Age and Haptic Illusion : Apparent Reversal of Movement on the Skin Surface Across the Adult Life Span

The existence of a previously unreported tactile illusion involving the apparent reversal of direction of movement on the skin surface when touching a rotating object was demonstrated. Other pure haptic illusions, as well as tactile illusions representing modifications of known visual illusions, were reviewed and contrasted with this new phenomenon. In addition, this study investigated possible age effects on the perception of this new haptic illusion using twelve female Subjects in each of three age groups (25-39, 40-59, 60+). Both narrow and wide rotating disks were used to see if the amount of skin in contact with the moving surface influenced the reversal illusion. The phenomenon of visual override was investigated by comparing reported haptic reversals with impaired vision and unimpaired vision. For each of the three age groups, the number of reversals for surface widths of the rotating disk for the haptic illusion for each impaired and unimpaired vision trail was recorded (task 1). The study also examined the possible influence of higher order cognitive functioning on the perception if this haptic illusion by relating the number of reported haptic reversal of movement to the number of reported haptic reversal of movement to the number of reversals reported for the Necker Cube illusion for each subject. Finally, each subject completed a questionnaire dealing with measures of cautiousness and risk-taking to determine if the subjective reports of the experiencing of this illusion might have been related to individual’s cautiousness in reporting covertly experience events. The data from the haptic illusion task was analyzed in a series of 3 (age levels) x 2 (narrow vs. wide width) anova designs and Multiple Regression analyses to determine possible age effects, surface width effects and interaction effects. Theses results were related to data dealing with the Necker Cube reversals, visual override effect and cautiousness. The haptic illusion of the apparent reversal of the direction of movement were reported by nineteen of the thirty-six subjects. Age of the subject was not related to the number of haptic reversals, r = .02, nor Necker Cube reversals, r =.16. Regression analysis indicated a weak relationship between Necker Cube and haptic reversals, r =.26, p