Evaluation of pictorial symbols to warn computer keyboard users about carpal tunnel syndrome (CTS)

Carpal tu n nel syndrome (CTS) i s an upper-extremity disorder th a t can cause chron i c pain and disab i lity. Although CTS can arise from a wide variety of repetitive tasks with awkward hand / arm positioning, a large percentage of cases are attributed to, or exacerbated by, computer input devices such as keyboards. One po t ential way to reduce the devel o pment of CTS in keyboard users is to warn them about the disease's early symptoms so that corrective actions might be taken before the disease becomes more severe. The present research systematically examines one of the components of a potential CTS warning, pictorial symbols. Participants examined a set of 12 ANSI Z535 style warnings with one, two or four pictorials. They then evaluated them on their perceived effectiveness, specifically on their ability to inform and motivate users to use correct arm and hand posture to avoid further CTS development. The evaluations involved estimating the percentage of people that would comply with the pictorial message if it were located on or near a keyboard. Individual pictorial symbols in a top or a s i de view of the hands, arms, an d wrists, depicted the incorrect posture overlaid with either an "X" (cross-out) or "prohibition symbol" (circle-slash) or the correct posture with no overlay. Warnings with four pictorials (with both postures and views) were given significantly higher evaluations than warnings with one or two symbols. In the one and two pictorial conditions, the top view was preferred over the side view. The two prohibition symbols, shown together with views of the incorrect postures, were perceived to be better than the views of correct postures (with no prohibition symbol). The two prohibition symbol conditions did not differ. The results could serve as a partial basis for the development of a complete CTS warning that also includes textual information. Implications for the benefits of multi-symbol warning messages are offered.