Wiard Jorritsma

This study aimed to determine the most appropriate touch-based interaction technique for I2Vote, an image-based audience response system for radiology education in which users need to accurately mark a target on a medical image. Four plausible techniques were identified: land-on, take-off, zoom-pointing, and shift. The techniques were implemented in such a way that they could be used on any modern device. An empirical study was performed in which users marked a target on an image using all four techniques on either a smartphone or a tablet. The techniques were compared in terms of accuracy, efficiency, ease of use, intuitiveness, and compatibility with the different devices. The results showed that shift was the most accurate technique, but it was hampered by its high complexity and low intuitiveness. Land-on was the fastest technique but also the least accurate. Take-off and zoom-pointing provided the best trade-off between accuracy, efficiency, ease of use, and intuitiveness. We therefore conclude that both take-off and zoom-pointing are viable interaction techniques for I2Vote.