Acute and chronic stress effects on performance in a forced-swim task

The effects of uncontrollable stressors on performance in a subsequent forced-swim paradigm were assessed in mice. Uncontrollable shock initially induced behavioral invigoration; however, within 24 h of stressor application, swimming behavior was depressed relative to nonstressed mice. The controllability of the stressor did not influence the initial invigoration, being present among escapably shocked mice as well as among mice that received (yoked) inescapable shock. In contrast, the depression of responding evident 24 h after stressor application was related to the availability of behavioral coping methods. Finally, following repeated exposure to footshock there was no indication of adaptation to the behavioral changes ordinarily induced by acute shock stress. The data were related to the effects of uncontrollable stressors on escape performance, and with respect to the use of this preparation as an animal model of human depression.     

The effects of mental representation on performance in a navigation task

In three experiments, we investigated the mental representations employed when instructions were followed that involved navigation in a space displayed as a grid on a computer screen. Performance was affected much more by the number of instructional units than by the number of words per unit. Performance in a three-dimensional space was independent of the number of dimensions along which participants navigated. However, memory for and accuracy in following the instructions were reduced when the task required mentally representing a three-dimensional space, as compared with representing a two-dimensional space, although the words used in the instructions were identical in the two cases. These results demonstrate the interdependence of verbal and spatial memory representations, because individuals' immediate memory for verbal navigation instructions is affected by their mental representation of the space referred to by the instructions.     

The effects of music and task difficulty on performance at a visual vigilance task

Forty subjects performed a visual vigilance task in music or noise and when the task was difficult or easy. Response measures taken were: correct detections, commission errors, detection latencies and d' values. For the difficult version of the task a significant increase in detection latencies was found which music prevented. Broadly similar findings were obtained for correct detections. The results are compared with other studies of detection latency and task difficulty and are discussed in terms of arousal.     

The effects of dialogue-based task allocation on system performance in a computer-aided air traffic control task

The present study investigated dialogue-based human-computer task allocation. Five levels of allocation mode, four command strategies and a control condition, were examined in a high-task-load situation using a Latin square design. Five male participants acted as controllers in a simplified representation of an air traffic control system, sharing their task with a computer controller. Performance measures were metered on-line, and subjective ratings were recorded between trials. There were significant differences among the groups in the percentage of planes landed by the human-computer system, the total number of commands executed, and the number of allocation commands used. Other variables suggested for further study include comparisons of input mode, dialogue-initiation style, and degraded performance levels of the computer controller.     

Social influence and sex effects on task performance and task perceptions

A laboratory experiment was conducted to investigate the effects of observer presence and subject sex on both performance quantity and quality, job satisfaction, and task perceptions. Multivariate analysis of covariance (MANCOVA) results demonstrated statistically significant multivariate effects on the performance measures. Significant main effects of observer presence were found for performance quality but not quantity. A significant observer presence x subject sex interaction was found for performance quantity. The results for task perceptions supported the hypothesis that the situational factors would make salient the significance of the task. Main effects of observer presence were found for task significance only. Also there was a significant observer presence x subject sex interaction on perceptions of task significance. No effects were found on job satisfaction, consistent with past research. The results are discussed relative to social facilitation research in the broader context of social influence.     

The effects of age and task context on Stroop task performance

In this study, we investigated the impact of age and task context on Stroop task performance, using error scores, response latencies, and process dissociation estimates (e.g., Lindsay & Jacoby, 1994). Across three experiments, the findings showed that although older adults were able to evaluate Stroop task demands and modify their representations of task context in response to this knowledge, they were less able to maintain and update these representations on a trial-by-trial basis in tasks with high stimulus uncertainty or ambiguity. Moreover, although there was no age-related decline in the ability to modulate print color information, older adults were consistently less able to control the activation of conflicting word information. Together, these findings suggest that whereas age differences in the Stroop task may be magnified under conditions that promote transient failures to maintain task context, the primary source of these differences seems to be a more enduring decline in the efficiency of processes that are responsible for suppressing the activation of irrelevant lexical information.     

