Mode preference in a simple data-retrieval task

Mode preference in a simple data-retrieval task Alexander L Rudnicky School of Computer Science, Carnegie Mellon University Pittsburgh, PA 15213 USA ABSTRACT This paper describes some recent experiments that assess user behavior in a multi-modal environment in which actions can be performed with equivalent effect in speech, keyboard or scroller modes. Results indicate that users freely choose speech over other modalities, even when it is less efficient in objective terms, such as time-to-completion or input error. INTRODUCTION Multi-modal systems allow users to both tailor their input style to the task at hand and to use input strate- gies that combine several modes in a single trans- action. As yet no consistent body of knowledge is available for predicting user behavior in multi-modal environments or to guide the design of multi-modal systems. This is particularly true when interfaces in- corporate new technologies such as speech recogni- tion. For activities in a workstation environment, formal comparisons of speech with other input modes have failed to demonstrate a clear advantage for speech on conventional aggregate measures of performance such as time-to-completion [1, 8, 4], despite a con- sistent advantage displayed by speech at the level of single input operations. The difference can actu- ally be attributed to the additional incurred costs of non-real-time recognition and error correction. While real-time performance can he achieved, it is unlikely that error-free recognition will be available in the near future. Given these shortcomings, we might ask if speech can provide advantages to the user along di- mensions other than task speed, for example by re- ducing the effort needed to generate an input. There is reason to believe that users are quite good at estimating the response characteristics of an inter- face and can choose an input strategy that optimizes salient aspects of performance, for example decreas- ing time-to-completion or minimizing task error [5, 9]. By observing the behavior of users in a situation in which they can freely choose between different strate- gies, we can gain insight into the factors that govern their preference for different input styles. A simple data retrieval task was chosen for this study, as the task was one amenable to execution in each of the three modalities that were examined: speech, keyboard and scroller. The database contained in- formation about individuals, such as address, tele- phone, etc selected from a list of conference atten- dees. The task consisted of retrieving the record for an individual and recording the last group of digits in their work telephone number (typically of length four). The database contained 225 names for the first experiment and was expanded to 240 names for the second experiment. SYSTEM IMPLEMENTATION The Personal Information Database (PID) compo- nent of the OM system [3, 7] served as the database system in this study. Given a search request specified in some combination of first name, last name and affil- iation, PID displays a window with the requested in- formation (in this study, the information consisted of name, affiliation and all known telephone …

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