Lag as a Determinant of Human Performance in Iteractive Systems
The sources of lag (the delay between input action and output response) and its effects on human performance are discussed. We measured the effects in a study of target acquisition using the classic Fitts' law paradigm with the addition of four lag conditions. At the highest lag tested (225 ms), movement times and error rates increased by 64% and 214% respectively, compared to the zero lag condition. We propose a model according to which lag should have a multiplicative effect on Fitts' index of difficulty. The model accounts for 94% of the variance and is better than alternative models which propose only an additive effect for lag. The implications for the design of virtual reality systems are discussed.
Journal or Conference Title
Conference on Human Factors in Computing Systems (CHI)
Proceedings of the INTERACT '93 and CHI '93 conference on Human factors in computing systems
Apr 24 - Apr 29, 1993
New York, NY. USA
Association for Computing Machinery (ACM)
Digital Object Identifier (DOI)
I. S. MacKenzie and C. Ware, "Lag as a determinant of human performance in interactive systems," in Proceedings of the SIGCHI conference on Human factors in computing systems - CHI ’93, Association for Computing Machinery (ACM), 1993.