Use of a Secondary Task Methodology for Determining Acceptability of Flat-Panel Display Technologies in Consumer Environments

Flat-panel displays are used in consumer environments for displaying information where limits on content, physical space, power, and cost constraints are critical. Applications have traditionally included Retail Point-of-Service (POS) terminals. Most common flat-panel display technologies found in the consumer markets are Liquid Crystal Displays (LCDs), Plasma, and Vacuum Fluorescent displays. Emitting displays, i.e., Vacuum Fluorescent, Plasma, and LEDs were introduced into the marketplace with few reservations as to their general acceptance since normal ambient lighting conditions other than direct sunlight had minimal impact on readability. However, reflective display technologies, i.e., LCDs have not been widely accepted in POS products because of slower response times and a more restrictive range of ambient light needed to achieve acceptable viewing conditions. Many techniques used for determining the acceptability of a display technology for the POS environment presently used in industry are solely based upon the physical and functional performance characteristics of the display itself. This approach is similar to those used for evaluating video displays in that the primary concern is the stability of the displayed output for the intended user environment. Often these evaluations are conducted in a laboratory and therefore do not compare display performances relative to the intended end user. Even though this approach is cost-effective because the physical attributes of the display can be tailored to maximize readability, it does not consider the effect of the displayed information beyond the properties of the human visual system. Therefore, it would be desirable to develop an experimental methodology for evaluating flat-panel display technologies based upon human information processing capabilities. This requires using the information in cognitive task loadings equivalent to those experienced in the user environment. Studies comparing LCDs and Plasma display technologies were designed to construct a cognitive-perceptual model for usability assessment in the retail POS environment. A secondary task methodology was used to predict mental workload associated with each display. A Choice Reaction Time (CRT) paradigm proved to be an effective method for exploring cognitive-behavioral problems associated with the displays beyond those considered in the traditional methods of display evaluation.