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PubMed1996

The effects of task type and task requirements on the dissociation of skin conductance responses and secondary task probe reaction time.

Although task-irrelevant events elicit smaller skin conductance responses (SCRs) than do task-relevant events, secondary task probe reaction time (RT) is often slower during the former. Three experiments (N = 48 in each) examined the effects of task demands, instructions, and stimulus discriminability on this dissociation effect. SCRs were larger to task-relevant stimuli in all experiments regardless of experimental manipulation. Subjects in Experiment 1 counted either all tones of one pitch (high/low group) or longer-than-usual tones of one pitch (longer group). There was more RT slowing during task-irrelevant tones at a 250-ms probe position in the high/low group and at a 150-ms probe position in the longer group. Experiment 2 employed differential Pavlovian conditioning in which the offset of task-relevant stimuli (CS+) coincided with the onset of a shock stimulus. Half the subjects were told which stimulus would be followed by shock (information group), whereas the others received no information (no-information group). Increased RT slowing during CS- was restricted to the no-information group. Experiment 3 employed visual conditioned stimuli that were easy or difficult to discriminate. RT slowing at 4,000 ms was greater during CS+, whereas there was a tendency for more RT slowing during CS- at 150 ms. There was no effect for CS discriminability. The results suggest that during both simple discrimination and during Pavlovian conditioning, task-irrelevant stimuli are more actively processed than task-relevant stimuli within the first 250 ms of stimulus presentation.

Adolescent↗

PubMed1993

Chronic demands and responsivity to challenge.

Certain kinds of arousal in response to challenge situations reflect conditioning that makes one adaptive to task demands. A growing literature implicates chronic stress as a factor degenerating this conditioning. This study investigated the relation between objective occupational demands to which workers were classified for at least 2 years and various indicators of adaptive responsivity to challenge situations. There were consistently significant and negative relations between the occupational exposures and cardiovascular and skin temperature responsivity to the acute challenges administered in the laboratory, the corresponding speed of recovery to baseline after removal of the challenge stimulus, and peripheral catecholamine changes during a work shift.

Adaptation, Physiological↗

PubMed1979

Are retarded children more distractible? Observational analysis of retarded and nonretarded children's classroom behavior.

Retarded children are frequently characterized as more distractible and/or more outerdirected than are nonretarded children. In this study behavior thought to reflect these processes was described and the relationship of this kind of behavior to task demands was examined. Retarded and nonretarded children were observed while they worked on academic classroom tasks; retarded children were also observed while they worked on nonacademic tasks. Results indicated that retarded children were less attentive than were nonretarded children during academic periods: They spent less time on task, more time out of their seats, and more time "looking busy" but not working. Little support was found for the notion that retarded children are more outerdirected than are nonretarded children. Retarded children responded differently in nonacademic and academic situations, suggesting that behavior reflecting attention is task-related. Results were discussed in terms of previous conceptualizations of retarded persons' attention processes. Implications for future research and for educational practice were also discussed.

Attention↗

PubMed1985

Perception of emotional intonation by brain-damaged adults: the influence of task processing levels.

This research examined perception of moods from the tone-of-voice of semantically neutral phrases following unilateral cerebrovascular accident. It was hypothesized that right hemisphere damage (RHD) would impair even low-level discrimination and recognition of affective prosody, while left hemisphere damage (LHD) would affect performance only as associational-cognitive task demands increased. Thirty-three male subjects, 11 each in RHD, LHD, and normal groups, were given three tasks that varied in presumed amounts of processing undertaken for successful completion. Discrimination of prosodic patterns was expected to require the fewest cognitive operations. An intermediate task involved selecting from two possibilities the label that described moods conveyed prosodically. In the third task, prosodic mood selection was made from four choices, increasing the number of comparisons necessary for accurate judgment. As hypothesized, RHD subjects were inferior to normal subjects in all tasks. LHD subjects were equivalent to normal subjects for the first two tasks, but fell to the level of the RHD group for the third task. These results indicated that the right hemisphere in men was primarily involved in the reception and recognition of emotional prosodic stimuli. Increasing cognitive demands, however, brought about a shift in emphasis from the right hemisphere to both hemispheres. An implication of these findings concerns the need to examine performance levels that invoke changes from expected patterns of hemispheric specialization to advance our knowledge of functional asymmetries.

Adult↗

PubMed1992

Reasoning with conditionals containing negated constituents.

