Redundant visual coding of state information

This paper reviews literature on redundant coding and examines how redundant coding relates to the design of binary-state indicators and controls (widgets) for graphical user interfaces (GUIs). A number of instances of redundant visual information coding are currently utilized in human-computer interface (HCI) design, however their adoption has apparently been driven solely by aesthetic considerations, rather than by human performance considerations. No HCI or related research has been done to examine what effect, if any, redundant coding of GUI widgets has on human performance.;This paper details a series of experiments that were performed to investigate how redundant coding mechanisms and their combinations may affect the usability of (i.e., aspects of human performance issue related to) common GUI software controls. The aim of these studies was three-fold (1) to determine whether or not redundant coding would facilitate performance, (2) to differentiate the degree to which performance would be enhanced through the use of various visual features that provide the redundant coding, and (3) to determine whether or not user preferences would align with their performance. In each case it was hypothesized that the redundant information coding, ostensibly used to enhance performance, would indeed do so.;Moreover, it was hypothesized that combinations of redundant coding (i.e., multiple redundancies) would lead to better performance than unitary redundant coding (in at least an additive relationship, if not a multiplicative one). The studies used binary-state soft controls/indicators (GUI widgets) similar to those in common use in human-computer graphical user interfaces.;The results indicated that the redundancy features used in these investigations did affect both performance and preference for binary-state GUI widgets. However the impact of each feature was not the same across the identification, search, and preference tasks and in several cases multiple features led to better performance than unitary features. Based on these results, design considerations for binary-state GUI widgets are discussed.