TY - JOUR T1 - Fast and accurate edge orientation processing during object manipulation JF - bioRxiv DO - 10.1101/163790 SP - 163790 AU - J. Andrew Pruszynski AU - J. Randall Flanagan AU - Roland S. Johansson Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/07/15/163790.abstract N2 - From buttoning a shirt to fastening a jewellery clasp, quickly and accurately extracting fine information about a touched object’s orientation is a critical aspect of dextrous object manipulation. However, the speed and acuity of tactile edge orientation processing as reported in previous perceptual studies appear inadequate in these respects. Here, for the first time, we directly establish the capacity of tactile edge orientation processing during object manipulation. With vision occluded, participants placed their fingertip on the surface of a dial and rotated it to position a pointer, extending from the dial, to a fixed target position. The contacted surface was flat except for a small raised edge in line with the pointer. The length of the edge and the initial orientation of the dial were varied across trials. Participants extracted tactile information about edge orientation very quickly, initiating appropriate rotation within ∼200 ms of first touching the dial. Participants were also strikingly accurate. With edges spanning the entire contact area of the fingertip, their average pointer-alignment error was less than 3°, indicating tactile edge-orientation resolution many times better than previously reported. Performance did not improve substantially when the person could see the pointer and remained impressive even with edges as short as 2 mm, consistent with our ability to precisely manipulate very small objects. Taken together, our results radically redefine the spatial processing capacity of the tactile system. ER -