title: Interactive model of subsidiary behaviors, work performance and autonomic nerve activity during visual display terminal work.
abstract: OBJECTIVE
  The aims of the study were to investigate the systematic classification of subsidiary behaviors during visual display terminal (VDT) work and discuss the interpretation of these behaviors through an interactive model of subsidiary behaviors, work performance and autonomic nerve activity.
  
  
  METHODS
  Twelve university students were instructed to perform continuous 120-min English transcription tasks in a sedentary posture. Data on subsidiary behaviors, work performance (mean keystroke and mean error rates), and autonomic nervous system balance (log-transformed low frequency (LF) / high frequency (HF) ratio) were recorded every 5 min during VDT work.
  
  
  RESULTS
  The subsidiary behaviors were categorized into 3 qualitatively independent factors: distractive behaviors against monotony (DBM), sleepiness-related behaviors (SRB), and habitual behaviors (HB). A cross-correlation analysis indicated that an increase of DBM, which is considered as a sign of workers' attempt to escape from monotonous task operations, was related to a decline in performance. A decrease in the LF/HF ratio was followed by SRB after 5 min passed (r=-0.57, p<0.05), eventually leading to a restriction of the deterioration in performance. An increase of DBM was predictive of an increase in errors (r=0.54, p<0.05), and a significant negative correlation (r=-0.46, p<0.05) between HB and autonomic nerve activity at 10 min after the appearance of HB was observed.
  
  
  CONCLUSIONS
  It emerged from the results that the factor structure of subsidiary behaviors consists of 3 mutually independent factors. The interactive model suggests that subsidiary behaviors are possibly precursory signs of errors and changes in autonomic nervous system balance.
authors.affiliation: Department of Occupational and Environmental Health, Nagoya City University Graduate School of Medical Science, Japan.
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Takanishi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ebara
authors.forename: Gen-i
authors.initials: GI
authors.lastname: Murasaki
authors.forename: Tomohide
authors.initials: T
authors.lastname: Kubo
authors.forename: Norihide
authors.initials: N
authors.lastname: Tachi
authors.forename: Toru
authors.initials: T
authors.lastname: Itani
authors.forename: Michihiro
authors.initials: M
authors.lastname: Kamijima
mesh_terms: D017776:Autonomic Pathways; D006804:Ergonomics; D005221:Fatigue; D005260:Female; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D009043:Motor Activity; D013647:Task Performance and Analysis; D014495:Universities; D014584:User-Computer Interface; D055815:Young Adult