Haptic Performance in Later Life Figure 2. Development of tactile performance in later life. A. Individual two-point discrimination thresholds (i.e., inverse tactile acuity) are depicted for male (blue squares, N = 31) and female (red squares, N = 48) subjects. Trend lines are inserted for male (solid blue), female (solid red), and all subjects (dashed black). Tactile acuity declined with increasing age (Pearson correlation, N = 79, r = 0.430, p#0.001). B. Group data for tactile performance (i.e., two-point discrimination threshold) for younger adults (left squares; females: N = 29, 60.2467.07 years; males: N = 15, 58.5367.62 years) and older adults (right squares; females: N = 20, 76.9565.94 years; males: N = 17, 75.7666.71 years). There was no significant interaction of the subjects’ age and gender with their tactile acuity (AGE*GENDER: F(1,31) = 17.535; p#0.001). Black bars indicate SEM. doi:10.1371/journal.pone.0030420.g002 Discussion It has been known for some time that human haptic performance decreases as a function of age [16], but less is known about the neural mechanisms underlying these changes. In a study about haptic performance of adults under conditions were finger movements were restricted, or subjects had to wear gloves, the speed of object identification was more affected than accuracy of identification [46]. In contrast, we have shown recently that the aging process affects both, the speed and the accuracy of haptic identification of unfamiliar objects [44,43] (cf. fig 4a in [44]). In the present study, we investigated age-related changes in haptic performance by combining a haptic task with tests of tactile acuity and of cognitive performance, as the latter abilities are crucial prerequisites for haptic object exploration. Confirming previous findings [45,44,43], we found a significant age-related decline in both tactile and haptic performance. Furthermore, the RSPM test confirmed common knowledge of an age-related decline in cognitive abilities in old age [18,19]. Correlational analyses revealed a strong relationship between individual cognitive and haptic performance, but only relatively minor relationships between individual tactile and haptic performance, as in the present study only data from male subjects reached significance criteria. In female subjects, who generally showed a stronger decline in haptic and cognitive performance, no relationship between tactile acuity and haptic performance was found. Our results indicate that the well- documented loss of tactile acuity in old age [45,67,68,43, 44,37,69,38–41] might not be the primary cause of the age-related PLoS ONE | www.plosone.org 4 January 2012 | Volume 7 | Issue 1 | e30420