School of Psychology

Experience Excellence Studying People


Dr Dinkar Sharma

Senior Lecturer in Psychology

 Dinkar Sharma

 

Research interests

    My main areas of current research are:

  • EMOTION. Using the Stroop task and Posner's cueing paradigm I have looked at various factors that moderate the pattern of disruption from emotional stimuli. The major issue here is the role of emotional interference in cognitive control. Our hypothesis is that emotional interference is the result of systems that disengages attention from the task for a brief period of time. This has been implemented this in a recent model (see Wyble, Sharma, & Bowman, in press).
  • ADDICTION: I am interested in the processing of addiction (in particular, alcohol and smoking) related stimuli. This research aims to develop objective measures, test cognitive models, and investigate techniques that can be used to reduce the impact of these stimuli.
  • ATTENTION: Testing cognitive models of selective attention (e.g. connectionists, translation models) by varying properties of the stimulus as well as the modality of the response.

I would welcome applications from potential doctoral students in these areas.

Key publications

Sharma D. & Money S. (2010). Carryover effects to addiction-associated stimuli in a group of marijuana and cocaine users. Journal of Psychopharmacology, 24(9), 1309-1316.

Sharma D., Booth R. Huguet P., & Brown R. (2010). The temporal dynamics of social facilitation in the Stroop task. Psychonomic Bulletin & Review, 17, 52-58.

Cane, J.E., Sharma, D., & Albery, I.P. (2009). The addiction Stroop task: examining the fast and slow effects of smoking and marijuana-related cues. Journal of Psychopharmacology, 23(5), 510-519.

Van Hooff, J.C., Dietz, K.C., Sharma, D. et al. (2008). Neural correlates of intrusion of emotion words in a modified Stroop task. International Journal of Psychophysiology, 67(1), 23-34.

Wyble, B.P. Sharma, D. & Bowman, H. (2008). Strategic regulation of cognitive control by emotional salience: A neural network model. Cognition & Emotion, 22(6). 1019-1051.

 

 

Also view these in the Kent Academic Repository
Articles

    Cane, J.E. and Sharma, D. and Albery, I.P. (2009) The addiction Stroop task: examining the fast and slow effects of smoking and marijuana-related cues. Journal of Psychopharmacology, 23 (5). pp. 510-519. ISSN 0269-8811.

    Abstract

    Research has shown that attentional bias toward smoking-related stimuli is related to the maintenance of smoking behaviour and the chance of a relapse during a quit attempt. Effects of smoking attentional bias can occur both during smoking stimulus presentation (fast effect) and on stimuli that immediately follow smoking stimuli (slow effect). The current research builds on these findings by closely examining the temporal aspects of these fast and slow effects across groups of different smoking status. In Experiment 1 (n = 64), smokers, smokers attempting to quit (SATQ) and non-smokers completed an addiction Stroop task using smoking related, negative emotion and neutral stimuli. In Experiment 2 (n = 32), marijuana smokers and non-marijuana smokers completed an addiction Stroop task using marijuana and neutral stimuli. Results showed fast effects across all smoking groups (except non-smokers) and slow effects in SATQ and marijuana smokers. Furthermore, marijuana smokers showed slow effects over extended periods of time. Results also show a relationship between anxiety, nicotine dependence and attentional bias in SATQ. The implications of these findings are discussed.

    Cane, J.E. and Sharma, D. and Albery, I.P. (2009) The addiction Stroop task: examining the fast and slow effects of smoking and marijuana-related cues. Journal of Psychopharmacology, 23 (5). pp. 510-519. ISSN 0269-8811.

    Abstract

    Research has shown that attentional bias toward smoking-related stimuli is related to the maintenance of smoking behaviour and the chance of a relapse during a quit attempt. Effects of smoking attentional bias can occur both during smoking stimulus presentation (fast effect) and on stimuli that immediately follow smoking stimuli (slow effect). The current research builds on these findings by closely examining the temporal aspects of these fast and slow effects across groups of different smoking status. In Experiment 1 (n = 64), smokers, smokers attempting to quit (SATQ) and non-smokers completed an addiction Stroop task using smoking related, negative emotion and neutral stimuli. In Experiment 2 (n = 32), marijuana smokers and non-marijuana smokers completed an addiction Stroop task using marijuana and neutral stimuli. Results showed fast effects across all smoking groups (except non-smokers) and slow effects in SATQ and marijuana smokers. Furthermore, marijuana smokers showed slow effects over extended periods of time. Results also show a relationship between anxiety, nicotine dependence and attentional bias in SATQ. The implications of these findings are discussed.

    pdf
    Van Hooff, J.C. and Dietz, K.C. and Sharma, D. et al. (2008) Neural correlates of intrusion of emotion words in a modified Stroop task. International Journal of Psychophysiology, 67 (1). pp. 23-34. ISSN 0167-8760.

