title: Delays and user performance in human-computer-network interaction tasks.
abstract: OBJECTIVE
  This article describes a series of studies conducted to examine factors affecting user perceptions, responses, and tolerance for network-based computer delays affecting distributed human-computer-network interaction (HCNI) tasks.
  
  
  BACKGROUND
  HCNI tasks, even with increasing computing and network bandwidth capabilities, are still affected by human perceptions of delay and appropriate waiting times for information flow latencies.
  
  
  METHODS
  Conducted were 6 laboratory studies with university participants in China (Preliminary Experiments 1 through 3) and the United States (Experiments 4 through 6) to examine users' perceptions of elapsed time, effect of perceived network task performance partners on delay tolerance, and expectations of appropriate delays based on task, situation, and network conditions.
  
  
  RESULTS
  Results across the six experiments indicate that users' delay tolerance and estimated delay were affected by multiple task and expectation factors, including task complexity and importance, situation urgency and time availability, file size, and network bandwidth capacity. Results also suggest a range of user strategies for incorporating delay tolerance in task planning and performance.
  
  
  CONCLUSIONS
  HCNI user experience is influenced by combinations of task requirements, constraints, and understandings of system performance; tolerance is a nonlinear function of time constraint ratios or decay.
  
  
  CONCLUSIONS
  Appropriate user interface tools providing delay feedback information can help modify user expectations and delay tolerance. These tools are especially valuable when delay conditions exceed a few seconds or when task constraints and system demands are high. Interface designs for HCNI tasks should consider assistant-style presentations of delay feedback, information freshness, and network characteristics. Assistants should also gather awareness of user time constraints.
authors.affiliation: School of Industrial Engineering, Purdue University, 315 N Grant St., #228D, West Lafayette, IN 47907-2023, USA. bscaldwell@purdue.edu
authors.forename: Barrett S
authors.initials: BS
authors.lastname: Caldwell
authors.forename: Enlie
authors.initials: E
authors.lastname: Wang
mesh_terms: D001292:Attitude to Computers; D002681:China; D003195:Computer Communication Networks; D003258:Consumer Behavior; D006804:Ergonomics; D005246:Feedback; D005260:Female; D006801:Humans; D008297:Male; D015146:Midwestern United States; D015999:Multivariate Analysis; D013998:Time Perception; D014584:User-Computer Interface