An Initial Investigation of Factors Affecting Multi-Task Performance

Report No. ARL-TR-4025
Authors: Teresa A. Branscome;Jennifer C. Swoboda;Linda T. Fatkin
Date/Pages: February 2007; 48 pages
Abstract: This report presents the results of the first in a series of investigations designed to increase fundamental knowledge and understanding of the factors affecting multi-task performance in a military environment. The primary objective of this laboratory experiment was to measure and quantify the effects of individual differences on human performance in a multi-task environment. The secondary objective was to observe the effects of previous computer experience and practice and to determine which relationships, if any, exist between personality and self-efficacy traits and multi-task performance. In this study, each of 76 civilian and military participants completed a battery of questionnaires designed to gather information about individual differences. Included were a demographics questionnaire that solicited information regarding age, gender, vision and hearing, military service, and computer use and experience; the Zuckerman-Kuhlman Personality Questionnaire Form III which identifies five components of personality in five subscales including activity, aggression-hostility, sociability, neuroticism-anxiety, and impulsive risktaking; the polychronicity scale which measures the extent to which individuals prefer working on several tasks at once as opposed to working on only one task at a time; and the Situational Self-Efficacy (SSE) scale which measures the participants? level of confidence in their ability to do a task well. After completion of the questionnaires, multi-task performance was measured using SYNWORK (Synthetic Work Environment), a computer-based synthetic work environment that runs on a personal computer or a laptop (Elsmore, 1994). Participants were required to work simultaneously on four distinct tasks that were presented on a computer screen: Sternberg memory, three-column addition, visual tracking, and signal discrimination. These tasks required continuous attention and involved memory, arithmetic processing, and visual and auditory monitoring. Pearson correlation coefficients were computed to determine relationships between questionnaire responses and SYNWORK scores. Overall SYNWORK scores showed a significant negative correlation with age group, neuroticism, and impulsivity, and a significant positive correlation with trial. In addition, significant positive correlations existed between total SYNWORK scores and components of the polychronicity scale. Results indicated that participants who preferred working on several projects at a time scored higher overall on the SYNWORK task. Multivariate analyses conducted on individual and overall task performance measures indicated a significant interaction between age group and trial. Consistent with our expectations, it was found that initially, younger adults performed better on multi-task performance, but all age groups improved performance with practice. Multiple regression analyses were conducted on overall task performance measures. The variable that is consistently retained at the end of the stepwise regression analyses is the N-Anxiety subscale of the personality questionnaire. Those less prone to emotional upsets or worrying performed better at multi-task monitoring than people who were more reactive and sensitive to criticism. When age, education level, and neuroticism were included in the model, 32.5% of the variance was explained. Cluster analysis was used to examine the effect of individual differences on the performance outcome. An analysis of the SSE variable revealed two distinct groups of individuals with high and low levels of confidence in their ability to do well. Post hoc analyses indicated that people who reported high SSE performed significantly better at multitask monitoring than those who reported lower SSE level.
Distribution: Approved for public release
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Last Update / Reviewed: February 1, 2007