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5. STRESS AND PERFORMANCE
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5.1 Effects of Noise on Performance (Baddeley, Edwards, Forster, Poulton)
Work in this area has primarily been concerned with further discussion of Foulton's theory that noise affects performance by sasking the sounds of the response equipment and of inner speech 86; 187; 188; 189; 192; 196), together with a further discussion of Forster and Grierson's failure to observe attentional selectivity in noise. This aspect of the project has now been completed.
A second line of investigation has been carried out by Dr. P. Salame (visiting the A.P.U. from the C.N.R.S. Strasbourg) and Baddeley on the observation that short-term memory for visually presented material may be disrupted by unattended speech. Results so far have shown chat the disruption effect does not depend upon the meaningful-ness of the speech or its synchronisation with the material to be recalled. Disruption does not occur with tasks involving reading or rhyme judgments, suggesting a specific memory decrement racher than a general attentional effect. We plan to explore the generality of Che effect further and attempt to identify its location within working memory. This should allow an evaluation of the usefulness of the technique as a theoretical tool for analysing memory together with its likely practical significance within the working environment (208 U).
5.2 Anxiety and performance (Baddeley, Idzikowski)
While there is abundant anecdotal evidence that fear may impair performance, there is surprisingly little good empirical evidence on this point (113). The project has attempted to collect evidence from two stressful environments, public speaking and sport parachuting. In both cases subjective state was measured using questionnaires, and physiological arousal was monitored by means of electrocardiography using small portable (Medilog) recorders. Cognitive performance was tested shortly before the critical event. Both situations generated considerable anxiety as evidenced by both subjective responses and heart rate. In general performance effects have been small, with only digit span and verbal fluency showing significant impairment. Unfortunately, however, for practical and ethical reasons it did not prove possible to test subjects at Cheir point of maximum anxiety. It is hoped, using Array trainee parachutists, to repeat these studies with the test given closer in time to the actual jump. Meanwhile, Che pattern of anxiety during the week preceding the jump and during the jump itself is providing valuable information on coping behaviour of both novice and experienced parachutists. Since we have personality tests on the jumpers, we should also be able to study the relationship between temperament and mode of coping with a fearful situation.
5.3 Diving research (Baddeley, Godden, Lewis, Logie)
In addition to concluding our work on the role of the underwater context in memory (89; 91) we took part in a Department of Employment funded project on the selection of trainee divers. This was carried out jointly with the university of Stirling: the Unit's concern has focussed on an analysis, based on divers' logs and interviews, of the job of a North Sea diver (90). This provides a much-needed background for studies of diver performance under more controlled laboratory conditions. Our own work in this area has been in collaboration with the A.M.T.E. Physiological Laboratory at Gosport, where divers have been exposed in a dry pressure chamber to conditions equivalent to a depth of between one and two thousand feet of sea water. Our role in these trials has been to monitor the divers' performance. We detected a decrement in several tasks at pressures exceeding one thousand feet of sea water. Data from sleep diaries and subjective ratings of alertness and anxiety suggest that the decrement is probably due to the oxy-hclium breathing mixture, and is not a secondary effect of fear or sleep loss (118). This work is continuing using Tri-mix, a helium-nitrogen-oxygen mixture which has been claimed to reduce the narcotic effects of oxy-helium. In the one dive so far studied this claim was clearly not supported: very marked performance decrements were found (22 U). We plan to continue to collaborate with A.M.T.E./P.L. on this project.
5.4 Psychological wellbeing of telephone switchboard operators (Brown, Wastell, Wilson, Copeman)
Operational research within British Telecom (formerly the Post Office) and earlier A.P.U. studies (52) indicated that trends in telephone switchroom design were having an adverse effect on the attitudes and productivity of operators. This evidence was supported by an M.R.C, funded study (262) of the social factors determining operators' attitudes towards their job. A subsequent psychophysiological field study of individual task performance (53) established that operators of modern 'cordless' switchboards were less productive and less responsive to diurnal fluctuations in call-traffic load than operators of the earlier 'cord' boards but that no differential stress effects were exhibited on the physiological indices measured.
A factor analytic study of operators' self-rated mood throughout their working day revealed that a factor termed 'well-being' was associated with this measured difference in performance, although a second self rated factor, termed 'competence', was not (230).
A further field study, now nearing completion, was conducted to establish where, in their call-handling procedures, cord board operators are able to achieve their greater efficiency. Discussions are in progress with the Human Factors Division of the British Telecom regarding collaborative research designed to validate the remedial measures suggested by these A.P.U. studies. Any results should have a general application to a wide variety of queue-serving tasks where technological developments, introduced on cost criteria, threaten the quality of service provided to the general public.