Heidi Horstmann Koester

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This study examines how the cognitive and perceptual loads introduced by a word prediction feature impact learning and performance. Two groups of able-bodied subjects transcribed text using two row-column scanning systems for 10 consecutive trials each. The two systems differed only in that one system had a word prediction feature. Subject groups(More)
This paper presents a variety of outcomes data from 24 experienced users of automatic speech recognition (ASR) as a means of computer access. To assess usage and satisfaction, we conducted an in-person survey interview. For those participants who had a choice of computer input methods, 48% reported using ASR for 25% or less of their computer tasks, while(More)
  • H H Koester
  • 2001
The application of speech recognition to the computer access needs of people with disabilities continues to grow, and a greater understanding of user performance with such systems is needed. This article reviews what is known about user performance with speech recognition systems, with a focus on its application to accommodation of physical disability.(More)
We designed and evaluated an agent that recommends a pointing device gain for a given user, with mixed success. 12 participants with physical impairments used the Input Device Agent (IDA), to determine a recommended gain based on their performance over a series of target acquisition trials. IDA recommended a gain other than the Windows default for 9 of 12(More)
Investigators have discovered that the ratio between a user's reaction time and an appropriate scan rate for that user is approximately .65, which we refer to as "the .65 rule." As part of a larger effort to develop software that automatically adapts the configuration of switch access software, data were collected comparing subject performance with a scan(More)
Single-switch scanning is a technique used by some individuals for spoken and/or written communication. We developed a method for adjusting the settings in a single-switch scanning interface to increase a user's text entry rate (TER). We evaluated that method with nine individuals who use single-switch scanning to communicate. Text entry rates improved by(More)
Row-column scanning is a very slow method of communication. Options for increasing text entry rate include 1) dynamically changing the configuration of the row-column matrix or 2) using rate-enhancement techniques like word prediction, but evidence suggests that increased cognitive load imposed by these methods on the user can result in little or no(More)
A keystroke-level model of user performance was developed to predict the improvement in text generation rate with a word prediction system relative to letters-only typing. Two sets of model simulations were tested against the actual performance of able-bodied and spinal cord injured subjects. For Model 1A, user parameter values were determined independently(More)
Performance on automatic speech recognition (ASR) systems for users with physical disabilities varies widely between individuals. The goal of this study was to discover some key factors that account for that variation. Using data from 23 experienced ASR users with physical disabilities, the effect of 20 different independent variables on recognition(More)
PURPOSE We are developing a software system called IDA (Input Device Agent), whose goal is to optimally configure input devices for people with physical impairments. This study assessed IDA's ability to recommend three keyboard parameters in response to measurements of typing performance: repeat rate, repeat delay, and use of StickyKeys. METHOD Twelve(More)