Hand grip strength on a large PDA: holding while reading is different from a functional task

Several studies have been done measuring preferred hand grip strength, but none of them has measured preferred hand strength on a PDA or similar device when it is held and used. We measured dominant hand strength in two conditions similar to real PDA use; resting fore-arms on a table and holding the PDA without table support. We found that adult participants squeeze the device with their preferred hand significantly more than with their nonpreferred hand while holding. In addition, we examined users' hand strength while they were tapping on the back of the device with their right and left index fingers. Our results were different than expected from previous studies, as we found that there was no significant difference in dominant and non dominant hand strength during back tapping. Also participants' non preferred hand strength was not significantly different with their preferred hand when they tap on the back of the device. The results show that in such functional use during tapping, the dominant and non-dominant hands are used similarly which will contribute to future designs for PDAs and their interfaces. Our results may also contribute to design for more comfortable devices for users with hand disabilities