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Oliver H Turnbull

Publications and source records attributed to Oliver H Turnbull.

16 recordsLinked to original sources
PubMed2006

A novel set-shifting modification of the iowa gambling task: flexible emotion-based learning in schizophrenia.

Although it might seem that people with schizophrenia would perform poorly on measures of emotion-based learning, several studies have shown normal levels of performance on the Iowa Gambling Task (IGT; C. E. Y. Evans, C. H. Bowman, & O. H. Turnbull, 2005; L. M. Ritter, J. H. Meador-Woodruff, & G. W. Dalack, 2004; B. Shurman, W. P. Horan, & K. H. Nuechterlein, 2005; K. E. Wilder, D. R. Weinberger, & T. E. Goldberg, 1998). The present article describes a newly developed modification of the IGT involving initial familiarization with the basic contingency pattern then 3 periods of contingency shift. Control participants showed substantial gains during the later trials of each shift period. Analyzed in terms of positive symptoms, those with schizophrenia were little different from control participants. Those high in negative symptoms could perform the basic task but showed remarkably poor performances (no better than chance) in the shift phases, retaining a preference for decks that had previously been "good," even when they experienced substantial losses.

Adult↗
PubMed2005

Preserved complex emotion-based learning in amnesia.

An important role for emotion in decision-making has recently been highlighted by disruptions in problem solving abilities after lesion to the frontal lobes. Such complex decision-making skills appear to be based on a class of memory ability (emotion-based learning) that may be anatomically independent of hippocampally mediated episodic memory systems. There have long been reports of intact emotion-based learning in amnesia, arguably dating back to the classic report of Claparede. However, all such accounts relate to relatively simple patterns of emotional valence learning, rather than the more complex contingency patterns of emotional experience, which characterise everyday life. A patient, SL, who had a profound anterograde amnesia following posterior cerebral artery infarction, performed a measure of complex emotion-based learning (the Iowa Gambling Task) on three separate occasions. Despite his severe episodic memory impairment, he showed normal levels of performance on the Gambling Task, at levels comparable or better than controls-including learning that persisted across substantial periods of time (weeks). Thus, emotion-based learning systems appear able to encode, and sustain, more sophisticated patterns of valence learning than have previously been reported.

Aged, 80 and over↗
PubMed2005

Artificial time constraints on the Iowa Gambling Task: the effects on behavioural performance and subjective experience.

In the last decade, the Iowa Gambling Task (IGT) has become a widely employed neuropsychological research instrument for the investigation of executive function. The task has been employed in a wide range of formats, from 'manual' procedures to more recently introduced computerised versions. Computer-based formats often require that responses on the task should be artificially delayed by a number of seconds between trials to collect skin-conductance data. Participants, however, may become frustrated when they want to select from a particular deck in the time-limited versions--so that an unintended emotional experience of frustration might well disrupt a task presumed to be reliant on emotion-based learning. We investigated the effect of the various types of Iowa Gambling Task format on performance, using three types of task: the classic manual administration, with no time limitations; a computerised administration with a 6-s enforced delay; and a control computerised version which had no time constraints. We also evaluated the subjective experience of participants on each task. There were no significant differences in performance, between formats, in behavioural terms. Subjective experience measures on the task also showed consistent effects across all three formats-with substantial, and rapidly developing, awareness of which decks were 'good' and 'bad.'

Adolescent↗
PubMed2005

Emotion-based learning and central executive resources: an investigation of intuition and the Iowa Gambling Task.

The role of emotion in complex decision-making can be assessed on the Iowa Gambling Task (IGT), a widely used neuropsychological measure that may tap a different aspect of executive function than that assessed by conventional measures. Most notably, the 'feeling' about which decks are good or bad, often described in relation to IGT performance, seems reminiscent of decision-making based on intuition-linked to a long history of research in decision-making contrasting the 'intuition' versus 'reasoning' styles of problem solving. To test the claim that the performance on the IGT relies more on emotion-based learning than conventional executive resources for normal performance, a group of participants completed the IGT simultaneously with one of two secondary-tasks, one of which (random number generation) is known to load executive resources. A third group performed the IGT with no secondary-task. If performance on the IGT requires the properties associated with intuitive operations, then participants should either show no disruption when completing a secondary-task, or at least show no selective disruption on a secondary-task that loads for executive function. The rate of learning in the three groups was not significantly different. This suggests that the sorts of cognitive resources loaded by traditional executive tasks such as random number generation do not overlap, in the cognitive architecture, with the emotion-based learning skills that are required for Iowa Gambling Task performance. The findings of the present study are also consistent with a previous claim of the Iowa group that emotion-based learning and working memory resources are doubly dissociable.

Cognition↗
PubMed2005

Negative emotions and anosognosia.