    Abstract

    Behavioural studies have demonstrated that the emotional Stroop task is a valuable tool for investigating emotion-attention interactions in a variety of healthy and clinical populations, showing that participants are typically more distracted by negative stimuli as compared to neutral or positive stimuli. The main aim of this study was to find and examine the neural correlates of this greater intrusion from negative emotional stimuli. Reliable reaction time (RT) and event-related potential (ER-P) data were collected from 23 participants who performed a manual emotional Stroop, task with short (40 ins) and long (500 ms) inter-trial intervals. In the short interval condition, participants were found to produce longer RTs for negative than neutral words, suggesting that these stimuli were more difficult to ignore. This RT effect disappeared in the long interval condition, although larger PI amplitudes were found for the negative words. This suggests that differences in early attention allocation may be unrelated to the degree of intrusion at the behavioural level. In addition, a larger negative slow wave around 300-700 ms post-stimulus was observed in the long interval condition, but only for those negative words that produced prolonged RTs as compared to their matched controls. This late and broadly distributed effect is believed to reflect suppression of meaning representations.

    Wyble, B.P. and Sharma, D. and Bowman, H. (2008) Strategic Regulation of Cognitive Control by Emotional Salience: A Neural Network Model. Cognition & Emotion, 22 (6). pp. 1019-1051. ISSN 0269-9931.

    Abstract

    We present a neural network model of stimulus processing, which uses a mechanism of adaptive attentional control to regulate the moment to moment deployment of attention according to both the demands of the current task, and the demands of emotionally salient information. This mechanism allows negative emotional information to reduce cognitive control to aid in the detection of threats, which produces a momentary withdrawal from the current task set to allow unbiased processing of available information. The combination of cognitive and emotional regulation of task set allows this model to address inter-trial aspects of emotional interference in colour naming. In particular, we focus on the nature of the emotional interference in colour naming (McKenna Sharma, 2004) as well as in word reading (Algom, Chajut, Lev, 2004) and show how this form of interference is functionally distinct from the classic Stroop effect. Our model addresses a range of findings in colour naming and word reading tasks and is informed by recent neuroimaging data concerning the interaction between the anterior cingulate and prefrontal cortices. The model is used to explore the interface between cognition and emotion with a series of predictions, including a qualitative distinction between state and trait forms of anxiety.

    Eilola, T.M. and Havelka, J. and Sharma, D. (2007) Emotional activation in the first and second language. Cognition and Emotion, 21 (5). pp. 1064 -1076. ISSN 0269-9931.

    Abstract

    Late Finnish-English bilinguals were presented with neutral, positive, negative and taboo words in a modified Stroop paradigm in both Finnish and English. Significant interference from negative and taboo words compared to neutral words was found in both languages, whereas positive words were not found to differ significantly from neutral words. Furthermore, no differences in the size of the interference were present between languages. This suggests that, for late bilinguals with good knowledge of their second language, the first (L1) and second (L2) language are equally capable of activating the emotional response to word stimuli representing threat, and thus interfering with the cognitive processes involved in responding to colour. This effect was equivalent for negative and taboo words.

    Parris, B. and Sharma, D. and Weekes, B. (2007) An optimal viewing position effect in the stroop task when only one letter is the color carrier. Experimental Psychology, 54 (4). pp. 273-280. ISSN 1618-3169.

    Abstract

    Coloring only a single letter in the Stroop task can result in a reduction or elimination of Stroop interference. The present experiments were designed to test whether this modulation of Stroop interference occurs at all letter positions. Specifically, we investigated whether Stroop interference was reduced when the colored letter occupied the optimal viewing position (OVP). The experiments show that Stroop interference is not reduced at the OVP ( Experiment 1) and that Stroop interference at the OVP is significantly greater than at other letter positions ( Experiments 1 and 2). This finding has important theoretical and methodological consequences for studies of automatic processing in visual word recognition

    Brosch, T. and Sharma, D. (2005) The role of fear-relevant stimuli in visual search: A comparison of phylogenetic and ontogenetic stimuli. Emotion, 5 (3). pp. 360-364. ISSN 1528-3542.

