Discrimination Capabilities of Professionals in Manual Skills in a Haptic Task Not Related to Their Expertise

In this study we present a comparative research between the discrimination capabilities of two populations: Professionals in manual skills and non-professionals, in a task that was not related to their field of expertise. The task was, in a psychophysical test, to discriminate between surfaces of different roughness by indirect touch, using a 3D hapto-visual virtual reality (VR) device. In a texture-difference recognition test subjects glided a pen-like stylus on a virtual surface. The surface was divided into five areas: one central, and four surrounding areas. The roughness of the central area was kept constant throughout the experiment. In each run, three of the four surrounding areas were kept at the same roughness as the central surface, and one, randomly, was different. From run to run, surface roughness was changed following a binary search paradigm. If a subject recognized the portion of the surface with a different roughness, then the roughness was reduced by half; if not, the roughness increased, and so on, until the desired degree of accuracy was achieved. Five professionals from different haptic expertise fields and five non professionals participated in the experiment. The results of the study showed that laymen were significantly more sensitive than experts on roughness discrimination (p < 0.01). These results may suggest that intensive manual activity that demands particular haptic expertise may have a negative impact on manual tasks that are irrelevant to their daily professional activity.