Patients with anosognosia fail to acknowledge, or feel distressed by, their disability. Given the recent suggestion that right (frontal) systems are selectively involved in negative emotions, it might be claimed that anosognosia results from a disruption in negative emotions. This is not consistent with the finding that some anosognosic patients exhibit substantial fluctuations in emotion, including the experience of negative emotions such as sadness. The present study investigates a patient (IW) with a right convexity lesion and anosognosia. He reported being frequently overcome by powerful emotions, especially sadness. IW was assessed on a self-report emotion questionnaire, where his reports were typically of higher levels of emotion than the control group. He was also assessed on the more indirect measure of Affective Story Recall. Here his pattern of emotional experience was similar to that of two control groups, one of which consisted of non-anosognosic patients with hemiparesis. His performance on Story Recall was notable in that he directed his emotions to a different 'object' to that of controls (other vs. self, respectively). These findings are not consistent with any claim that anosognosia results from an absence of negative emotions.

Aged↗
PubMed2005

Subjective awareness on the Iowa Gambling Task: the key role of emotional experience in schizophrenia.

The key role of emotion in complex decision-making is commonly assessed using the Iowa Gambling Task, and has recently been a substantial research topic in neuropsychology. However, the question of subjective experience on such emotion-based learning measures has yet to be fully investigated, largely because previous studies have focussed primarily on behavioral performance measures. The present study investigated subjective experience on the Gambling Task, using a more systematic and quantitative method than that previously employed: evaluating the ability of participants to 'interrogate' emotion-based learning systems. The study also investigated subjective experience in a population (people with schizophrenia) in whom the question of emotional awareness is of special interest. People with schizophrenia showed learning on the Gambling Task at levels entirely comparable with that of controls. Both groups of participants also showed substantial, and rapidly developing, awareness of which decks were 'good' and 'bad'. Importantly, greater awareness was a significant correlate of good performance on the Gambling Task, for both groups, suggesting that there may be greater conscious awareness of emotion-related information in complex decision-making than had previously been appreciated.

Adult↗
PubMed2004

Emotion-based learning on a simplified card game: the Iowa and Bangor Gambling Tasks.

The Iowa Gambling Task (IGT) has been widely used in the assessment of neurological patients with frontal lesions. Emphasis has been placed on the complexity of the task (i.e., four decks of varying contingency pattern) with the suggestion that the participant must use emotion-based learning to deal with a complex decision-making process. The present study used a single deck card game (the Bangor Gambling Task, BGT), matched in many respects with the Iowa Gambling Task, in which the contingencies varied over time (gradually becoming worse for the participant) rather than across deck (as in the IGT). Forty participants performed both tasks. Performance on the tasks showed many similarities, with participants showing a comparable pattern of incremental learning on both tasks, reaching an analogous final level of performance. More importantly, there was a high correlation (r(2) = .93) in performance between the two tasks, the most salient feature of which was that virtually every participant who fell below categorisation of impaired IGT performance, also did very poorly on the BGT. These findings bear on the question of whether arguments about the 'complexity' of the Iowa Gambling Task necessarily explain why it appears to require emotion-based learning. The Bangor Gambling Task might also be a useful tool for clinical neuropsychologists, in the assessment of patients with executive dysfunction-given that the task is easier and quicker to administer than the Iowa Gambling Task, but appears to share the same performance features.

Adult↗
PubMed2004

Paradoxical effects of education on the Iowa Gambling Task.

Suitable normative information on the Iowa Gambling Task (IGT) is not currently available, though it is clear that there is great individual variability in performance on this assessment tool. Given that the task is presumed to measure the emotion-based learning systems that are thought to form the biological basis of 'intuition,' there is some reason to think that education (especially tertiary education) might explicitly de-emphasise the role of emotion-based learning in decision-making. This suggests the paradoxical finding that better-educated participants should show poorer performance on the IGT. We recruited 30 participants (all female, all aged 18-25) to participate in a 'real money' version of the IGT. There was no significant difference in performance in blocks 1-3 of the task (trials 1-60). However, there was a substantial effect of education on the final two blocks (trials 61-100), such that the less-well-educated participants produced twice as much of an improvement over baseline as did their university-educated colleagues. A range of possible explanations for this remarkable finding are discussed. The most likely appears to be that tertiary education specifically discourages the use of emotion-based learning systems in decision-making. These findings bear on the extent to which education has a role to play in our reliance on cognition and emotion in decision-making, including the likely role of education in the generation and maintenance of false beliefs.

Adolescent↗
PubMed2004

A positive emotional bias in confabulatory false beliefs about place.

Some neurological patients with medial frontal lesions exhibit striking confabulations. Most accounts of the cause of confabulations are cognitive, though the literature has produced anecdotal suggestions that confabulations may not be emotionally neutral, having a ('wish-fulfilment') bias that shapes the patient's perception of reality in a more affectively positive direction. The present study reviewed every case (N = 16) of false beliefs about place reported in the neuroscientific literature from 1980 to 2000, with blind raters evaluating the 'pleasantness' of the patient's actual and confabulated locations. In each case the confabulated location was evaluated as more pleasant. This striking finding supports the claim that there may be a systematic affective bias in the false beliefs held by neurological patients with confabulation.

