the same strategies; the less efficient strategies selected by the older persons were reduced in effectiveness as task complexity increased.

Adolescent↗

PubMed1995

Positron-emission tomography studies of cross-modality inhibition in selective attentional tasks: closing the "mind's eye".

It is a familiar experience that we tend to close our eyes or divert our gaze when concentrating attention on cognitively demanding tasks. We report on the brain activity correlates of directing attention away from potentially competing visual processing and toward processing in another sensory modality. Results are reported from a series of positron-emission tomography studies of the human brain engaged in somatosensory tasks, in both "eyes open" and "eyes closed" conditions. During these tasks, there was a significant decrease in the regional cerebral blood flow in the visual cortex, which occurred irrespective of whether subjects had to close their eyes or were instructed to keep their eyes open. These task-related deactivations of the association areas belonging to the nonrelevant sensory modality were interpreted as being due to decreased metabolic activity. Previous research has clearly demonstrated selective activation of cortical regions involved in attention-demanding modality-specific tasks; however, the other side of this story appears to be one of selective deactivation of unattended areas.

Brain↗

PubMed1990

Changes in spontaneous EEG activity indicate a special kind of information processing in concept learning.

Some findings in the literature suggest that a high amount of spectral power in spontaneous EEG alpha 1 band (7.5-10.0 Hz) may be associated with tasks demanding extensive monitoring of stimulus information and combining features for a match with internal concepts ("exploration"). EEG recordings were obtained from 9 subjects involved in a concept-learning task. They had to match visually presented objects with a concept built up by hypothesis and to respond by pressing a "yes" or "no" key. Epochs of EEG data were analyzed with epoch center-times at 500 and 250 ms before response execution. In the case of "yes" responses, when subjects could match their hypothesis positively with combined features of the presented object increased alpha 1 spectral power was found. Also alpha 1 power was larger immediately after disconfirming feedback than after confirming feedback. Additionally, alpha 2 spectral power (10.5-12.5 Hz) was found to be larger 250 ms after confirming feedback than after disconfirming feedback. It is argued that alpha 1 power seems to reflect those mental processes which are involving in combining features and matching them to a concept in mind. The increase in alpha 2 power after confirming feedback is interpreted in terms of general processing demands imposed during task performance.

Adult↗

PubMed1998

Lingual action in normal sequential swallowing.

Current knowledge about the flexibility in lingual motor control and performance during swallowing is incomplete. The present study aimed at gaining a better understanding of the tongue's motor flexibility and at identifying variable versus invariant lingual motor program parameters in light of changing swallowing task demands (discrete vs. sequential). Specifically, the timing and patterns of tongue-palate contact and the associated changes in tongue shape and action were examined in 5 normal adults using simultaneous electropalatography and ultrasound. Tasks for discrete swallowing included 5 and 30 cc of water; tasks for sequential swallowing involved drinking 200 cc of water at normal and fast rates. Results showed little variation in propulsive contact pattern as a function of task or subject. However, the tongue demonstrated shorter movement duration and overlapping gestures during sequential swallowing. Thus, continuous drinking was performed without changes in motor strategies per se but with changes in the timing coordination of the "drink" and "swallow" action sequences. These findings support the theory that the deglutitive lingual motor program has both invariant and variant parameters, and that movement pattern and action sequence reflect fixed elements within the structure of the motor program, but movement timing can be modified according to the demands of the task at hand.

Adult↗

PubMed1997

Attention and somatic awareness in chronic pain.

Empirical methods are used to explore the relationship between chronic pain, somatic awareness and attention. Using a primary task paradigm, 46 chronic pain patients performed an attentionally demanding task. Patients were classified according to self reported pain intensity and the extent of their reporting of the perception of bodily sensations (somatic awareness). Results showed that, as predicted, disruption of attentional performance was most pronounced in those who reported high pain intensity and high somatic awareness. Further analysis revealed that these patients also reported high negative affect. These findings are discussed in terms of their theoretical implications for the concept of hypervigilance and their clinical implications for chronic pain control.

Adult↗

PubMed1982

[Ergonomic strain measurement in text processing].

Text processing task demands are analysed by using an Ergonomic Job Description Questionnaire. The tasks are classified by cluster analysis. Tasks out of each cluster are examined with respect to performance and physiological strain by 8-h measurements. These reactions are assessed in terms of tolerance limits and the distribution of demands is discussed for non-tolerable work conditions.

Female↗

PubMed1988

Assessing the development of automatic processing: an application of dual-task and event-related brain potential methodologies.