    Abstract

    It has been argued that phylogenetic fear-relevant stimuli elicit preattentive capture of attention. To distinguish between fear relevance and time of appearance in evolutionary history, the authors compare phylogenetic and ontogenetic fear-relevant and fear-irrelevant stimuli in a visual search task. The authors found no evidence for a special role of phylogenetic fear-relevant stimuli; it seems that fear relevance in general is more important than is the evolutionary age. The pattern of results indicates that attention toward threatening stimuli is mainly affected by a late component that prolongs the disengagement of attention.

    McKenna, F.P. and Sharma, D. (2004) Reversing the emotional Stroop effect: The role of fast and slow components. Journal of Experimental Psychology: Learning Memory and Cognition, 30 (2). pp. 382-392. ISSN 0278-7393.

    Jessop, D.C. and Rutter, D.R. and Sharma, D. et al. (2004) Emotion and adherence to treatment in people with asthma: An application of the emotional Stroop paradigm. British Journal of Psychology, 95 (Part 2). pp. 127-147. ISSN 0007-1269.

    Abstract

    This study explored whether an emotional Stroop paradigm might represent an appropriate means of assessing individuals' emotional representations of asthma. In addition, the opportunity was taken to investigate whether emotional representations of asthma, as assessed by this method, were associated with adherence to inhaled preventative medication. An asthma Stroop task was devised which comprised three sets of stimuli: asthma symptom words, general negative words, and neutral words. Three groups of participants were compared on their performance on this task: individuals with asthma, individuals without asthma, and individuals without asthma who had been primed about the condition. It was found that individuals with asthma experienced significantly more interference when colour-naming the asthma symptom words, but not when colour-naming the general negative words. Furthermore, their performance on the asthma Stroop task was associated with self-reported adherence levels. Specifically, individuals who reported the highest and lowest levels of adherence displayed more interference when colour-naming the asthma symptom words than individuals with intermediate levels of adherence. It is concluded that the emotional Stroop paradigm might provide an objective and sensitive means of assessing individuals' emotional representations of illness. Additionally, it is proposed that emotional responses to illness should be assessed and included in research designed to explain health behaviours and, furthermore, that such research should not assume that any relationship between emotional representations and health behaviours will be linear.

    Sharma, D. and Albery, I.P. and Cook, C. (2001) Methodological issues attached to the alcohol Stroop paradigm: a rejoinder to Cox, Pothos, Johnsen & Laberg. Addiction, 96 (10). pp. 1512-1514. ISSN 0965-2140.

    Sharma, D. and Albery, I.P. and Cook, C. (2001) Selective attentional bias to alcohol related stimuli in problem drinkers and non-problem drinkers. Addiction, 96 (2). pp. 285-295. ISSN 0965-2140.

    Abstract

    Aims. The issues explored in this study were whether a patient group of problem drinkers selectively attend to alcohol-related stimuli and the time course of any interference from alcohol-related stimuli in comparison with two control groups of non-problem drinkers. Design. A 3x2x2x5 factorial design was used. Drinking group (low, high and problem) and word order (alcohol-neutral, neutral-alcohol) were between-participant factors, and word type (alcohol, neutral) and presentation block (1-5) were within participant factors. Participants. Three groups were used, 20 participants from a local community alcohol Service (CAS) and 40 participants (student volunteers) in two control groups. The two control groups were differentiated as scoring high or low on the Alcohol Use Disorders Identification Test (AUDIT). Measurements. A modified computerized Stroop colour naming test was used to measure response latencies. Anxiety was measured using the State-Trait Anxiety Inventory. Findings. The CAS group showed significantly longer reaction times to respond to the colour of alcohol-related words than to neutral category words. Although the interference was smaller for the high AUDIT group it was significant. No significant interference was found in the low AUDIT group. There was no statistical evidence that the interference habituated in the three groups. Conclusions. The present study showed it is possible to use a modified Stroop task as a measure of implicit processing of alcohol stimuli. Despite the fact that all participants were asked to ignore the words, they were unable to do so. Alcohol-related words produced more interference than neutral category words in a group of problem drinkers and a control group of high alcohol drinkers.

    Sharma, D. and McKenna, F.P. (2001) The role of time pressure in the emotional Stroop task. British Journal of Psychology, 92 (3). pp. 471-481. ISSN 0007-1269.

