Effects of divided attention on implicit and explicit memory performance following severe closed head injury.

This study investigated the relation between attentional limitations and memory impairments in patients with closed head injuries (CHI). Twenty-seven CHI participants ( > 1 year postinjury) and 27 matched controls rated their liking of target words under conditions of full and divided attention. Participants then completed an implicit test of tachistoscopic identification (TI) and an explicit test of recognition for the target words As expected, the results revealed impaired explicit memory but preserved perceptually driven implicit memory performance following a CHI. Contrary to what was hypothesized, a reduction in attention available at encoding did not disproportionately impair the recognition performance of the CHI patients. Finally, unlike controls, the CHI participants' priming scores on the TI task were significantly affected by dividing attention at encoding. However, this finding interacted with CHI participants perceptual processing rates, suggesting that nonmemory cognitive factors may influence measured performances on implicit memory tests. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Auditory vigilance under hypoxia.

Tested the vigilance performance of 12 young U.S. Army enlisted men on a 2-hr loudness discrimination task under 4 levels of hypoxia: 21% oxygen (sea level); 12.8% oxygen (13,000 feet); 11.8% oxygen (15,000 feet), and 10.9% oxygen (17,000 feet). Results indicate a significant decrement in signal detection as a function of severity of hypoxia and task duration. These findings parallel those of visual vigilance studies and suggest that the function affected by hypoxia is a central attention process rather than an orienting response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic process development following severe closed head injury.

Automatic process development was investigated in a closed head injury (CHI) population. Ten severe CHI participants (>1 year postinjury) and 10 matched controls completed consistent mapping (CM) and varied mapping (VM) semantic-category memory search tasks. In VM search, despite a similar pattern of serial memory search, the CHI participants responded slower than controls and exhibited slower memory search rates throughout practice (1,800 trials). In CM search, after extensive practice (1,800 trials) both groups showed the performance characteristics indicative of automatic process development, that is, near-zero slopes and large reductions in response times. However, the CHI participants were slower to automatize the task. These results indicate that for memory-based search tasks the effects of a CHI may slow down the speed with which automatic processes develop but that CHI participants can acquire and use automatic processes in task performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vigilance performance under hypoxia.

Tested vigilance performance by 20 young male military Ss on a 2-hr brightness discrimination task under 4 levels of hypoxia: 21% oxygen (sea level), 12.8% oxygen (13,000 ft.), 11.8% oxygen (15,000 ft.), and 10.9% oxygen (17,000 ft.). Results indicate a significant decrement in signal detection as a function of severity of hypoxia and task duration. Analyses of d' and BETA show a significant decrease in detectability of the signal as a function of hypoxia, but no change in caution of decision making. Individual variation in performance was related to field dependence as measured by the Embedded Figure Test (EFT). EFT score correlated negatively with false detection rate, and positively with RT and d', indicating a negative relationship between field dependence and vigilance performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intactness of inhibitory attentional mechanisms following severe closed-head injury.

Attentional problems are a common sequelae of closed-head injury (CHI). Research in the area of selective attention has pointed to the role of inhibitory mechanisms in the suppression of irrelevant information. In the current study, a negative priming paradigm was used to assess the inhibitory mechanisms of individuals suffering from a severe CHI. Twenty participants with severe CHIs (greater than 1 year postinjury) and 20 matched controls completed a negative priming task, as well as several other standardized tests of cognitive functioning. Within the negative priming task, 2 conditions were used to elicit information regarding facilitation by attended and ignored information and 1 condition was used to elicit inhibition of ignored information, as compared with a neutral control condition. Despite poorer performances on several tests of attention, there were no significant differences in the amount of inhibition displayed by the CHI participants as compared with the controls. Findings suggest that inhibitory processing deficits may not underlie the selective attention difficulties commonly seen following a severe CHI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of anticipatory alerting signals and a compatible secondary task on vigilance performance.

