Integration of length and curvature in haptic perception

We investigated if and how length and curvature information are integrated when an object is explored in one hand. Subjects were asked to explore four types of objects between thumb and index finger. Objects differed in either length, curvature, both length and curvature correlated as in a circle, or anti-correlated. We found that when both length and curvature are present, performance is significantly better than when only one of the two cues is available. Therefore, we conclude that there is integration of length and curvature. Moreover, if the two cues are correlated in a circular cross-section instead of in an anti-correlated way, performance is better than predicted by a combination of two independent cues. We conclude that integration of curvature and length is highly efficient when the cues in the object are combined as in a circle, which is the most common combination of curvature and length in daily life

Haptic adjustment of cylinder radius

Haptic curvature discrimination experiments have typically been done with relatively small stimuli (at most hand-sized) placed on a table. In daily life, however, we often handle large curved objects (think of basket balls), which we usually hold with two hands. Here, I focus on the question how well shape information from the two hands is integrated. I investigated subjects' ability to adjust the distance between two large cylindrical shells in such a way that the two shells together would perceptually form a circular cylinder. All subjects were able to perform this task in a consistent way, but adjustments were often far from veridical. As deviations were often larger than discrimination thresholds, I hypothesize that they are either due to systematic biases in curvature perception or to misestimations of the distance between the hands. These results contribute to our understanding of haptic shape perception

Haptic adjustment of cylinder radius

Haptic curvature discrimination experiments have typically been done with relatively small stimuli (at most hand-sized) placed on a table. In daily life, however, we often handle large curved objects (think of basket balls), which we usually hold with two hands. Here, I focus on the question how well shape information from the two hands is integrated. I investigated subjects' ability to adjust the distance between two large cylindrical shells in such a way that the two shells together would perceptually form a circular cylinder. All subjects were able to perform this task in a consistent way, but adjustments were often far from veridical. As deviations were often larger than discrimination thresholds, I hypothesize that they are either due to systematic biases in curvature perception or to misestimations of the distance between the hands. These results contribute to our understanding of haptic shape perception. Haptic curvature discrimination experiments have typically been done with relatively small stimuli (at most hand-sized) placed on a table. In daily life, however, we often handle large curved objects (think of basket balls), which we usually hold with two hands. Here, I focus on the question how well shape information from the two hands is integrated. I investigated subjects’ ability to adjust the distance between two large cylindrical shells in such a way that the two shells together would perceptually form a circular cylinder. All subjects were able to perform this task in a consistent way, but adjustments were often far from veridical. As deviations were often larger than discrimination thresholds, I hypothesize that they are either due to systematic biases in curvature perception or to misestimations of the distance between the hands. These results contribute to our understanding of haptic shape perception