Sustained attention, attentional selectivity, and attentional capacity across the lifespan

Changes in sustained attention, attentional selectivity, and attentional capacity were examined in a sample of 113 participants between the ages of 12 and 75. To measure sustained attention, we employed the sustained-attention-to-response task (Robertson, Manly, Andrade, Baddeley, & Yiend, Neuropsychologia 35:747?C58, 1997), a short continuous-performance test designed to capture fluctuations in sustained attention. To measure attentional selectivity and capacity, we employed a paradigm based on the theory of visual attention (Bundesen, Psychological Review 97:523?C547, 1990), which enabled the estimation of parameters related to attentional selection, perceptual threshold, visual short-term memory capacity, and processing capacity. We found evidence of age-related decline in each of the measured variables, but the declines varied markedly in terms of magnitude and lifespan trajectory. Variables relating to attentional capacity showed declines of very large effect sizes, while variables relating to attentional selectivity and sustained attention showed declines of medium to large effect sizes, suggesting that attentional control is relatively preserved in older adults. The variables relating to sustained attention followed a U-shaped, curvilinear trend, and the variables relating to attentional selectivity and capacity showed linear decline from early adulthood, providing further support for the differentiation of attentional functions.     

Residual attentional capacity amongst young and elderly during dual and triple task walking

Walking is considered an automatic function which demands little attentional resources. Thus a residual attentional capacity is available for a concurrent task (dual task). Minor age-related deficits in postural control may minimize the residual attentional capacity, however this may not be detected by a simple examination of the individuals gait performance. This study investigated the use of challenging dual task combinations to detect age related changes in gait performance. Eleven community-dwelling elderly (mean age 76 years) and 13 young subjects (mean age 26 years) participated in the study. The participants walked along a figure-of-eight track at a self-selected speed. The effect of introducing a concurrent cognitive task and a concurrent functional motor task was evaluated. Stride-to-stride variability was measured by heel contacts and by trunk accelerometry. In response to the cognitive task the elderly increased their temporal stride-to-stride variability by 39% in the walking task and by 57% in the combined motor task. These increases were significantly larger than observed for the young. Equivalent decreases in trunk acceleration autocorrelation coefficients and gait speed were found. A combination of sufficiently challenging motor tasks and concurrent cognitive tasks can reveal signs of limited residual attentional capacity during walking amongst the elderly.     

Hypnotic susceptibility, baseline attentional functioning, and the Stroop task

According to the theoretical framework relating hypnosis to attention, baseline attentional functioning in highly hypnotizable individuals should be more efficient than in low hypnotizable individuals. However, previous studies did not find differences in Stroop-like tasks in which the measure indicative of the Stroop interference effect was based on response latencies. This study was designed to determine whether subjects with different levels of hypnotic susceptibility show differences in baseline attentional functioning. To assess this hypothesis, high, medium, and low hypnotizable subjects performed a Stroop task designed to evaluate accuracy performance, before being subjected to hypnotic induction. Results showed that the Stroop interference effect was smaller in high hypnotizable subjects than in low hypnotizable subjects, whereas it was not different between high, and medium hypnotizable subjects. This outcome supports the notion that baseline attentional functioning is related to hypnotic susceptibility.     

T1 difficulty and the attentional blink: expectancy versus backward masking

According to bottleneck models of the attentional blink (AB), first-target (T1) processing difficulty should be related to AB magnitude. Tests of this prediction that have varied T1 difficulty in the context of a standard AB paradigm, however, have yielded mixed results. The present work examines two factors that may mediate the relationship between T1 difficulty and the AB: observer expectancy and backward masking of T1. In two experiments, omission of the backward mask consistently yielded the predicted relationship between T1 difficulty and the AB. In contrast, observer expectancy influenced target identification accuracy but did not mediate the relationship between T1 difficulty and the AB.     

Effects of primary task predictability and secondary task modality on lane maintenance

The objective of this work was to investigate the effects of auditory and visuo-spatial secondary tasks on variability in lane position in predictable and unpredictable driving conditions. Sixty-six participants drove a simulated vehicle. Predictability was manipulated by adding wind gusts, and the secondary task load by either an auditory task (Experiment 1) or a visuo-spatial task (Experiment 2). Results demonstrated that in the predictable driving condition, lane position variability decreased when auditory secondary task load was given, but it was not affected by visuo-spatial secondary task load. In the unpredictable driving condition; however, while the auditory secondary task load did not affect lane position variability, visuo-spatial secondary task load increased it. The data suggests that the effects of cognitive load on lane maintenance may depend on the type of the secondary task beside predictability of primary task.     