This visual vigilance study simulated an industrial inspection task in which Ss were alerted to possible targets by a semiautomatic detection device. 1 experimental group was forewarned of possible targets by a buzzer with 1-sec foreperiod and rested between alerting signals. A 2nd experimental group worked on a problem-solving secondary task instead of resting between buzzes. A control group observed the display continuously. Other variables of interest were sex of O, target type, and size of display window. It was found that: (1) performance by alerted groups was far superior to that of controls and continued to improve throughout the task, (2) a vigilance decrement was not in evidence in any condition, (3) the problem-solving task did not interfere with detection performance, (4) male and female Ss performed equally well, and (5) Ss engaged in the problem-solving task greatly underestimated the duration of the detection task and reported it "interesting" while the other groups estimated duration accurately and indicated boredom. (16 ref.) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Maintainance of vigilance in an auditory monitoring task.

4 levels of critical signal frequency and 3 levels of task complexity were compared for their effect on vigilance in an auditory monitoring task. Proportionate omission errors increased as the frequency of signals decreased, as expected. However, complexity (defined as the number of categories of critical signals) had an unexpected effect in that relatively poor performance occurred with increased complexity. The results were interpreted as suggesting caution in the use of artificial signals as a means to overcome loss of vigilance in monitoring tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retrieval Inhibition in Directed Forgetting Following Severe Closed-Head Injury.

A variant of the list method directed forgetting procedure was used to examine the role of inhibition in memory performance following severe closed-head injury (CHI). Twenty-four participants with severe CHI and 24 controls studied picture and word stimuli in both forget and remember conditions. Memory testing for the to-be-forgotten and to-be-remembered items consisted of a free-recall test followed by a source-monitoring task. Despite poorer recall performance, the participants with CHI exhibited a directed forgetting effect similar to that in controls. Item recognition scores indicated that the inhibited items were not forgotten but rather were items whose accessibility had been lowered. These findings suggest that residual memory deficits in patients with severe CHI are unlikely to reflect inefficient retrieval inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detecting threat-related intentional actions of others: Effects of image quality, response mode, and target cuing on vigilance.

Three experiments examined the vigilance performance of participants watching videos depicting intentional actions of an individual’s hand reaching for and grasping an object—involving transporting or using either a gun or a hairdryer—in order to detect infrequent threat-related actions. Participants indicated detection of target actions either manually or by withholding response. They also rated their subjective mental workload before and after each vigilance task. Irrespective of response mode, the detection rate of intentional threats declined over time on task and subjective workload increased, but only under visually degraded viewing conditions. This vigilance decrement was attenuated by temporal cues that were 75% valid in predicting a subsequent target action and eliminated with 100% valid cues. The findings indicate that detection of biological motion targets, and threat-related intentional actions in particular, although not attention sensitive under normal viewing conditions, is subject to vigilance decrement under degraded viewing conditions. The results are compatible with the view that the decrement in detecting threat-related intentional actions reflects increasing failure of attention allocation processes over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conceptual complexity and preferred coping strategies in anticipation of temporally predictable and unpredictable threat.

Conceptualized the coping strategies of vigilance and avoidance as information search patterns, which were viewed from an information-processing perspective. Conceptual complexity (measured here by the Paragraph Completion Test) was examined as a mediator of response to environmental stress. The major issues of interest were whether (1) the choice of a vigilant or avoidant coping strategy would be related to individual differences in conceptual complexity level, (2) differences in complexity level would be related to patterns of physiological arousal and subjective anxiety, and (3) the cognitive performance of conceptually complex and simple Ss would be differentially affected by variations in environmental threats. 120 female undergraduates served as Ss. Contrary to expectation, the results indicate that when anticipating a temporally unpredictable shock, conceptually simple Ss were more vigilant (behaviorally and cognitively) and reported more subjective anxiety than conceptually complex Ss. Results also indicate that the conceptually complex Ss exhibited higher levels of skin conductance overall than the conceptually simple Ss. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vigilance performance in a bimodal task.

