Haptic Performance in Later Life Figure 3. Development of cognitive performance in later life. A. Individual cognitive performance scores assessed with the RSPM test (i.e., percent correct answers) are depicted for male (blue squares, N = 32) and female (red squares, N = 49) subjects. Trend lines are shown for male (solid blue), female (solid red), and all subjects (dashed black). Cognitive performance declined with increasing age (Pearson correlation, N = 81, r = 20.550, p#0.001). B. Group data for cognitive performance (RSPM score, percentage correct) for younger adults (left squares; female: N = 29, 60.2467.07 years; male: N = 15, 58.5367.62 years) and older adults (right squares; female: N = 20, 76.9565.94 years; male: N = 17, 75.7666.71 years). There was no significant interaction of the subjects’ age and gender with their cognitive performance (AGE*GENDER: F(1,31) = 17.535; p#0.001). Black bars indicate SEM. doi:10.1371/journal.pone.0030420.g003 decline in haptic performance in later life. Instead, intellectual functioning seems to be more predictive than the sensory measure. This finding has strong implications for the view that aging is associated with greater correlations between intellectual status and sensorimotor performance [54,55]. Generally, the influences of healthy aging on haptic performance are hard to reveal as they may vary depending on the experimental set-up that is used (pure haptic or cross-modal testing), the objects used (common or unfamiliar, cubic or natural shape), and other boundary conditions (same/ different or matching task; time constraints). Tactile acuity as a prerequisite for haptics From previous work in older adults, we know that human tactile, haptic, and fine-motor performance decreases as a function of age, but can be restored to some extent by physical intervention programs [70,71], or by focused peripheral stimulation paradigms [44,43,45,72]. Under such conditions, the stimulation-based improvement of tactile acuity was shown to support exploratory procedures in haptic object exploration and object manipulation in fine-motor tests [43,44]. From experiments in healthy adults [73] older adults [38] and patients suffering from impaired tactile perception following central [74] or peripheral neurological disorders [75], it is known that tactile acuity is indispensable for object manipulation, as well as for object recognition. Dellon and Kallman [75] investigated functional sensation in the hands of patients with functional limitations of the median nerve, and found that the moving two-point discrimination test best correlated with the patients’ ability to identify objects using their fingertips. PLoS ONE | www.plosone.org 5 January 2012 | Volume 7 | Issue 1 | e30420