The Development of an Objective Indicator of Occupational Stress using the Emotional Stroop Paradigm

Reeves, Elaine (2017) The Development of an Objective Indicator of Occupational Stress using the Emotional Stroop Paradigm. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

In 2015-16, work-related stress, anxiety and depression accounted for approximately 11.7 million working days lost to ill health, explaining 37% of all work-related cases of ill health in the UK and defining the need for organisational risk assessment. However, it is widely acknowledged that current methods used in risk assessments to identify and evaluate occupational stress and its’ consequences have considerable limitations. This thesis was concerned with the consideration and evaluation of occupational stress and contemporary measures of occupational stress prior to the construction and piloting of an occupational stress- related Stroop task as an objective indicator of occupational stress in different occupational settings. Previous research has demonstrated robust emotional Stroop interference for colour naming of threat-related stimuli by anxious individuals. Cognitive theories of emotion and attention offer various underlying explanations for why this happens but generally agree that anxiety and similarly stress, elicit an automatic, attentional bias towards threatening stimuli in emotional Stroop tasks. Therefore, it is predicted that the colour naming performance of participants (across a range of different occupations) higher in occupational stress will be inhibited by occupational stress-related words in an emotional Stroop task. Study One was primarily concerned with the construction of appropriate word sets for an occupational stress-related Stroop task. Data from interviews (N = 10), a focus group (N = 7) and self-report occupational stress scales (N = 4) were content analysed to provide a set of 20 relevant occupational stress-related words. Neutral, social threat and physical threat control word sets were also constructed and all stimuli were balanced for lexical characteristics known to affect colour naming times, with a particular focus on word frequency using a British-English frequency list rather than the routinely used American lists. The final occupational stress-related Stroop task contained 80 words for computer presentation in a single word, semi-random sequence, once in each of four colours. Study Two employed the occupational stress-related Stroop task to elicit attentional bias in white-collar workers (N = 80) who were chosen as fairly representative of a substantial proportion of the workforce in the UK. Participants were divided into high (n = 18) and low stress (n = 17) groups based on sources of pressure scores from an established work stress questionnaire which followed completion of the emotional Stroop task. Analysis of colour naming latencies revealed significantly slower times in the high stress group for occupational stress words compared to neutral words supporting Hypothesis One and also in contrast to the low stress group in accordance with Hypothesis Two. Study Three tested the utility of the occupational stress-related Stroop with an opportunity sample of Further Education teachers (N = 15) using the same method as in Study Two to test the extended utility of the task to a different occupational group who might report different psychosocial factors associated with their job role. Teachers are reported to have higher levels of perceived stress and consequent strain than the average working person so it was reasonable to assume they would exhibit attentional bias towards occupational stress-related stimuli. Analysis of colour- naming latencies showed that the high stress group (n = 15) were significantly slower for occupational stress-related words than neutral supporting Hypothesis One, and when compared to the low stress group (n = 13) lending support to Hypothesis Two. The high stress group also had significantly slower response times for physical threat-related words in comparison to neutral which was discussed as an unexpected finding. Study Four extended the use of the occupational stress-related Stroop to a sample of police firearms officers (N = 52) to investigate whether the generic occupational stress-related stimuli elicited attentional bias towards occupational stress-related words in higher stress participants. Analysis of colour naming times indicated significantly slower responses in the high stress group only (n = 13) for occupational stress words in comparison to neutral words (and in comparison to other threat words). These findings supported Hypotheses One. No significant differences were observed for interference scores between occupational stress and neutral or for any other word types when comparing the high and low stress (n = 13) group. This was contrary to Hypothesis Two and possible explanations for this anomaly were discussed. These results taken together suggest that the occupational stress-related Stroop task constructed for this doctoral research was relatively successful as an objective indicator of occupational stress across three different occupational groups as the higher stress participants took significantly longer to colour-name occupational stress-related words in comparison to neutral in Study Two, Three and Four demonstrating Stroop interference within each of the high stress groups (white-collar workers, teachers and firearms officers) towards occupational stress-related words. The findings are less conclusive in terms of significant differences in Stroop interference towards occupational stress-related words between the high and low stress groups as although significantly longer interference scores for occupational stress words were found for white-collar workers, this was not the case for firearms officers. Whilst significantly more interference for occupational stress words was found for teachers, they also exhibited significant interference from physical threat words. Possible reasons for this were discussed. The stronger findings for analysing colour-naming latencies (within-groups differences) in comparison to analysing interference scores (between-subjects) is however in line with numerous other emotional Stroop tasks and has been blamed on issues with test-retest reliability which requires further consideration. The occupational stress-related Stroop task requires further piloting in conjunction with established measurement methods such as self-report or physiological indicators in organisational risk assessment to determine its potential as a reliable stress measurement tool across occupational settings.