Previous research has found that properties of automatic processing do not always co-occur, suggesting that the acquisition rates may differ. The present study investigated the acquisition rate of several of these properties by employing additive factors logic, dual task methodology, and event-related brain potentials. Seven subjects participated in a ten session experiment in which they performed two tasks, a visual/memory search task and a pursuit step tracking task, both together and separately. RT and P300 latency measures indicated that parallel processing of the display was achieved early in training in the consistent mapping condition. This processing was unaffected by dual task demands. An analysis of RT/P300 ratios suggests that another form of perceptual efficiency was achieved later in practice in both the varied and consistently mapped search tasks. This effect was larger in the consistent mapping condition. Reductions in the slope of the memory set function occurred significantly earlier for P300 latency than for RT, suggesting that the stimulus evaluation processes became automated more rapidly than the response selection components of memory search. Consistent with an analysis of the processing demands of the two tasks, the introduction of the tracking task and an increase in tracking difficulty produced equivalent interference during consistent and varied mapping conditions. Results are discussed in terms of models of skill, skill acquisition and component task automaticity.

Adult↗

PubMed1990

Phonological and motoric demands in handwriting: evidence for discrete transmission of information.

In an experiment with handwriting tasks effects of phonological and motoric task factors upon reaction time and movement time were measured to test implications of a discrete information processing account of the task. The model is built up of serially organized stages, each of which monitors one specific type of operation, necessary to generate a message. The serial structure of the model is defined as the limitation that higher levels of the model provide their output to the next lower processor in the hierarchy, and receive their input from the next higher stage. The parallel character of the model is exemplified through the assumption that all processors are active at the same time and concurrently with the real time production of writing movements. The study adds evidence that a serial architecture of processors can be compatible with the parallel processing of a message as long as more abstract operations are prepared more in advance to real-time movements than operations lower in the hierarchy. In the experiment the prediction was tested that the time course of the manifestation of phonological and motoric task demands reflects the discrete and serial structure of the model.

Adult↗

PubMed1995

Chronic pain and distraction: an experimental investigation into the role of sustained and shifting attention in the processing of chronic persistent pain.

Although there is anecdotal evidence for the psychoanalgesic properties of distraction, research evidence is equivocal. Drawing on the clinical and experimental studies of attention-based coping strategies for pain control, and the theoretically driven 'cognitive' models of the human attention system, two experiments are reported. Experiment One demonstrates that chronic pain patients suffering high intensity pain show significantly impaired performance on an attentionally demanding task when compared to low pain patients and normal controls. Experiment Two tests the hypothesis that the low intensity pain patients in Experiment One are coping with the dual demand of processing the pain and processing the task by switching quickly between these attentional demands. The results of both experiments are discussed in terms of the evidence for the analgesic properties attention based coping strategies with clinical pain populations and re-addresses the literature on coping with pain in terms of cognitive theories of attention.

Adaptation, Psychological↗

PubMed1995

Favor referential representations.

Avrutin and Hickok (1993) argue that agrammatic patients have the ability to represent nonreferential or "government" chains ("who ... e") but not referential or "binding" chains ("which girl ... e"). By contrast, we propose the "referential representation hypothesis," which suggests that agrammatics attempt to cope with their well-known capacity limitations by favoring referential or content-based representations. This predicts that agrammatic patients' performance should degrade noticeably as task demands increase, and referential demands should take priority over computational ones. In a semantic task, referential phrases should lead to better or more accurate performances. In syntactic tasks, the availability of a referential or content-based representation will interfere with the development of a syntactic representation, resulting in worse syntactic performance on the referential phrases than on nonreferential ones. This predicts that agrammatic patients should incorrectly accept (resumptive) pronoun sentences with a referential wh-phrase because the pronouns will find the semantic or discourse referent of the referential wh-phrase and take it as an antecedent for the pronoun. However, they should reject a (resumptive) pronoun in a sentence with the nonreferential question constituent "who" or "what." "Who" and "what" will remain in syntactic form, since they have only grammatical content and therefore will have only a "nonreferential" syntactic representation. Consequently, they cannot serve as the antecedent of the pronoun. These predictions were largely confirmed by the results of a grammaticality judgement study. Agrammatics performed well on questions with pragmatic biases but failed to distinguish reliably between grammatical and ungrammatical questions where pragmatic biases were neutralized. They assigned especially low ratings to object gap sentences with referential wh-constituents, as predicted. They assigned relatively high ratings to ungrammatical subject pronoun sentences with either type of wh- constituent. The agrammatics accepted ungrammatical reflexive sentences even though syntactic number and gender features alone could have been used to correctly judge the sentences. We attribute this, too, to the unavailability of a reliable syntactic representation of those phrases with referential or extragrammatical semantic content.

