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PubMed1986

Role of task factors in visual field asymmetries.

Any tachistoscopic study of cerebral hemisphere asymmetry imposes a variety of task demands on the participants, ranging from demands imposed by specific viewing conditions to demands imposed by response output requirements. The present article discusses the role of several task factors that influence processing after the initial reception of the stimulus input, suggests a theoretical rationale for some of the effects of these task factors, and considers implications for future studies of visual laterality. The task factors discussed include both those that are relevant for minimizing artifacts that have nothing to do with hemispheric asymmetry and those that are relevant for interpreting hemispheric asymmetry in terms of specific perceptual and cognitive processes.

Attention↗

PubMed1989

Effects of age and a divided attention task presented during encoding and retrieval on memory.

The present studies were designed to examine age differences in memory when attention was divided during encoding, retrieval, or at both times. In Experiment 1, Ss studied categorized words while performing a number-monitoring task during encoding, retrieval, or at both times. Older Ss' free recall and clustering performance declined more than that of young Ss when attention was divided at encoding, but there was no similar age interaction when divided attention occurred at retrieval. In Experiment 2, the task demands at retrieval were increased by using a fast-paced, cued-recall task. The results remained unchanged from Experiment 1. Again, an age interaction occurred with divided attention at encoding but not at retrieval. These results were unexpected, given the emphasis in the memory-aging literature on increased difficulty of retrieval by older adults. The findings pose difficulties for limited processing resource views of age differences in memory.

Adult↗

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↗

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↗

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↗

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↗

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↗

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↗

PubMed1992

Development of physical fitness standards for Canadian Armed Forces younger personnel.

The purpose of this study was to develop minimum physical fitness standards based on common task criteria for personnel younger than 35 years of age in the Canadian Armed Forces. A random sample of 66 men and 144 women performed the Exercise Prescription (EXPRES) test and five physically demanding tasks that simulated common military tasks. Common cutting scores were selected as the point at which 75% of the total weighted sample passed each task. Since there were significant differences between the sexes in task performance and technique execution, the groups were analyzed separately. Results indicated a range in variance of 14 to 48% between military task performance and physical fitness test score, thus suggesting that fitness measures are a poor predictor of task performance. Because of the low variance observed the passing group of each task was treated as a representative sample of subjects whose fitness profiles were indicative of those able to meet task criteria. The 5th percentile fitness scores of the passing group were proposed as the minimum fitness standard. These conditions resulted in fitness standards that were physically more demanding for women than for men.

Adult↗

PubMedDate not supplied

[Experimental model of heuristic decision making in experiments on rats for pharmacologic screening].

In experiments on 399 rats the authors developed a method permitting the evaluation of the rate and probability of solving the task demanding from the experimental animals to survive after immersion in cold water. Each animal was exposed to stress only once in life. The task was solved by the animals with the probability rate of approximately 80-100% within 2 min. The pharmacological agents with the depriming effects (morphine, aminazine, sodium oxybutyrate, phenazepam) decreased the aim-oriented behavioral reactions of experimental animals. Caffeine (5-10 mg/kg) decreased the reaction time necessary for solving the task and phenazepam (5 mg/kg) blocked the decision made by the exposed rats to eliminate the stress situation. Nootropil and strychnine exerted no effects on the probability and quickness of the exposed rats to solve the stressful task.

Animals↗

PubMedDate not supplied

Event-related potentials in alcoholics and their first-degree relatives.

Preliminary results are presented for auditory ERPs recorded from members of alcoholic families during performance of a counting task and a choice reaction task. Alcoholic families included three adult male siblings (alcoholic proband, a second affected sib, and an unaffected sib) and parents. Control families included two adult male sibs and parents. In all experimental conditions, the N100 component was decreased in amplitude for all sibs (affected and unaffected) of the alcoholic families. The latency of the P300 component was increased for both affected and unaffected sibs compared to controls in the counting task, indicating a familial difference irrespective of drinking status. In the choice reaction task, longer P300 latencies were observed among the probands and their affected sibs as compared to their unaffected sibs, suggesting that in this more demanding task, increased latency was associated with a significant drinking history. ERP findings for children of the alcoholic probands are also discussed. The effects of differences in task complexity, drinking variables, and criteria for family selection are considered.

Adult↗

PubMed1987

Effects of gradual increases in sentence length and complexity on children's dysfluency.

To systematically evaluate the task demands of changes in utterance length and complexity, 8 normal and 8 stuttering children, ages 3:11-6:4, were administered an elicited imitation task in which the variables of syntactic complexity (as determined by normative age of acquisition) and length were manipulated to appraise their effects upon fluency and accuracy of sentence reproduction. Our findings suggest that fluency breakdown is significantly well correlated with gradual increases in syntactic complexity for both stuttering and normal children, as is sentence replication ability. Length does not appear to be as strong a predictor of fluency characteristics of elicited output. Additionally, we were unable to support a growing clinical impression of subtle language differences between normal and stuttering children; our stuttering subjects did not differ significantly from the normal children in their ability to accurately reproduce a variety of sentence types. The data suggest ways in which task complexity in stuttering therapy for young children might be ordered.

Child↗

PubMed1990

Manual asymmetries during verbal and spatial block design construction.

To examine the effects of cognitive task demands on manual asymmetry, 40 male and 40 female college students were asked to simultaneously construct two replicas of a verbal or spatial block design task, one with each hand. In addition, a verbal and spatial competition task also was performed concurrently with each of the two primary tasks in a dual task paradigm. The spatial primary task elicited increased left-hand use relative to baseline performance, but only in males. An increase in right-hand use was observed during performance of the verbal primary task, again primarily among males. The effects of concurrent cognitive tasks on hand utilization were observed only in subjects performing the verbal primary task, and only when the concurrent task was verbal in nature. Implications for theories of functional cerebral lateralization are discussed.

Adult↗

PubMedDate not supplied

Historical factors in the development of ETOH-conditioned place preference.

Three groups of male Sprague-Dawley rats were conditioned with ethanol (ETOH) and water in a Conditioned Place Preference task. To assess the contribution of prior drug/behavioral history on the relative hedonic valence of ETOH, the three groups differed in the task demands and degree of prior ETOH exposure. One group was trained to self-administer 20% w/v ETOH in a home-cage self-administration task using a "Samson sucrose-fading" procedure prior to place conditioning trials (Group SA/CPP). A second group was initially trained in a two-choice ETOH-Saline drug discrimination (DD) task and subsequently conditioned in the place preference paradigm (Group DD/CPP). The third group of rats had no history of drug exposure and were experimentally naive prior to the place learning task (Group NH/CPP). Group SA/CPP developed a significant conditioned place preference; Group DD/CPP failed to demonstrate either a preference or aversion, whereas the Group NH/CPP demonstrated a significant place aversion. Data suggest that both present and past contingencies contribute to the algebraic summation of ETOH's hedonic valences.

Animals↗

PubMed1992

Cigarette smoking and cognitive performance.

While some investigations into the relationship between smoking and cognitive performance have reported that smoking facilitates performance, other research has come to the opposite conclusion. A review of the literature suggests that this variance in results may be due to differences among studies in design (comparing smokers only with deprived smokers rather than with non-smokers) and also to differences in task demands. Therefore, performance of smokers having just smoked, matched smokers deprived for a brief period, and also non-smokers was contrasted on a series of tasks which ranged from repetitive and perceptually-bound tasks to complex, dynamic tasks dependent upon long-term memory. It was found that while cigarette smoking had no negative effect upon performance for simple perceptual tasks, smoking was found to exert measurable negative effects upon performance for more complex information processing tasks.

Adult↗