Marc Obonsawin

Subjective experience and the attentional lapse: Task engagement and disengagement during sustained attention

Three experiments investigated the relationship between subjective experience and attentional lapses during sustained attention. These experiments employed two measures of subjective experience (thought probes and questionnaires) to examine how differences in awareness correspond to variations in both task performance (reaction time and errors) and psycho-physiological measures (heart rate and galvanic skin response). This series of experiments examine these phenomena during the Sustained Attention to Response Task (SART, Robertson, Manly, Adrade, Baddeley, & Yiend, 1997). The results suggest we can dissociate between two components of subjective experience during sustained attention: (A) task unrelated thought which corresponds to an absent minded disengagement from the task and (B) a pre-occupation with ones task performance that seems to be best conceptualised as a strategic attempt to deploy attentional resources in response to a perception of environmental demands which exceed ones ability to perform the task. The implications of these findings for our understanding of how awareness is maintained on task relevant material during periods of sustained attention are discussed.

Task unrelated thought whilst encoding information

Task unrelated thought (TUT) refers to thought directed away from the current situation, for example a daydream. Three experiments were conducted on healthy participants, with two broad aims. First, to contrast distributed and encapsulated views of cognition by comparing the encoding of categorical and random lists of words (Experiments One and Two). Second, to examine the consequences of experiencing TUT during study on the subsequent retrieval of information (Experiments One, Two, and Three). Experiments One and Two demonstrated lower levels of TUT and higher levels of word-fragment completion whilst encoding categorical relative to random stimuli, supporting the role of a distributed resource in the maintenance of TUT. In addition the results of all three experiments suggested that experiencing TUT during study had a measurable effect on subsequent retrieval. TUT was associated with increased frequency of false alarms at retrieval (Experiment One). In the subsequent experiments TUT was associated with no advantage to retrieval based on recollection, by manipulating instructions at encoding (Experiment Two), and/or at retrieval (Experiment Three). The implications of the results of all three experiments are discussed in terms of recent accounts of memory retrieval and conscious awareness.

Mind-wandering and dysphoria.

Mind-wandering shares a number of important similarities with thinking in depression. This experiment examines whether mind-wandering provides a useful marker of cognition in dysphoria during a word learning task. Dysphoria was associated with more accessible mind-wandering when attempting to encode verbal items. In addition, in the dysphoric population, periods when the mind wandered led to greater decoupling from task-relevant processing as indexed by slower response times, and greater physiological arousal, as indexed by faster heart rates. In the general population, periods of mind-wandering when attempting to encode information were associated with poor retrieval and high skin conductance. Finally, the extent to which mind-wandering was associated with poor retrieval was associated with an individuals’ latency to retrieve specific autobiographical memories from outside the laboratory. These results provide strong evidence for the utility of mind-wandering as a marker for depressive thinking and suggest a number of important implications for therapy for depression.

The Executive Decline Hypothesis of Cognitive Aging: Do Executive Deficits Qualify as Differential Deficits and Do They Mediate Age-Related Memory Decline?*

This paper reports the results of two studies which investigated whether aging is associated with a differential deficit in executive function, compared with deficits in general cognitive ability (Wechsler Adult Intelligence Scale-Revised performance). Further, the studies investigated the specificity of the executive decline hypothesis of memory and aging by examining whether declines in executive function mediate age-related memory decline over and above the variance in memory accounted for by general cognitive ability. The results of Study 1 showed no consistent evidence of a differential decline in executive function among a sample of participants aged between 18 and 75 years. The results of Study 2 indicated a differential decline in one indicator of executive function, the Modified Card Sorting Test, among an older sample aged between 60 and 89 years. Both studies demonstrated that measures of executive function accounted for age-related variance in free recall, recognition, and serial recall, even after controlling for general cognitive ability. However, in Study 1, once variance attributed to speed of processing was taken into account, executive function did not contribute further to the age-related variance.

Task unrelated thought: the role of distributed processing

Task unrelated thought (TUT) refers to thought directed away from the current situation; for example, a day dream. Encapsulated models of cognition propose that qualitative changes in consciousness, i.e., the production of TUT, can be explained in terms of changes in the quantity of resources deployed for task completion. In contrast, distributed models of cognition emphasize the importance of holistic processes in the generation and maintenance of task focus and are consistent with the effects of higher order variables such as schemata. Three experiments were conducted on healthy participants using a categorical stimulus organization to contrast distributed and encapsulated views of cognition. Experiments 1 and 2 showed that despite the increased difficulty of the alphabetical verbal fluency task fewer TUTs were produced during category fluency condition. Experiment 3 replicated the categorical suppression of TUT while encoding and recalling information in a memory task. The results of these three experiments support the predictions derived from models of cognition emphasizing the importance of stimulus organization in the generation and maintenance of task focus and have potential importance for the scientific evaluation of cognition.

