Cognitive Task Demands Research Articles

Discrimination learning requiring different memory components in rats: age and neurochemical comparisons.

The performances of young (8-9 months) and aged (22-24 months) male ACI rats were compared in a T-maze requiring two discriminations, each of which placed different demands on memory processing. A spatial discrimination in the stem of the T-maze required long-term reference memory; a discrete-trial, alternation discrimination in the arms of the T-maze required working memory. Following acquisition training in one maze, rats were also trained in a second maze at a different location in the room. The correct response in the stem of this maze was opposite to that in the first maze. In two experiments with slightly different pretraining procedures, similar results demonstrated that aged rats made more errors in all phases of maze training than did their young counterparts. The results suggest that all components of memory processing were affected equivalently because the age-related impairment was not selectively greater in any component of the task. In a third experiment, aged rats were unimpaired in the ability to perform in a T-maze task involving a brightness discrimination with intramaze cues. This result suggests that the age-related impairment in the two-component T-maze task was restricted to the cognitive demands of the task. Neurochemical analyses were performed to determine whether regional neurotransmitter synthetic enzyme activities could be used to identify neurochemical systems associated with performance in these tasks and with any age-related impairments observed. Choline acetyltransferase and glutamic acid decarboxylase were assayed as markers for cholinergic and GABAergic systems, respectively, in the hippocampi and the following cortical regions: frontal, sensorimotor, auditory, cingulate, occipital, and pyriform-perirhinal. A slight (8%) but significant age-related decline was observed in the activity of glutamic acid decarboxylase but not of choline acetyltransferase. Although the correlation between maze performance and regional enzyme activities generally supported several previous observations, the only significant correlation to emerge was between working memory performance and glutamic acid decarboxylase activity in the cingulate cortex.

The effects of cognitive task demand on subjective stress and blood glucose levels in diabetics and non-diabetics

Blood glucose levels (BGLs) and subjective estimate of stress levels (SESLs) were measured repeatedly in 45 min baseline sessions on three successive days in insulin-dependent diabetic and non-diabetic groups. In the diabetic groups the initial level of BG was twice that of the non-diabetic group and BGLs declined steadily within each session but not across sessions whereas BGLs in the non-diabetic group remained steady both within and across sessions. On two subsequent days half of each group performed a high demand and half a low demand task, BGLs and SESLs being assessed before, during and after the stress period. Stress did not appear to induce significant changes in BGL in any of the groups even though SESL measures indicated that the task appeared stressful to the groups. The implications of these findings for the relationship between stress and increases or decreases in BGL are discussed.

Effects of spaced and repeated total sleep deprivation.

Abstract Six young adult males were sleep deprived for 2 nights on five successive occasions at 3 week intervals. During the deprivation period they completed subjective ratings and performed on an extensive battery of tasks. Subjective measures and vigilance tasks showed substantial deprivation effects; the cognitively-demanding tasks were less affected. Where repetition of sessions resulted in changes, relative to sleep deprivation the effects were those of ‘sensitization’ rather than ‘immunization’.

The relationship of extraversion and neuroticism with job preferences and job satisfaction for clerical employees

A field study was conducted with 175 Civil Service clerical employees. The results indicated that extraverts preferred jobs with higher levels of cognitive task demands, pace of task demands, cognitive closure, extrinsic rewards and intrinsic rewards. Neuroticism was negatively related to these preferences except for extrinsic rewards, and the relationships were not as strong. Extraverts were found to be less satisfied than introverts with their present clerical job in terms of the work itself, supervision and co‐workers as measured by the Job Descriptive Index. Neuroticism was unrelated to job satisfaction.

Information processing and cardiovascular control.

ABSTRACTIt has previously been reported that an increase in mental task load is accompanied by a decrease in heart rate variability (HRV). In most of the experiments relating mental task load to HRV, the number of signals in paced choice reaction time tasks served as the main loading factor. However, this determinant of task load confounds muscular and mental load.In the present article we scored HRV by computing the power spectrum of the cardiac interval signal. The spectrum contains power related to respiratory activity (usually between 0.20 and 0.40 Hz) and power related to non‐linear processes involved in the control of body temperature and blood pressure (between 0.02 and 0.20 Hz). During performance on cognitive tasks the total power is attenuated, but the spectral power between 0.02 and 0.20 Hz (comprising about 80% of the total spectral energy, i.e. HRV) is particularly affected. Within this latter region we especially investigated the power between 0.06 and 0.14 Hz. The power in this region is believed to originate from processes involved in the dynamic control of mean arterial pressure. In Experiment 1 it was shown that this blood pressure‐related spectral component was rather insensitive to considerable changes in respiratory rate and depth. In Experiments 2 and 3 we kept signal rate constant but varied the cognitive demands of a sentence comprehension task and a working memory task. These experiments indicated that the power of the 0.10 Hz vasomotor oscillations was significantly affected by the processing demands of these tasks. The evidence suggested a decreased baroreflex sensitivity (i.e. a decrease in gain) during mental loading. A method was proposed to non‐invasively determine baroreflex sensitivity.

The Incentive Value of Stimuli and the Component of Cerebral Evoked Potentials

This chapter discusses the incentive value of stimuli and the component of cerebral evoked potentials. has been studied extensively in a wide variety of different paradigms in man. Most of these experiments introduced either motor or cognitive task demands and led to various interpretations concerning the psychophysiological significance of and its position in the chain of information processing stages in human central nervous system (CNS). It has been attributed to uncertainty resolution, orienting response, task relevance, probabilistic features in stimulus sequences, and to decision making. It turned out that any rare and/or task-relevant event is apt to elicit , provided that the subject is attending to the stimuli and motivated to fulfill the task demands. In contrast, only few studies investigated elicited by stimuli bearing intrinsic relevance, independent of externally established task demands. Eight schoolboys (aged 11-12 years) served as subjects (Ss). They are seated in an electrically shielded and sound-attenuated chamber and are instructed to fixate gaze on a dim green fixation point on a projection screen 1.5 m in front of them.

Striving for Response Accuracy: Experiments in New Interviewing Techniques

A dual program analyzed response invalidity and experimented with interviewing techniques designed to improve reporting. Respondent perceptions, interviewer behavior, and the relation of invalidity to characteristics of requested information are discussed and hypotheses are posed about cognitive and emotional demands of the question-answering task. In controlled experiments it was found that new interviewing techniques (instructions, feedback, and commitment) can clarify the respondent's task, enhance motivation, and thus improve reporting quality.

Children's Difficulty with Word-Referent Differentiation

MARKMAN, ELLEN M. Children's Difficulty with Word-Referent Differentiation. CHILD DEVELOPMENT, 1976, 47, 742-749. An analysis of the cognitive demands of nominal realism tasks yielded 3 related hypotheses concerning children's poor performance: (a) children fail to clearly differentiate linguistic from empirical properties, with (b) the empirical properties being more salient due in part to (c) the intangibility of words. It was found in Study I that kindergarten and first-grade children perform better on analogous tasks involving pictorial representation where the symbol is as tangible as its referent, thus supporting (c). In Study II, hypothesis a was tested by differentiating linguistic and nonlinguistic properties for the firstand second-grade subjects and hypothesis b was tested by determining whether children were as likely to attribute properties of words to their referents. The data from the first graders were fully consistent, but the data from the second graders were only partially consistent with the hypotheses. The unexpected findings could be explained by postulating 2 advances in metalinguistic development in second graders. Though speculative, this explanation was shown to be in accord with previous research and with supplementary data analyses.