Quantitative overload: a source of stress in data-entry VDT work induced by time pressure and work difficulty.

It is hypothesized that quantitative overload impacts psycho-physiological attributes of data-entry operators, although previous research has focused primarily on different aspects of VDT work, such as working time and environment, work station, keyboards and so forth. The objective of this study was to examine the influence on psycho-physiological responses of time pressure, task demand and their combined effect as underlying causes of quantitative overload while typing. A total of 12 subjects completed four 1-h typing tasks representing two levels of time pressure and task demand. Levels were manipulated by requiring participants to achieve a least number of character strings during each block, and by changing the number of letters in the character strings. Outcomes were measured in subjective assessment of workload, performance-related and physiological measures. Overall, increased time pressure increased perceived workload, productivity rate and heart rate, and decreased initial response time and typing duration. However, increased task demand increased error rate and initial response time with no change in heart rate. Heart rate variability did not indicate increased levels of time pressure or task demand. Quantitative overload as a consequence of time pressure and task demand influenced the subjective and psycho-physiological measures of data-entry operators to some extent.