Adult↗
PubMed2003

Real versus facsimile reinforcers on the Iowa Gambling Task.

The Iowa Gambling Task (([Bechara et al., 1994]) is an effective neuropsychological tool for the assessment of 'real-life' decision-making in a laboratory environment. It has been employed in a wide range of circumstances, though researchers have sometimes employed real money reinforcers instead of the facsimile (or 'monopoly'-type) money used by. The present study investigated whether the type of reinforcer produced any differences in performance. There were no significant differences between the two conditions, though the Facsimile Money condition produced a greater range (and a higher standard deviation) than the Real Money condition. This finding is especially important when considering the Gambling Task as a tool in clinical neuropsychology--where there are risks, at the individual subject level, of both false positive and false negative classification errors.

Adult↗
PubMed2003

Direct versus indirect emotional consequences on the Iowa Gambling Task.

The Iowa Gambling Task has been widely used in the assessment of neurological patients with ventro-mesial frontal lesions. The Iowa Group has claimed that the Gambling Task is too complex for participants to follow using cognition alone, so that participants must rely on emotion-based learning systems (somatic markers). The present study investigates whether similar tasks can be performed without direct somatic markers. In a 'Firefighter' task closely matched to the classic Gambling Task, participants evaluate the performance of others--so that they experience reward and punishment indirectly. In contrast to the gradual improvement in performance seen on the classic Iowa Gambling Task, participants on the Firefighter Task showed no learning effect, mirroring the performance of patients with ventro-mesial frontal lesions, and suggesting that the task is very difficult to perform without direct somatic marker information. The use of this task as empirical measure of 'empathy' are discussed.

Adult↗
PubMed2002

Agnosia for object orientation: naming and mental rotation evidence.

We have previously reported the performance of a patient (NL) who could recognize objects, but appeared to lack knowledge of their orientation. These results were interpreted as evidence that NL had isolated access to a viewpoint-independent (ventral stream) object recognition system. However, because NL's responses on naming tasks were not timed, it was not possible to establish whether he showed the same pattern of reaction time performance generally accepted as evidence of a 'mental rotation' strategy in neurologically normal subjects. Here we report NL's performance on two reaction time tasks, testing his ability to transform images when naming, and discriminating between rotated mirror image objects. As predicted, and in contrast to normal volunteers, NL showed no 'mental rotation' effect in his naming of misoriented objects. Paradoxically, he performed well on a traditional Shepard and Metzler mental rotation task. He also showed a normal orientation effect when dealing with misoriented faces. These findings offer further support for viewpoint-independent theories of object recognition, and bolster the claim that object orientation knowledge can be regarded as, in some respects, a special class of spatial information.

Aged↗
PubMedDate not supplied

Central executive secondary tasks in object recognition: an analogue of the unusual views deficit in the neurologically normal?

The particular problem of recognition from unusual viewpoints, may well involve a substantial problem-solving component and employ frontal/central executive resources. The present study investigates this question using a dual-task technique. In Experiment 1, the reliability of an unusual views effect was demonstrated. Experiment 2 showed that a central executive secondary task selectively disrupts unusual views recognition. These results are discussed in the context of existing lesion and functional imaging findings.

Adolescent↗
PubMedDate not supplied

2D but not 3D: pictorial-depth deficits in a case of visual agnosia.

Patients with visual agnosia exhibit acquired impairments in visual object recognition, that may or may not involve deficits in low-level perceptual abilities. Here we report a case (patient DM) who after head injury presented with object-recognition deficits. He still appears able to extract 2D information from the visual world in a relatively intact manner; but his ability to extract pictorial information about 3D object-structure is greatly compromised. His copying of line drawings is relatively good, and he is accurate and shows apparently normal mental rotation when matching or judging objects tilted in the picture-plane. But he performs poorly on a variety of tasks requiring 3D representations to be derived from 2D stimuli, including: performing mental rotation in depth, rather than in the picture-plane; judging the relative depth of two regions depicted in line-drawings of objects; and deciding whether a line-drawing represents an object that is 'impossible' in 3D. Interestingly, DM failed to show several visual illusions experienced by normals (Muller-Lyer and Ponzo), that some authors have attributed to pictorial depth cues. Taken together, these findings indicate a deficit in achieving 3D intepretations of objects from 2D pictorial cues, that may contribute to object-recognition problems in agnosia.

Adult↗
PubMedDate not supplied

Hemispheric asymmetry for global and local processing: language is less important than one might think.

There have been consistent findings of hemispheric asymmetry in global/local processing, in both neurological patients and the neurologically normal. However, with one exception, these studies have used purely linguistic stimuli (letters made up of letters). The present study investigates lateral asymmetry for processing of global/local objects with less "linguistic" properties (e.g., letters made up of shapes, and shapes made up of letters) using a change detection paradigm. In each case the classic pattern of hemispheric asymmetry was found. These results are discussed in the context of the relative importance of hemispheric asymmetry for both global/local and linguistic information.

Adolescent↗