Evaluated the need for an arousal construct in a theory of vigilance, as opposed to a theory based on a selective attention construct. Performance over time was examined in a situation involving 2 detection tasks, 1 in each of 2 modalities. 34 undergraduates were instructed to direct their attention to 1 of the 2 tasks, the primary task; the other task was of secondary importance. The main concern was in discovering whether the vigilance decrement would be specific to the primary task, as would be suggested by the selective attention theory, or whether it would be seen in both tasks, as suggested by the arousal construct. Data show that the decrement is task specific. However, it is not always the primary task which shows the decrement. It is argued that neither the construct of arousal nor that of selective attention is adequate, alone, to deal with the vigilance decrement. Results are discussed in terms of these 2 concepts and in terms of some practical implications for the design of real-life displays. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual selective attention after severe closed head injury

This study investigated the nature of selective attention deficits after severe closed head injury (CHI). Twenty participants with severe CHI (greater than 1 year postinjury) and 20 matched controls completed search and nonsearch visual selective attention tasks under conditions of low (Experiment 1) and high (Experiment 2) target-distractor similarity. In the search situations, participants searched visual displays that contained 1, 4, or 8 items for the targets. In the nonsearch situations, the location of the targets was visually cued with a peripheral arrow. The results revealed that in both the low and high target-distractor similarity search conditions. CHI participants required a longer time than controls to locate and identify the target. In contrast, in the nonsearch condition, CHI participants were able to successfully ignore irrelevant task information when target-distractor similarity was low. However, when target-distractor similarity was high, CHI participants had more difficulty than controls ignoring the irrelevant information. These results suggest that, in comparison to controls, CHI participants may be at a disadvantage in selective attention situations when visual search is required and when the discriminability between targets and distractors is difficult.     

Naturalistic action impairment in closed head injury.

The authors sought to determine whether errors of action committed by patients with closed head injury (CHI) would conform to predictions derived from frontal lobe theories. In Study 1, 30 CHI patients and 18 normal controls performed routine activities, such as wrapping a present, under conditions of graded complexity. CHI patients committed more errors even on the simplest condition; but, except for a higher proportion of omitted actions, their error profile was very similar to that of controls. Study 2 involved a subset of patients whose performance in Study 1 was within normal limits. When these high functioning patients were asked to perform the routine tasks under still more taxing conditions, they, too, committed errors in excess of the control group. Accounts based on frontal mechanisms have a difficult time explaining the overall pattern of findings. An alternative based on limited-capacity resources is suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive Performance and Autonomic Reactivity in Abstinent Drug Abusers and Nonusers.

In this study the authors compared the performance of abstinent drug abusers (n = 21) and nonuser control participants (n = 20) in neurocognitive and emotional functions by use of the Rogers Decision Making Task, Gambling Task, Emotional Stroop, impulsivity continuous performance task (CPT), and vigilance CPT. Skin conductance (SC) and heart rate (HR) monitoring was synchronized with task performance. Groups showed similar performance for vigilance, impulsivity, and emotional interference; however, drug abusers showed stronger SC responses. Drug abusers performed more poorly on the Gambling and Rogers Decision Making Tasks. When making risky decisions, drug abusers showed significantly less increase in SC activity than controls and exhibited lower HRs throughout performance on all tasks. In conclusion, complex tasks involving decision making, sensitivity to consequences, and emotional regulation discriminated between drug abusers and controls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sustained-attention capacity in young and older adults.

The sustained-attention capacity of young (21–29 years) and older (65–78 years) adults was examined using a high-event rate digit-discrimination vigilance task presented at 3 levels of stimulus degradation. Increased stimulus degradation led to a reduction in the hit rate and to a greater decline in hit rate over blocks (increased vigilance decrement). Sensitivity (d') declined over blocks only at the highest level of stimulus degradation. Older adults had a lower hit rate and showed greater vigilance decrement than young adults, particularly when stimuli were highly degraded. However, both age groups showed the same pattern of stability in sensitivity when stimulus degradation was moderate, and sensitivity decrement over time when stimulus degradation was high. The results suggest that the process of sustained allocation of capacity—as reflected in temporal changes in sensitivity—operates similarly in young and older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual monitoring performance in three subgroups of male delinquents.