The relationship between sustained attention,attentional selectivity,and capacity

The Theory of Visual Attention (TVA; Bundesen, 1990) provides a quantitative account of visual attentional selectivity and capacity but does not include a parameter relating to sustained attention. We conducted two studies to examine the relationship between sustained attention and the TVA parameters relating to selectivity and capacity. In the first study (n=46; mean age=41, SD=10), we investigated the effects of self alerting during a combined whole and partial report task (CombiTVA). In the second study, 70 participants (aged 20–69), performed the CombiTVA and the Sustained Attention to Response Task (Robertson, Manly, Andrade, Baddeley, & Yiend, 1997). The results indicated that attentional selectivity and capacity were unaffected by self alerting, unrelated to sustained attention ability and robust to the adverse effects of time-on-task. These findings are in keeping with the idea of independent functions relating to sustained attention and attentional selectivity and capacity.     

Monetary reward increases attentional effort in the flanker task

An important question is whether monetary reward can increase attentional effort in order to improve performance. Up to now, evidence for a positive answer is weak. Therefore, in the present study, the flanker task was used to examine this question further. Participants had to respond sooner than a certain deadline in a flanker task. One group of participants received a performance-contingent monetary reward, whereas the other group earned a fixed amount of money. As a result, monetary reward significantly improved performance in comparison with the control group. The analysis of speed-accuracy trade-off functions revealed that monetary reward increased attentional effort, leading to an enhanced quality of stimulus coding. Little evidence was found that reward also improved selective spatial attention.     

Channel capacity and processing of modality specific information

The synthesis model, designed to explain effects of modality specific information on retention, is presented and tested. The model encompasses qualitative and quantitative components. The qualitative characteristics reflect the physiological properties of the auditory and visual channels. Three parameters are assumed to affect the quantitative efficiency of the channels. Each channel is assumed to have a certain capacity, and processing of information in the channels is determined by situational demands. Furthermore, processing in a channel is regarded as superficial. Increased allocation of processing to the superficial level was manipulated by the use of modality specific distractors and conditions of ‘supracapacity load’. Transformation of information from the visual to the auditory channel was controlled by the use of one mixed-mode and one single-mode experiment. Thirty subjects participated in the mixed-mode experiment and 60 in the single-mode experiment. Both experiments employed an identical distraction task, intervening presentation and free recall of the to-be-remembered items. The results confirmed the predictions of (a) modality specific distraction, (b) supracapacity performance decrement, (c) a larger distraction effect for the auditory channel and (d) transformation effects in the single-mode experiment.     

Alcoholism risk and the P300 event-related brain potential: modality, task, and gender effects

The P300 event related potential (ERP) was elicited from young adults at low- (LR) and high-risk (HR) for alcoholism (n = 24/risk group), with equal numbers of male and female subjects employed. The effects of stimulus modality, task difficulty, and gender were assessed with analogous auditory and visual paradigms (tone location/head rotation and tone matching/shape matching). Although task performance was generally comparable across risk groups, LR subjects produced smaller P300 amplitudes than HR subjects for the visual matching tasks. No consistent risk group P300 latency effects were obtained. Gender, task difficulty, and scalp topography differentially modulated the risk group outcomes across paradigms. These findings suggest that P300 amplitude reflects risk-for-alcoholism in male and female young adults, but the specific task conditions and electrode location affect the strength of risk group differences.     

Limited generalisation of changes in attentional bias following attentional bias modification with the visual probe task

Although attentional bias modification (ABM) can change anxiety, recent studies failed to replicate such effects, possibly because the visual probe ABM failed to induce changes in attentional bias (AB). We investigated whether visual probe ABM generalised to different measures of AB besides the visual probe task (VPT), and thus whether ABM genuinely changes attentional processing. We trained participants (N?=?60) to either attend towards or away from angry facial expressions, and we examined training effects on the dot probe task, the exogenous cueing task, and the visual search task. We found a small change in AB in the VPT, but this effect did not transfer to the exogenous cueing task or the visual search task. Our study shows that ABM does not necessarily lead to generalised effects on AB. This finding can be explained by the poor psychometric properties of the AB measures.     

The beneficial effects of additional task load, positive affect, and instruction on the attentional blink

The attentional blink reflects the impaired ability to identify the 2nd of 2 targets presented in close succession--a phenomenon that is generally thought to reflect a fundamental cognitive limitation. However, the fundamental nature of this impairment has recently been called into question by the counterintuitive finding that task-irrelevant mental activity improves attentional blink performance (C. N. L. Olivers & S. Nieuwenhuis, 2005). The present study found a reduced attentional blink when participants concurrently performed an additional memory task, viewed pictures of positive affective content, or were instructed to focus less on the task. These findings support the hypothesis that the attentional blink is due to an overinvestment of attentional resources in stimulus processing, a suboptimal processing mode that can be counteracted by manipulations promoting divided attention.     