    Abstract

    Although a wide range of methodologies have been employed in examining the emotional Stroop effect, little systematic investigation of these experimental manipulations has taken place. Two experiments were designed to investigate the role of time pressure in the emotional Stroop effect. It is shown that time pressure has an important role to play in determining not only the magnitude of the effect but also in whether it is possible to observe any effect at all.

    McKenna, F.P and Sharma, D. (2000) The pattern of disruption in the emotional Stroop task. International Journal of Psychology, 35 (3-4). pp. 371-371. ISSN 0020-7594.

Book Sections

    Albery, I.P. and Sharma, D. and Niyazi, A. et al. (2006) Introduction and methodologies. In: Munafò, Marcus Cognition and addiction. Oxford University Press. ISBN 9780198569305.

    Albery, I.P. and Sharma, D. and Niyazi, A. et al. (2006) Theoretical perspectives and approaches. In: Munafo, M. Cognition and Addiction. Oxford University Press, pp. 1-29. ISBN 9780198569299.

    Wyble, B. and Sharma, D. and Bowman, H. (2005) Modelling the slow emotional stroop effect: Suppression of cognitive control. In: Cangelosi, A. and Bugmann, Guido Modelling Language, Cognition and Action. Proceedings of the Ninth Neural Computation and Psychology Workshop, University of Plymouth, UK 8 - 10 September 2004. Progress in Neural Processing (16). World Scientific Publishing Company Pte Ltd, Singapore, pp. 291-300. ISBN 981-256-324-5.

    Abstract

    Our connectionist model provides a theoretical explanation for the existence of slow and fast emotional Stroop effects, and depicts them as independent but interacting phenomena. We build upon previous modelling work by Cohen et a] (1990) and Botvinick et al (2001) among others, and incorporate data that suggest a functional division of the Anterior Cingulate Cortex (ACC) into Cognitive and Affective Divisions. This work suggests that slow emotional Stroop effects are caused by activation of the affective portion of the ACC, which inhibits the Cognitive division, reducing top-down cognitive control on the subsequent trial.

Conference Items
Total publications in KAR: 37 [See all in KAR]
Information obtained from the Kent Academic Repository. The University of Kent official repository of academic activity.
More information about the Kent Academic Repository

Current research students

Sarah Hotham: Attention and eating behaviour: The role of cognitive control

Past research students

Dr Sharon Money (2010) Intentional and incidental Associative-Learning and the Emotional Stroop test

Dr James Cane (2009) Smoking attentional bias: The role of automaticity, affect and cognitive control

Dr Robert Booth (2009) Attentional Control Theory & Stroop interference: Selective attention deteriorates under stress

Dr Ana Fernandez  (2007) An investigation into how emotion orients attention

Dr Jason Tipples (1999) Deciding emotional meaning: A preattentive process?

2010

Sharma D. & Leader T. 
British Academy 
Charting the rise in anxious mood since 1969: a meta-analysis of trait anxiety across time and nations.

£7,500

2010

Sharma D.
University of Kent Faculty of Social Sciences 
The role of emotion in new word learning.

£990

2006

Hamilton-West K. & Sharma D.
British Academy
Physiological Responses to Positive Emotions: Testing the undoing effect.

£1,541

2004

2006

Sharma D. & Brown R.
Economic and Social Research Council
The social regulation of cognitive function

£42,873

2003

2006

Sharma D. 
External collaborator on a French Ministry of Research grant to Huguet P. "Comportement et cognition : Études expérimentales de l'influence du contexte sur le traitement de l'information chez l'homme." ("Behaviour and cognition: Experimental studies of the influence of contextual factors on information processing in humans").
The social regulation of cognitive functioning

£25,000

1996

1997

D Sharma
University of Kent Small grant
Developing an objective measure of sensitivity to alcohol related stimuli.

£1,876

 

Professional Memberships

Member of the Psychonomic Society

University of Kent Centre for Cognitive Neuroscience and Cognitive Systems

School of Psychology
Keynes College
University of Kent
Canterbury, Kent
CT2 7NP
United Kingdom

Tel. +44 (0)1227 823084 
Fax. +44 (0)1227 827030
Email: Dinkar Sharma

Office: Keynes A3.07

Office Hours: Tuesday and Thursday 10-11am

 

School of Psychology - Keynes College, University of Kent, Canterbury, Kent CT2 7NP

Tel: +44 (0)1227 824775; Fax: +44 (0)1227 827030 or Email the School

Last Updated: 19/12/2011