Administered a questionnaire measuring psychopathic, neurotic, and subcultural delinquency to 268 male delinquents. 3 groups of 15 Ss each were formed from Ss who scored above the mean on 1 scale and below the mean on the other 2. It was predicted that the more psychopathic Ss would show a greater performance decrement on a vigilance task. A significant effect was found between groups and a significant decrement over trials for signals detected and RTs; psychopathic Ss performed consistently poorer than the other 2 groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences in sustained attention across the adult life span.

We used a life span sample of 18- to 91-year-old men (n?=?176) and women (n?=?108) to investigate sex differences and the effect of age on sex differences in performance and arousal during a 62-min no-memory-demand sensory vigilance task (Mackworth's Clock-Test). We observed sex differences in target response time and on measures of autonomic arousal; women were slower and less aroused than men. A review of the literature, in conjunction with the results of this study, led to our concluding that women are slower to respond to targets than men and that women may tend to detect fewer targets than men only when they are young (18–29 years old). Sex differences in arousal levels were consistent with an arousal explanation of sex differences in response time. However, detection accuracy and false alarm rates were not consistent with sex differences in arousal levels. Sex differences in the time course of vigilance performance were inconsistent. Age did not significantly moderate the sex differences in vigilance decrement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A functional magnetic resonance imaging study of auditory vigilance with low and high information processing demands.

This study identified the brain activations associated with auditory vigilance tasks, using functional magnetic resonance imaging. We created auditory continuous performance tests (CPTs) in which a demanding task (working memory task) was made more difficult than a simple vigilance task by increasing working memory and interference filtering demands. Two cohorts of normal male controls performed significantly worse on the working memory CPT than on the vigilance task. Compared to the vigilance task, performance of the working memory task produced significant signal change in lateral and medial prefrontal cortex, precentral cortex, temporal lobe, including insula and hippocampus, parietal-occipital cortex, cingulate, thalamus, and superior colliculus. Performance and degree of activation was associated with an estimate of IQ. Further research should clarify the contributions of working memory and interference filtering to the activated network. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The mediation of reward-induced motivation decrements in early and middle childhood: A template matching approach.

Under certain circumstances, children's intrinsic motivation (IM) to engage in an activity may be undermined as a consequence of being induced to engage in that activity in return for tangible rewards. The present study with 25 females and 20 males (4–10 yrs) attempted to identify the process(es) mediating this effect during early and middle childhood, by simultaneously testing 5 hypotheses that may plausibly be advanced to account for it. The possibility that different mediators may be operative at different age levels was also examined. IM was assessed before and after an offer and delivery of reward contingent on task engagement. Independently, predictions (templates) were derived from each hypothesis regarding the personality characteristics of an S predicted to exhibit the greatest reward-induced decrement IM. Individual differences in Ss' personalities were assessed on the California Child Q-Sorts, which were then matched with each template to predict motivation decrement. Among males, 2 hypothesized mediators in which the perception of personal control is central accounted for significant portions of the variance in motivation decrement. None of the hypotheses were supported among females. Some developmental changes in mediation were also found and discussed. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuropsychological effects of closed head injury in older adults: A comparison with Alzheimer's disease.

In this study, neuropsychological profiles of 14 older adult patients with mild or moderate closed head injury (CHI). 14 patients with probable Alzheimer's disease (AD), and 14 community residing elderly controls were compared. The groups were similar in demographic features, and the CHI and AD patients had comparable Mini-Mental State Examination scores. Tests of verbal learning and memory, letter and category fluency, and naming were administered. Relative to the CHI group, AD patients exhibited more devastated memory and did not show a normal facilitation on the category retrieval task. The patient groups exhibited similar levels of categorical clustering and naming accuracy for both high- and low-frequency words. These results suggest that neuropsychological markers of memory and semantic processing may be useful in differentiating the cognitive effects from AD versus early recovery from CHI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)