The modality effect of ego depletion: Auditory task modality reduces ego depletion

An initial act of self‐control that impairs subsequent acts of self‐control is called ego depletion. The ego depletion phenomenon has been observed consistently. The modality effect refers to the effect of the presentation modality on the processing of stimuli. The modality effect was also robustly found in a large body of research. However, no study to date has examined the modality effects of ego depletion. This issue was addressed in the current study. In Experiment 1, after all participants completed a handgrip task, one group's participants completed a visual attention regulation task and the other group's participants completed an auditory attention regulation task, and then all participants again completed a handgrip task. The ego depletion phenomenon was observed in both the visual and the auditory attention regulation task. Moreover, participants who completed the visual task performed worse on the handgrip task than participants who completed the auditory task, which indicated that there was high ego depletion in the visual task condition. In Experiment 2, participants completed an initial task that either did or did not deplete self‐control resources, and then they completed a second visual or auditory attention control task. The results indicated that depleted participants performed better on the auditory attention control task than the visual attention control task. These findings suggest that altering task modality may reduce ego depletion.     

Motivation effects of attributions, expectancy, and achievement motivation during the learning of a novel motor task

Several cognitive motivational theories including achievement motivation, attribution theory, and a test of expectancy for future success were linked to explain and predict psychomotor performance. Sixty high- and 60 low-need-achieving male high school students were randomly placed into success and failure feedback conditions, and performance scores on a lever-positioning apparatus were assessed. Following each block of performance trials, fictitious feedback in the form of success and failure information was given, and then each subject rated attribution and expectancy questionnaires. Expectancies for future performance improved more following success than after failure and were generally predicted by attributions to stable elements. Although trends were present, performance scores were unaffected by these cognitive beliefs. However, a significant prediction of performance was obtained when stepwise multiple regression procedures were used with constant error as the criterion variable. The factors of expectancy and luck significantly predicted performance.     

Location-specific attentional control is also possible in the Simon task

Goal-directed behavior usually requires mental control that directs attention to task-relevant information and ignores irrelevant information. For investigating how flexible this mechanism is, researchers have varied the proportion of congruent trials depending on some context, such as stimulus location. The corresponding studies revealed that attentional control indeed adapts to location-specific demands. However, until now, this flexibility has only been demonstrated for the Eriksen flanker task and for the Stroop task but not for the Simon task. Therefore, a Simon-task experiment was conducted in the present study, where the proportion of congruent trials differed for stimuli appearing above or below fixation, respectively. As a result, a reliable interaction between congruency and stimulus location was found. This demonstrates, for the first time, that location-specific control also is possible in the Simon task.     

Adult age differences in attentional selectivity and capacity

Abstract

This paper reviews empirical research on adult age differences in the use of attention during visual search and classification tasks. This research suggests that the selective aspect of attention, in the sense of the ability to discriminate relevant and irrelevant information, is relatively resistant to age-related change. The capacity aspect of attention, in the sense of the limited processing resources that underlie task performance, appears to undergo age-related decline. Questions remain, however, regarding whether capacity-reduction explanations of age differences in cognitive performance have any advantages over explanations based on task complexity. Recent analyses of ageing and attention emphasise the potential contribution of formal models of cognitive performance.     

The attentional demands of negation in a memory-scanning task

Subjects were run in a Sternberg recognition memory task modified to occasionally require a transformation prior to response. The transformation was similar to logical negation since onplus or nontransformed trials subjects responded "yes" if the probe was from the current memory set and "no" otherwise, while onminus or transformed trials subjects responded "no" to memory set probes and "yes" to nonmemory set probes. Two models proposed to account for the effects of logical negation were compared: The encoding and comparison model predicts that logical negation requires an additional processing stage, while the capacity sharing model argues that negation adds a processing stage and also retards the rate of memory search. The results indicated that minus probes had 50% larger mean reaction time by set size slopes than the corresponding plus probes. This finding offers clear support for the capacity sharing model.     

The role of attentional networks in voluntary task switching

Coordination of task choice and performance in multitask environments likely involves attentional processes. Subjects completed the Attention Network Test (ANT) and a voluntary task-switching procedure. Task choice, but not task performance, was correlated with the executive score from the ANT, with higher switch probabilities for subjects with more efficient executive control networks. Task performance was correlated with the alerting score, with larger response time switch costs for subjects with larger alerting scores. The dissociation of task choice and task performance measures in terms of the pattern of correlations with attentional networks suggests that these two measures may reflect different cognitive processes engaged in voluntary task switching.     

Local muscular fatigue and attentional processes in a fencing task

Study of the effects of brief exercise on mental processes by Tomporowski and Ellis (1986) has shown that moderate muscular tension improves cognitive performance while low or high tension does not. Improvements in performance induced by exercise are commonly associated with increase in arousal, while impairments are generally attributed to the effects of muscular or central fatigue. To test two hypotheses, that (1) submaximal muscular exercise would decrease premotor time and increase would increase the attentional and preparatory effects observed in premotor time 9 men, aged 20 to 30 years, performed an isometric test at 50% of their maximum voluntary contraction between blocks of a 3-choice reaction-time fencing task. Analysis showed (1) physical exercise did not improve postexercise premotor time, (2) muscular fatigue induced by isometric contractions did not increase motor time, (3) there was no effect of exercise on attentional and preparatory processes involved in the postexercise choice-RT task. The invalidation of hypotheses was mainly explained by disparity in directional effects across subjects and by use of an exercise that was not really fatiguing.