Seeing yourself in a positive light: Brain correlates of the self-positivity bias

Individuals are found to have better recall for self-referent information than other types of information. However, attribution research has shown that self-reference is highly correlated with emotional valence. The present study attempted to identify and separate the processing of self-reference and emotional valence using ERPs. Participants performed a two-choice task, judging the self-referential content of positive and negative words. Reaction times revealed an interaction between self-reference and emotional valence. Faster responses occurred after self-positive and non-self negative words as compared to self-negative and non-self-positive words. A similar interaction was identified in ERP waveforms in the time range of the N400 component at fronto-central electrode sites, with larger N400 amplitudes for words outwith the self-positivity bias. Thus, the size of the N400 may indicate the extent to which information is discrepant with the individuals self-concept.

Frontal lobe impairment in schizophrenia: relationship to intellectual functioning

Schizophrenic subjects (N = 48) and individually matched healthy controls were administered the Verbal Scale of the Wechsler Adult Intelligence Scale (VIQ) and a test of verbal fluency. The verbal fluency and VIQ scores of the schizophrenic subjects were significantly lower than the scores of the control subjects. An additional sample of healthy subjects (N = 144) was used to generate a regression equation for the prediction of verbal fluency scores from Verbal IQ and age. The verbal fluency scores obtained by the schizophrenic subjects were significantly lower than the scores predicted from the regression equation, whereas a significant difference was not obtained in the matched controls. These results provide further evidence of frontal lobe dysfunction in schizophrenia.

Performance on tests of frontal lobe function reflect general intellectual ability

Recent studies have indicated that performance on tests of frontal lobe function are highly associated with general intellectual ability (g). Some authors have even claimed that the available evidence does not support a more specific account of frontal lobe function than to provide a general intellectual function for the performance of goal directed tasks. We examined the relationship between performance on the WAIS-R (as a measure of g) and performance on standard tests of frontal lobe function in 123 healthy individuals. Our results demonstrate that in healthy individuals (i) performance on the most popular tests of frontal lobe function shares significant variance, and (ii) a large proportion of that shared variance is highly associated with performance on the Wechsler Adult Intelligence Scales-Revised (WAIS-R), so that the tests are similar to the extent that they measure g. Performance on the Modified Card Sorting Test (MCST), however, is not related to g. The results support the claim that many tests of frontal lobe function measure primarily a non-specific intellectual function but also indicate that some tests, like the MCST, may be assessing more specific cognitive operations.

The effects of block duration and task demands on the experience of task unrelated thought

Evidence indicates that the degree to which attention can be maintained upon the task in hand depends upon both the type and duration of the task. Two experiments investigated the relationship between task irrelevant thinking and block duration in two types of task. In Experiment One, a vigilance task was compared to a fluency task and in Experiment Two a verbal encoding task was compared to a fluency task. In both tasks we investigated the hypothesis that block duration mediated changes in thinking would be smallest for tasks which rely heavily on controlled processing (the fluency task). Results were consistent with expectations and indicated that the report of thoughts with no relationship to the task in hand increased with block duration in the vigilance task (Experiment One) and the verbal encoding task (Experiment Two). In neither experiment did block length effect thinking during the fluency task. These results are broadly consistent with the assertion that tasks that cannot be readily automated, maintain attention upon the task at hand in a superior fashion as the duration of the block increases. The implications of these results for our understanding of the process responsible for our conscious awareness of a stimulus and our ability to plan and anticipate events are discussed.

The effects of improving sleep on mental health (OASIS): a randomised controlled trial with mediation analysis

Summary Background Sleep difficulties might be a contributory causal factor in the occurrence of mental health problems. If this is true, improving sleep should benefit psychological health. We aimed to determine whether treating insomnia leads to a reduction in paranoia and hallucinations. Methods We did this single-blind, randomised controlled trial (OASIS) at 26 UK universities. University students with insomnia were randomly assigned (1:1) with simple randomisation to receive digital cognitive behavioural therapy (CBT) for insomnia or usual care, and the research team were masked to the treatment. Online assessments took place at weeks 0, 3, 10 (end of therapy), and 22. The primary outcome measures were for insomnia, paranoia, and hallucinatory experiences. We did intention-to-treat analyses. The trial is registered with the ISRCTN registry, number ISRCTN61272251. Findings Between March 5, 2015, and Feb 17, 2016, we randomly assigned 3755 participants to receive digital CBT for insomnia (n=1891) or usual practice (n=1864). Compared with usual practice, the sleep intervention at 10 weeks reduced insomnia (adjusted difference 4·78, 95% CI 4·29 to 5·26, Cohens d=1·11; p<0·0001), paranoia (−2·22, −2·98 to −1·45, Cohens d=0·19; p<0·0001), and hallucinations (−1·58, −1·98 to −1·18, Cohens d=0·24; p<0·0001). Insomnia was a mediator of change in paranoia and hallucinations. No adverse events were reported. Interpretation To our knowledge, this is the largest randomised controlled trial of a psychological intervention for a mental health problem. It provides strong evidence that insomnia is a causal factor in the occurrence of psychotic experiences and other mental health problems. Whether the results generalise beyond a student population requires testing. The treatment of disrupted sleep might require a higher priority in mental health provision. Funding Wellcome Trust.