PURPOSE: For individuals with severe motor and communicative disabilities, single switch scanning provides a way to access a computer and communicate. A model was developed that utilizes scanning interface settings, error tendencies, error correction strategies, and the matrix configuration to predict a user's communication rate. METHOD: Five individuals who use single switch scanning transcribed sentences using an on-screen keyboard configured with the settings from their communication devices. Data from these trials were used as input to a model that predicted TER for the baseline configuration and at least three other system configurations. Participants transcribed text with each of these new configurations and the predicted TER was compared to the actual TER. RESULTS: Results showed that predicted TER was accurate to within 90% on average. The scan rate was also entered into a previously published model which assumes error-free performance. For our model, the average error for each participant was 10.49%, compared to 79.7% for the model assuming error-free performance. CONCLUSIONS: Our model of row-column scanning was much more accurate than a model that did not consider the likelihood of an error occurring. There is still room for improvement, however, and the results of the study will lead to additional modifications of the model.
PURPOSE: For individuals with severe motor and communicative disabilities, single switch scanning provides a way to access a computer and communicate. A model was developed that utilizes scanning interface settings, error tendencies, error correction strategies, and the matrix configuration to predict a user's communication rate. METHOD: Five individuals who use single switch scanning transcribed sentences using an on-screen keyboard configured with the settings from their communication devices. Data from these trials were used as input to a model that predicted TER for the baseline configuration and at least three other system configurations. Participants transcribed text with each of these new configurations and the predicted TER was compared to the actual TER. RESULTS: Results showed that predicted TER was accurate to within 90% on average. The scan rate was also entered into a previously published model which assumes error-free performance. For our model, the average error for each participant was 10.49%, compared to 79.7% for the model assuming error-free performance. CONCLUSIONS: Our model of row-column scanning was much more accurate than a model that did not consider the likelihood of an error occurring. There is still room for improvement, however, and the results of the study will lead to additional modifications of the model.