Three experiments investigated matching bias in conditional reasoning tasks. Matching bias occurs when Ss ignore negations and match named items. Experiment 1 used an abstract and a thematic version of Evans's (1972) construction task. Results showed that matching may be due to an interaction between task demands and constructing contrast classes when interpreting negations. Experiment 2, which used Wason's (1968) selection task, introduced a manipulation to ease contrast-class construction. Confirmation plus falsification dominated over matching. Experiment 3 introduced two other manipulations to aid contrast-class construction with abstract material. Confirmation was facilitated, matching was suppressed, and falsification remained unchanged. These results suggest that matching occurs only when insufficient or ambiguous information prevents the intended interpretation of negations.

Adult↗

PubMed1981

Age-related differences in behavior across the life span of the C57BL/6J mouse.

C57Bl/6J mice, representing four divergent age groups (ranging from 3 months to 31 months) were each tested on a number of behavioral procedures, selected to sample a wide spectrum of behaviors. The evaluation demonstrated that, as with other mammalian species, not all behaviors in the mouse are affected by old age. Most severely impaired was retention of a single-trial passive avoidance task, most probably reflecting a deficit in memory ability. One tests of motor function, the most demanding tasks revealed the greatest debilitating effects of age, paralleling the effects of task difficulty previously reported in numerous learning studies. Finally, a deficit in the ability to modify preexisting habits in a T-maze learning situation was observed, corroborating reports of increased perseveration in aged humans and nonhuman primates. The similarity of these results across the life span of the C57 mouse with those previously reported for other aged mammalian species demonstrates that certain common types of behaviors seem to be impaired selectively by increased age across mammalian species and raises the possibility that common neurological etiologies may exist for these behavioral deficits.

Aging↗

PubMed1990

Interaction of attentional and motor control processes in handwriting.

The interaction between attentional capacity, motor control processes, and strategic adaptations to changing task demands was investigated in handwriting, a continuous (rather than discrete) skilled performance. Twenty-four subjects completed 12 two-minute handwriting samples under instructions stressing speeded handwriting, normal handwriting, or highly legible handwriting. For half of the writing samples, a concurrent auditory monitoring task was imposed. Subjects copied either familiar (English) or unfamiliar (Latin) passages. Writing speed, legibility ratings, errors in writing and in the secondary auditory task, and a derived measure of the average number of characters held in short-term memory during each sample ("planning unit size") were the dependent variables. The results indicated that the ability to adapt to instructions stressing speed or legibility was substantially constrained by the concurrent listening task and by text familiarity. Interactions between instructions, task concurrence, and text familiarity in the legibility ratings, combined with further analyses of planning unit size, indicated that information throughput from temporary storage mechanisms to motor processes mediated the loss of flexibility effect. Overall, the results suggest that strategic adaptations of a skilled performance to changing task circumstances are sensitive to concurrent attentional demands and that departures from "normal" or "modal" performance require attention.

Attention↗

PubMed1986

Electrophysiology of skilled performances in children.

Skilled performance is a result of appropriate integration of sensorimotor, cognitive and motivational functions. When Piaget was asked about the nature of reality and our knowledge of it, he answered: "I know an object only when I can act on it; before this action I cannot say anything about it". It has been proposed that motor actions are the source from which mental operations emerge. The intellectual growth of a child goes through stages during which actions, perceptions and ability for concrete or abstract thought hold in turn a predominant role. On the grounds of this theoretical framework it could be argued that neuropsychophysiological investigations of skilled performance in children which incorporate the study of performance-related brain electrical activity could contribute unique information with theoretical and clinical implications. A pattern of slow and phasic brain electrical activity is consistently associated with the execution of skilled ballistic tasks. The slow potentials of the preparatory period (Bereitschfts Potential-BP) are of low amplitude in low demand tasks and in young children. The potentials closely associated with the execution of the act and reflecting sensory feedback activity (Motor Cortex Potential-MCP) are constantly present in children of all ages. The potential associated with knowledge of results (Skilled Performance Positivity-SPP) is only present if task relevant exteroceptive information is expected and occurs. The SPP is independent of the action itself and of the existence of non-informative exteroceptive stimulation. The SPP is absent in unskilled tasks and in young children. The motor performance related with the execution of the motor act improves with increasing age.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗

PubMed1996

Effects of a single cognitive task on power spectra of R-R interval and arterial blood pressure.

