Raised line drawings are spontaneously explored with a single finger.

In this study we examine the strategies used by blindfolded subjects asked to freely explore raised line drawings and identify what is depicted in them. We were particularly interested in how often a single finger is spontaneously used because in several studies subjects are forced to use only one fingertip and the extent to which this restriction may depress haptic perception is unclear. The results suggest that despite a variety of strategies, people 'naturally' use single fingertips sufficiently often to allow confidence in conclusions that are based on studies imposing this restriction.