Adult↗

PubMed1996

Orthographic processing in visual word recognition: a multiple read-out model.

A model of orthographic processing is described that postulates read-out from different information dimensions, determined by variable response criteria set on these dimensions. Performance in a perceptual identification task is simulated as the percentage of trials on which a noisy criterion set on the dimension of single word detector activity is reached. Two additional criteria set on the dimensions of total lexical activity and time from stimulus onset are hypothesized to be operational in the lexical decision task. These additional criteria flexibly adjust to changes in stimulus material and task demands, thus accounting for strategic influences on performance in this task. The model unifies results obtained in response-limited and data-limited paradigms and helps resolve a number of inconsistencies in the experimental literature that cannot be accommodated by other current models of visual word recognition.

Adult↗

PubMedDate not supplied

Branched-chain amino acid supplementation during 30-km competitive run: mood and cognitive performance.

It has been suggested that an elevated concentration of the neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) in specific areas of the brain may contribute to the development of central/mental fatigue during and after sustained exercise. Supplementation with branched-chain amino acids (BCAAs) should prevent the exercise-induced increase in the plasma concentration ratio of free tryptophan to other large neutral amino acids (including BCAAs) and thereby prevent an elevation in the level of 5-HT in the brain. In this study, subjects were given either a mixture of BCAAs in a carbohydrate solution or a placebo drink that contained only carbohydrates during a 30-km cross-country race. Several tasks to measure cognitive performance were performed before and after the race. When subjects were supplied with BCAAs, their performance in the different parts of the color-word test (words, colors and color words) was improved by an average of 3-7% (p < 0.05) after exercise, whereas there was no difference in performance before and after exercise in the subjects who were given the placebo. Furthermore, the experimental group, supplied with BCAAs, maintained their performance in the shape-rotation and figure-identification tasks, whereas an impairment in performance in these tests by 25% (p < 0.05) and 15% (p < 0.05), respectively, was found in the subjects who received the placebo. Thus, BCAA supplementation seemed to have an effect on the more complex tasks, whereas no effect could be detected on the less demanding tasks. However, an intake of BCAAs during exercise modified only slightly the exercise-induced changes in mood.

Adult↗

PubMed1989

Human brainstem auditory evoked potentials fail to provide evidence of efferent modulation of auditory input during attentional tasks.

Efferent modulation of auditory input at the level of the brainstem during attention-demanding tasks has been described in animal studies. Attempts to demonstrate these effects in humans have produced conflicting results, however. These studies are reviewed with particular reference to those animal experiments that have demonstrated peripheral effects. The human experiments have used a number of attentional conditions which have not been related either to each other or to the successful animal work. Two of the most important conditions in these studies--the use of an intermodal attention task and the manipulation of attentional states--have been examined rarely or not at all in the human research. Two experiments were conducted to investigate the possibility of attention-related effects on the human brainstem auditory evoked potential. These experiments were designed to examine experimental conditions common to both successful and unsuccessful attempts to demonstrate attention-driven efferent modulation at the periphery in humans. Also examined was the gradation of attention effects on efferent modulation demonstrated in animals but never studied in humans. No significant changes in either the latency or the amplitude of the brainstem auditory evoked potential were found in any of the attention-demanding conditions. Results are discussed in terms of psychophysiological theories of attention. Also, the interpretation of the most recent animal work is questioned.

Adolescent↗

PubMed1989

Contextual information and temporal terms.

We report an experiment designed to identify how contextual information can influence children's performance on an experimental task involving temporal terms. Crain (1982) reported improved performance on a comprehension task when subjects were provided with contextual information, and he suggested that the improvement was due to satisfaction of presuppositions. However, this contextual information might have served to simplify task demands by providing prior information concerning an important aspect of the task. The present study distinguishes these factors by incorporating contextual information into the subordinate clause of the test sentences in a comprehension experiment (to satisfy presupposions) or into the main clause (to provide comparable prior information without satisfying presuppositions). We conclude that contextual information results in a significant improvement only when such information can be used to satisfy presuppositions.

Child Language↗

PubMed1994

Psychology of computer use: XXXII. Computer screen-savers as distractors.

The differences in performance of 16 male and 16 female undergraduates on three cognitive tasks were investigated in the presence of visual distractors (computer-generated dynamic graphic images). These tasks included skilled and unskilled proofreading and listening comprehension. The visually demanding task of proofreading (skilled and unskilled) showed no significant decreases in performance in the distractor conditions. Results showed significant decrements, however, in performance on listening comprehension in at least one of the distractor conditions.

Adolescent↗