The present study was designed to examine the effects of a single cognitively demanding task on the R-R interval and systolic blood pressure (BP) power spectra. Ten healthy volunteers were asked to perform an English transcription task for 90 minutes using a word processor, and to read books as a non-task control. The influences of both posture and respiration were controlled in assessing the task effects. Performance of the single cognitive task significantly increased the normalized low-frequency component (% LF) of the BP spectrum following the task, as compared to the non-task control in the sitting position. However, the supine position did not produce the post-task increase in % LF of the BP spectrum. The spectral components of the R-R interval spectrum remained unchanged after the task. These results suggest that the post-task increase in sympathetic activity may be reflected by the BP spectrum under sympathetic predominance in the sitting position.

Adult↗

PubMed1991

The influence of children's facial maturity on parental expectations and punishments.

It was hypothesized that the perception of maturefaced children as more able to follow complicated instructions, more likely to know right from wrong, more shrewd, and physically stronger than their babyfaced peers would lead parents to assign more demanding tasks to these children and to judge their misbehavior more harshly. Study 1 revealed that parents allocated more cognitively demanding, but not more physically demanding, chores to maturefaced 11 year old depicted in photographs than to babyfaced children of the same age and attractiveness. Study 2 revealed that parents perceived the misbehaviors of maturefaced 4- and 11-year-old children as more intentional than those of their babyfaced peers, an effect that was significant only when parents judged children of the opposite sex. Study 2 further revealed that, with perceived intentionality held constant, a babyface mitigated the severity of punishment recommended for relatively serious infractions by preschoolers, while increasing it for older children. The latter finding was discussed in light of other evidence that people react negatively to the disconfirmation of their benign expectations regarding babyfaced individuals, and that parents perceived the misbehaviors as more unexpected for 11 year olds than 4 year olds.

Achievement↗

PubMed1981

Aging, divided attention, and processing capacity.

The performance of young and old adults was compared in two different situations to investigate the reasons why the latter are especially poor at divided attention tasks. Although the two experimental tasks were quite different, one a single task and the other time-sharing, task difficulty was manipulated in a similar fashion in both situations. Specifically, in both tasks difficulty was varied by manipulation of number of items to be rehearsed and number of mental operations necessary for successful performance. The most salient difference in task demands, that is, divided versus nondivided attention, had little effect on results. Performance of both age groups declined as task difficulty increased, with the decline being greater and more rapid for the older subjects. Results are discussed in terms of competition for limited processing capacity in working memory.

Adolescent↗

PubMedDate not supplied

Behavioral response demands, cardiovascular reactivity, and essential hypertension.

Psychophysiologic reactions to behavioral challenges were examined in men aged 55 or less with no prior history of cardiovascular disorder. Three age-matched groups of twelve were recruited through factory screening: mild hypertensives (blood pressure in the range 175/105-145/90 persisting on retest), transient hypertensives (blood pressure above criterion on screening, falling on retest), and normotensives. Clinical examination, a laboratory rest session and period of blood pressure self-monitoring were followed by a laboratory stress session. The latter involved performance of two tasks demanding active behavioral coping (the Stroop interference task and video game) and one passive condition (a distressing movie). Mild hypertensives showed significantly greater pressor reactions (both in absolute and percentage terms) than normotensives to tasks requiring active behavioral coping, but not to the passive condition. The transient hypertension group produced heightened reactions in diastolic but not systolic pressure. Greater heart rate and pulse transit time reactions were also observed in the transient group, suggesting that exaggerated cardiac responsiveness to active challenges may be characteristic of the prehypertensive profile. No differences were recorded in electrodermal or respiratory variables, or in self-reported tension. Exaggerated pressor responses were also associated with high scores on the Hostility and Direction of Hostility questionnaire, and an absence of coronary-prone behavior. Implications for the etiology of essential hypertension are considered.

Anger↗

PubMed1975

Diurnal variation in logical reasoning.

Subjects performed two tests of logical reasoning at each of six different times of day. In terms of speed, preformance on both tests was found to improve markedly from 08.00 to 14.00 and then to fall off fairly rapidly. Accuracy was found to decrease fairly linearly over the day. The results are interpreted as indicating that the different functions relating performance efficiency to time of day found by previous workers are due to differences in task demands rather than to individual differences. It is suggested that the larger the short-term memory component of a task the earlier in the day performance peaks.

Achievement↗

PubMed1993

Incidental and intentional recall in Parkinson's disease: an account based on diminished attentional resources.

