An examination of direct selection typing rate and accuracy for persons with high-level spinal cord injury using QWERTY and default on-screen keyboards.

A single-subject rapid alternating treatment design with replication was used to compare the efficiency of two keyboard layouts, QWERTY and default, for persons with high-level spinal cord injury. The LIAISON system and proportional-drive chin controller provided computer access/writing to four subjects. Three efficiency characteristics were examined: keystrokes per minute, keystroke accuracy, and keystroke corrections. Baseline sessions were followed by 10 to 12 alternating treatment sessions for all subjects. Each alternating treatment session involved six text entry trials--three text entry trials using the QWERTY keyboard layout and three using the default keyboard layout. Four follow-up sessions were completed for each subject using the default keyboard configuration. Data analysis revealed that the default keyboard layout provided greater keystrokes per minute for two of the subjects. The keystroke accuracy was between 98% and 100% for all subjects on both keyboard layouts. The findings of this investigation revealed no clinically significant difference in typing performance across the two keyboard layouts for the participating subjects. The results also indicate that previous experience with a keyboard configuration is an important factor in determining performance. A possible treatment interaction or carryover effect between the two keyboard configurations was noted and has implications for the type of single-subject design used in future investigations.