The effects of workload history on dual task performance

The purpose of this study was to examine the effects of workload history (specifically sudden workload shifts) on performance. A sample of 204 undergraduates was randomly assigned to either a sudden decrease or increase in workload condition. Participants simultaneously performed a memory search task (i.e., primary task) and an auditory vigilance task (i.e., distracter task), while percent correct was recorded. Separate Repeated Measures ANOVA’s revealed a significant treatment effect for the Medium to Low (F(l, 110) = 274.6, p < .01) and Low to Medium (F(l,92) = 148.3, p < .01) conditions. Results supported previous research suggesting that either a sudden decrease (Medium to Low) or increase (Low to Medium) in workload could be detrimental to performance (Cox-Fuenzalida, 2000). More importantly, this study extends the detrimental effects of workload history to a dual task environment. The authors express their gratitude to the research team from the Personality and Human Performance Lab at the University of Oklahoma for their invaluable assistance in data planning and collection.     

The effects of workload history on dual task performance

The purpose of this study was to examine the effects of workload history (specifically sudden workload shifts) on performance. A sample of 204 undergraduates was randomly assigned to either a sudden decrease or increase in workload condition. Participants simultaneously performed a memory search task (i.e., primary task) and an auditory vigilance task (i.e., distracter task), while percent correct was recorded. Separate Repeated Measures ANOVA’s revealed a significant treatment effect for the Medium to Low (F(l, 110) = 274.6, p < .01) and Low to Medium (F(l,92) = 148.3, p < .01) conditions. Results supported previous research suggesting that either a sudden decrease (Medium to Low) or increase (Low to Medium) in workload could be detrimental to performance (Cox-Fuenzalida, 2000). More importantly, this study extends the detrimental effects of workload history to a dual task environment. The authors express their gratitude to the research team from the Personality and Human Performance Lab at the University of Oklahoma for their invaluable assistance in data planning and collection.     

The effects of phenytoin on the performance of rats in a delayed match-to-place task

We have shown previously that phenytoin impairs learning in rats in several different behavioral paradigms (Churchill et al., 1998, 2003; Banks et al., 1999). The present study has examined this drug’s effects on performance in a delayed match-to-place water maze paradigm developed by Steele and Morris (1999). We find that phenytoin retards performance, but only when the inter-trial interval (ITI) is short (i.e., 15-sec). With longer ITIs (i.e., 20-min, 2-hr), the performance of the phenytoin-treated rats was quite comparable to the controls. We suggest that this pattern of results stems from a disruption of spatial working memory, perhaps due to the effects of the drug on hippocampal function (cf., Churchill et al., 1998, 2003). This disruption is, however, not so profound that consolidation is prevented.     

The effects of aging on remembering intentions: performance on a simulated shopping task

Three studies are described in which age differences on a task measuring memory for delayed intentions using naturalistic stimuli were examined. A simulated street scene was constructed from a network of photographs and sounds that participants could move through using a touch screen while completing a series of event‐based shopping errand instructions. The objective of the research was to identify the cognitive processes involved in the task that were vulnerable to the effects of ageing. Memory search but not cue detection was specifically affected in older persons when participants were given fewer trials to learn the instructions. There was no age specific effect on cue detection or memory search in either an unfamiliar street or one with increased levels of irrelevant visual and auditory noise. Cue detection but not memory search was disproportionately affected in older persons after filled interruptions, suggesting that the capacity for self‐initiated reinstatement of working memory is reduced in old age. In general, using a computer‐based simulation of a real‐life task was found to be a practical means of examining the effects on behaviour and cognition of task parameters that are significant in assessing everyday memory abilities. Copyright © 2006 John Wiley & Sons, Ltd.     

The effects of age and task domain on dual task performance: A meta-analysis

Recent research has provided mixed findings as to whether older adults find dual tasking problematic. Here, we examined whether methodological variations across studies can account for the discrepancies in the literature. Meta-analyses conducted on the results of 34 studies conducted between 1981 and 2003 found a strong overall effect size (d = .68), which indicated a clear age-related dual tasking impairment. However, this effect size was not representative of all the individual studies reported. Subsequent analyses, using an analysis of variance analogue (Hedges & Olkin, 1985), investigated potential moderators responsible for the variability in the effect sizes across studies. These secondary analyses included a comparison of dependent measure used, whether baseline differences in performance had been controlled for, and task domain. Task domain was found to be the critical moderator variable. Notably, tasks with a substantial controlled processing, or motor component showed greater dual task impairment than tasks that were relatively simple or relied on automatic processing.     