The recall of common objects and their spatial location was examined in 65 patients with Parkinson's disease (PD) under conditions in which available attentional resources were manipulated by secondary task demands. PD patients were impaired at item recall particularly under intentional learning conditions but were unimpaired at recall of spatial location. These findings were similar in newly diagnosed, untreated cases as well as patients who had suffered with the disease for an average of 9.6 years. Test performance was not improved by levodopa therapy, despite it benefiting motor control, and was not impaired by anticholinergic medication. Item recall correlated significantly with other memory measures (particularly tasks of working memory) but only weakly with indices of physical disability and traditional frontal-lobe measures. Spatial recall, by contrast, correlated with memory quotient but no other cognitive measure and depression and disease duration failed to correlate significantly with performance on either recall task. These results are attributed to a deficit in attentional resources in PD that impairs performance most markedly for tasks and conditions that make the greatest demands upon effort.

Adult↗

PubMed1985

Alcohol, selective attention and sexual arousal in men.

Thirty-two men social drinkers were randomly assigned to the cells of a balanced placebo design to investigate the effects of expected and actual alcohol consumption on sexual responsiveness. Using a dichotic listening task, erotic and nonerotic information was presented in the nonattended channel while subjects performed simple (low-attention demand) and complex (high-attention demand) numerical tasks presented in the attended channel. Penile tumescence was recorded continuously in response to all audiotaped information. The high-attention demand task significantly interfered with sexual arousal compared with the low-attention demand task, primarily because of the significant suppressant effect of alcohol on arousal during the complex task. The lack of differences in tumescence under the two cognitive tasks when subjects were sober is inconsistent with the cognitive interference model of sexual arousal. Alcohol expectations increased arousal during the low-attention demand task, whereas actual alcohol consumption decreased arousal only during the high-attention demand task. Both effects are attributed to the different effects of these separate variables on attentional processes. The clinical implications are discussed.

Adolescent↗

PubMed1996

Classification deficits in Alzheimer's disease with special reference to living and nonliving things.

The present study was conducted to assess the hypothesis that visual similarity between exemplars within a semantic category may affect differentially the recognition process of living and nonliving things, according to task demands, in patients with semantic memory disorders. Thirty-nine Alzheimer's patients and 39 normal elderly subjects were presented with a task in which they had to classify pictures and words, depicting either living or nonliving things, at two levels of classification: subordinate (e.g., mammals versus birds or tools versus vehicles) and attribute (e.g., wild versus domestic animals or fast versus slow vehicles). Contrary to previous results (Montañes, Goldblum, & Boller, 1995) in a naming task, but as expected, living things were better classified than nonliving ones by both controls and patients. As expected, classifications at the subordinate level also gave rise to better performance than classifications at the attribute level. Although (and somewhat unexpectedly) no advantage of picture over word classification emerged, some effects consistent with the hypothesis that visual similarity affects picture classification emerged, in particular within a subgroup of patients with predominant verbal deficits and the most severe semantic memory disorders. This subgroup obtained a better score on classification of pictures than of words depicting living items (that share many visual features) when classification is at the subordinate level (for which visual similarity is a reliable clue to classification), but met with major difficulties when classifying those pictures at the attribute level (for which shared visual features are not reliable clues to classification). These results emphasize the fact that some "normal" effects specific to items in living and nonliving categories have to be considered among the factors causing selective category-specific deficits in patients, as well as their relevance in achieving tasks which require either differentiation between competing exemplars in the same semantic category (naming) or detection of resemblance between those exemplars (categorization).

Aged↗

PubMed1994

Comments on neuropsychological evaluation of epilepsy surgery: are the tests sensitive enough?

Epileptic lesions often affect two of the most important functions in human behavior, memory and emotion. While cognitive functions, e.g, speech and memory, are normally carefully studied, emotional and psychosocial aspects of behavior are often overlooked in the pre- and postoperative evaluation of epilepsy patients. In my comment, I will address the need for methodological and theoretical refinement, especially regarding measurements of emotional and psychosocial aspects. In evaluating memory functions, a functionalistic approach is suggested; that is, in contrast to the entity view, studies should focus on the interaction between task demands and the available cognitive capabilities of the rememberer. We should develop a broad set of tests and demonstrate dissociations between different tasks that tap different capabilities and different memory systems: we should look for patterns of results rather than single scores.

Brain↗

PubMedDate not supplied

A comparative study of the effects of carbon monoxide and methylene chloride on human performance.

The purpose of this investigation was to determine whether similar carboxyhemoglobin (COHb) values obtained from inhaling carbon monoxide or methylene chloride have the same behavioral effects. The effects were assessed by the performance of 12 humans on a visual-manual, dual-task, and an auditory vigilance task. The results indicated that both substances in concentrations sufficient to produce 5-percent COHb significantly impaired human performance under difficult or demanding task conditions. The conclusion was that carbon monoxide, the main metabolite of methylene chloride, was responsible for the observed performance decrements.

Adolescent↗