Laura P. McAvinue

Enhancing the Sensitivity of a Sustained Attention Task to Frontal Damage: Convergent Clinical and Functional Imaging Evidence

Despite frequent reports of poor concentration following traumatic brain injury, studies have generally failed to find disproportionate time-on-task decrements using vigilance measures in this patient group. Using a rather different definition, neuropsychological and functional imaging research has however linked sustained attention performance to right prefrontal function – a region likely to be compromised by such injuries. These studies have emphasized more transitory lapses of attention during dull and ostensibly unchallenging activities. Here, an existing attention measure was modified to reduce its apparent difficulty or ‘challenge’. Compared with the standard task, its capacity to discriminate traumatically head-injured participants from a control group was significantly enhanced. Unlike existing functional imaging studies, that have compared a sustained attention task with a no-task control, in study 2 we used positron emission tomography to contrast the two levels of the same task. Significantly increased blood flow in the dorsolateral region of the right prefrontal cortex was associated with the low challenge condition. While the results are discussed in terms of a frontal system involved in the voluntary maintenance of performance under conditions of low stimulation, alternative accounts in terms of strategy application are considered.

Impaired sustained attention and error awareness in traumatic brain injury: Implications for insight

The processes of error awareness and sustained attention were investigated in 18 traumatic brain injury (TBI) individuals and 16 matched control participants. In Experiment 1, we found that: (1) in comparison to controls, TBI participants displayed reduced sustained attention and awareness of error during the Sustained Attention to Response Task; (2) degree of error awareness was strongly correlated with sustained attention capacity, even with severity of injury partialed out; and (3) that error feedback significantly reduced errors. We replicated the finding of a correlation between error awareness and sustained attention capacity in Experiment 2 with a separate sample of 19 TBI participants and 20 controls. We conclude that TBI leads to impaired sustained attention and error awareness. The finding of a significant relationship between these two deficits in TBI suggests there may be a link between these two processes. Feedback on error improves sustained attention performance of control and TBI participants.

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 35:747–58, 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 97:523–547, 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.

Measuring motor imagery ability : A review

The internal nature of motor imagery makes the measurement of motor imagery ability a difficult task. In this review, we describe and evaluate existing measures of motor imagery ability. Following Jeannerod (1994, 1997) we define motor imagery in terms of imagined movement from the first person perspective. We describe how explicit motor imagery ability can be measured by questionnaire and mental chronometry, and how implicit motor imagery ability can be measured through prospective action judgement and motorically driven perceptual decision paradigms. Future research should be directed towards a theoretical analysis of motor imagery ability, the improvement of existing questionnaires and the development of new ones, and the standardisation of existing paradigms.

An evaluation of a working memory training scheme in older adults

Working memory is a cognitive process that is particularly vulnerable to decline with age. The current study sought to evaluate the efficacy of a working memory training scheme in improving memory in a group of older adults. A 5-week online training scheme was designed to provide training in the main components of Baddeley’s (2000) working memory model, namely auditory and visuospatial short-term and working memory. A group of older adults aged between 64 and 79 were randomly assigned to a trainee (n = 19) or control (n = 17) group, with trainees engaging in the adaptive training scheme and controls engaging in a non-adaptive version of the program. Before and after training and at 3- and 6-month follow-up sessions, trainees and controls were asked to complete measures of short-term and working memory, long-term episodic memory, subjective ratings of memory, and attention and achievement of goals set at the beginning of training. The results provided evidence of an expansion of auditory short-term memory span, which was maintained 6 months later, and transfer to long-term episodic memory but no evidence of improvement in working memory capacity per se. A serendipitous and intriguing finding of a relationship between time spent training, psychological stress, and training gains provided further insight into individual differences in training gains in older adults.

Measuring Visual Imagery Ability: A Review

The internal nature of visual imagery makes the measurement of visual imagery ability a difficult task. In this review, we describe and evaluate the available measures of visual imagery ability. Several questionnaires of vividness, control, and preference have received favorable psychometric evaluations but these were not created on the basis of a theoretical analysis of imagery ability. Recent development of questionnaires has taken account of theoretical advances. Future research should continue in this vein. Objective tests of spatial ability may not be as appropriate as theory-driven visual imagery tests, as measures of visual imagery ability. The latter should be standardized. The well-known finding of a lack of relationship between subjective and objective imagery measures has been challenged by recent findings. Before this relationship can be fully examined, current measurement should be improved.

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.

Individual differences in response to phantom limb movement therapy

Purpose. Phantom limb pain (PLP) is a distressing condition experienced by many amputees. The purpose of this study was to investigate whether motor imagery could be used to treat PLP. Method. Four single case studies were conducted. The participants kept a pain diary in which they recorded the intensity of their PLP during a baseline period, general motor imagery training, phantom limb movement therapy and a follow-up period. Qualitative and quantitative (i.e. interrupted time series) analyses were employed to determine whether phantom limb movement therapy had a significant effect on PLP intensity. Results. Phantom limb movement therapy significantly reduced intensity of PLP in one participant. One participant gained occasional relief by doing phantom limb movement therapy exercises but did not experience an overall reduction in PLP intensity. The third participant did not experience any relief and the fourth participant reported experiencing the re-emergence of an old pain. Conclusion. The results display individual differences in response to phantom limb movement therapy. Individual differences are discussed in the context of motor imagery ability and the phantom limb phenomenon as a multi-dimensional disorder.

Relationship between Visual and Motor Imagery

The relationship between visual and motor imagery was investigated by administering a battery of visual and motor imagery measures to a sample of 101 men (n = 49) and women (n = 52), who ranged in age from 18 to 59 (M=34.5, SD=12.6). A principal components analysis applied to the correlation matrix indicated four underlying components, which explained 62.9% of the variance. The components were named Implicit Visual Imagery Ability, Self-report of Visual and Motor Imagery, Implicit Motor Imagery Ability, and Explicit Motor Imagery Ability. These results suggested a dissociation between visual and motor imagery although visual and motor imagery were associated as self-reports and there were correlations among particular measures.

A Componential Analysis of Visual Attention in Children With ADHD

Objective: Inattentive behaviour is a defining characteristic of ADHD. Researchers have wondered about the nature of the attentional deficit underlying these symptoms. The primary purpose of the current study was to examine this attentional deficit using a novel paradigm based upon the Theory of Visual Attention (TVA). Method: The TVA paradigm enabled a componential analysis of visual attention through the use of a mathematical model to estimate parameters relating to attentional selectivity and capacity. Children’s ability to sustain attention was also assessed using the Sustained Attention to Response Task. The sample included a comparison between 25 children with ADHD and 25 control children aged 9-13. Results: Children with ADHD had significantly impaired sustained attention and visual processing speed but intact attentional selectivity, perceptual threshold and visual short-term memory capacity. Conclusion:The results of this study lend support to the notion of differential impairment of attentional functions in children with ADHD.