What influences angular acuity in raised line drawings?

Abstract

In this study we investigated the angular resolution subserving the haptic perception of raised line drawings. We found that for acute angles discrimination performance is highly dependent on exploration strategy: mean thresholds of 2.9 and 6.0 were found for two different exploration strategies. For one of the strategies we found that discriminability is not dependent on the bisect orientation of the angle. Furthermore, we found that thresholds almost double when the angular extent is increased from 20 to 135. We also found that local apex information is of significant influence on discrimination for acute as well as obtuse angles. Overall, the results tell us that the acuity with which angles in raised line drawings are perceived is determined by the exploration strategy, local apex information and global angular extent.