Perceptions of control over work: psychophysiological responses to self-paced and externally-paced tasks in an adult population sample.

This experiment tested the hypothesis that perceptions of control over work pace would modulate cardiovascular reactions to mental stress tests. One hundred and thirty two adults aged 30-65 years (64 men and 68 women) were randomized to self-paced and externally-paced task conditions. The self-paced group carried out visual matrix problem solving and mirror tracing tasks at their own pace. Work pace requirements were imposed on the externally-paced group, with performance requirements being set to equate those in the self-paced condition. This was done to equate work demands. Blood pressure (assessed with the Finapres), heart rate, cardiac baroreceptor reflex sensitivity, skin conductance, respiration rate and tidal volume were monitored. Behavioural performance of the mirror tracing task was comparable in the two conditions, but the externally-paced group attempted more problems and made more errors on the visual matrix task. Systolic blood pressure reactions to mirror drawing were greater in the external than self-paced conditions (mean increases of 27.5 +/- 16.1 vs. 23.1 +/- 18.5 mmHg, P < 0.025), and electrodermal responsivity was also heightened in the externally-paced group (P < 0.05). No differences were recorded in diastolic blood pressure, heart rate, baroreflex sensitivity or respiratory parameters. Results are discussed in relation to the literature on control and physiological stress responsivity, and their implications for understanding the health consequences of lack of control at work are considered.