The interactive effects of task complexity and participation on task performance: A field experiment

Goal-setting investigators have suggested that participation in the goal-setting process may be important for both motivational and cognitive reasons; however, goal-setting research has focused almost exclusively on the motivational aspect of participation, while generally ignoring the cognitive aspect. In an attempt to demonstrate the cognitive implications of participation, a field experiment was conducted with 40 computer programmers writing either a simple or a complex program. Half the participants were actively involved in discussing the project and in jointly determining the completion target, while the other half were simply assigned completion times of equivalent difficulty. It was hypothesized that, for complex programs, individuals participating in the discussion process would outperform individuals having assigned targets of similar difficulty. In contrast, for simple programs, it was expected that participation would have no effect on task performance. The data were analyzed using a 2 × 2 ANOVA procedure, and results strongly supported the hypothesized interaction. Discussion centered on the implications of the findings for future research in this area.     

The effects of a target–stimulus reminder on performance in a novel object recognition task

The effects of original training-stimulus pre-test reminders were examined in a novel object recognition (NOR) task. NOR is a task that examines memory for complex stimuli, and is driven by the rats’ tendency to spend significantly more time exploring novel objects over those previously experienced. In this task, a delay is imposed between a training experience during which the animal is allowed to investigate a set of identical objects, and a later test exposure where the animal encounters one of the original objects and a novel object with which it has had no previous experience. Experiment 1 demonstrated that performance at 24 h is significantly worse than at an immediate delay (1 min). In the second experiment, it was demonstrated that neither a 10-s nor a 30-s reminder treatment, in the absence of training, resulted in a level of preference for novelty, a measure of memory for the original object, that was significantly greater than chance. Experiment 3 illustrated significant performance effects of a 30-s training stimulus reminder administered 15 min prior to test with a 24-h retention interval. The final experiment illustrated that the additional 30-s of object exposure is effective in enhancing performance only if it occurs shortly prior to test. Animals receiving the additional 30-s immediately following training did not experience such beneficial effects. It was concluded, based upon these results, that pre-test training-stimulus reminders in this task produce effects similar to those seen in more traditional tasks of learning and memory.     

Stimulus effects on cancellation task performance in children with and without dyslexia

Both the sensitivity and administration time of a test are important in evaluating visuospatial attention in clinical settings, especially with respect to external validity. The purpose of the present study was to propose an adaptive model that provides a reference for test modification by manipulating target-to-distractor (T/D) ratios and the number of stimuli on the computerized cancellation test system. Tasks with different T/D ratios and numbers of stimuli were presented to two groups—children with and without dyslexia (n=41 and 65, respectively)—to determine whether their visuospatial attention performance differed on different test forms. In general, there were significant differences between the two groups in hit rates, completion times, and performance quality (PQ) scores. The PQ score of visual attention was affected by the T/D ratios rather than by the number of stimuli. The findings suggested that the T/D ratio has a strong effect on PQ scores, and that it should be taken into consideration in test and task design.     

The effects of task instructor status on prospective memory performance in preschoolers

The present study applied a 2 × 2 experimental design to assess prospective memory (PM) development across preschool age and to examine the effect of task instructor status (researcher vs. significant other) on PM performance in 80 preschool children. Participants were required to name pictures (ongoing task [OT]), and to remember to refrain from naming but instead give a different response to certain target cues (PM task). Although the OT was of comparable difficulty for both age groups (as indicated by no performance differences), results still indicated significantly higher PM performance in 5-year-olds than in 3-year-olds, confirming the age-related increase of PM capacities between 3 and 5 years. Furthermore, results showed a performance-enhancing effect of significant others as task instructors on both age-groups. Post-hoc analysis revealed that 3-year-olds instructed by a significant other still performed marginally worse than 5-year-olds instructed by a researcher, underlining the finding that substantial changes of PM capacities take place during early childhood.     

Category discriminability, base-rate, and payoff effects in perceptual categorization

The optimality of perceptual categorization performance under manipulations of category discriminability (i.e., d' level), base rates, and payoffs was examined. Base-rate and payoff manipulations across two category discriminabilities allowed a test of the hypothesis that the steepness of the objective reward function affects performance (i.e., the flat-maxima hypothesis), as well as the hypothesis that observers combine base-rate and payoff information independently. Performance was (1) closer to optimal for the steeper objective reward function, in line with the flat-maxima hypothesis, (2) closer to optimal in base-rate conditions than in payoff conditions, and (3) in partial support of the hypothesis that base-rate and payoff knowledge is combined independently. Implications for current theories of base-rate and payoff learning are discussed.