Automatic Bars with Single-Switch Scanning for Target Selection

We present and evaluate two point-select methods using automatic bars or regions and single-switch scanning. The first method, iButton, uses horizontal and vertical bars that move in sequence following switch selections with a final selection at the point of intersection. An additional feature is the scanning of three buttons to set the direction the bars move: left/up, right/down, or none. The second method, CSSS for circular single-switch scanning, rotates a \(\frac{\pi }{8}\) radian arc region, a line within the arc region, and a pointer along the line. Three switch selections are required to select a target. In a Fitts’ law user study with 10 participants, both methods exhibited similar throughput, about 0.35 bps. The iButton method was about 11% faster with selections taking on average 7.80 s compared to 8.74 s with CSSS. However, the CSSS method was about 35% more accurate with a 4.24% error rate compared to a 6.56% error rate with iButton. Eight of ten participants preferred the CSSS method. All participants reported that they felt faster with the CSSS method, even though the iButton method was objectively faster.