Biomedical subjects

Susan J Lederman

Publications and source records attributed to Susan J Lederman.

3 recordsLinked to original sources

PubMed2003

Representing spatial location and layout from sparse kinesthetic contacts.

Participants' fingers were guided to 2 locations on a table for 3 s, then back to the start. They reported distances and angles between the locations by (a) replacing 1 or 2 fingers, (b) translating the contacted configuration, or (c) estimating distance or angle alone. Distance error increased across these conditions. Angular error increased when the angular reference axis was rotated before the response. Replacing 1 finger was impaired by a change in posture from exposure to test. The results suggest a kinesthetic representation is used to replace the fingers, but to estimate distance and angle at new locations, a configural representation is computed. This presentation is oriented within an extrinsic reference frame and maintains shape more accurately than scale.

Adult↗

PubMed2002

Using tactile features to help functionally blind individuals denominate banknotes.

This study, which was conducted for the Bank of Canada, assessed the feasibility of presenting a raised texture feature together with a tactile denomination code on the next Canadian banknote series ($5, $10, $20, $50, and $100). Adding information accessible by hand would permit functionally blind individuals to independently denominate banknotes. In Experiment 1, 20 blindfolded, sighted university students denominated a set of 8 alternate tactile feature designs. Across the 8 design series, the proportion of correct responses never fell below .97; the mean response time per banknote ranged from 11.4 to 13.1 s. In Experiment 2, 27 functionally blind participants denominated 4 of the previous 8 candidate sets of banknotes. The proportion of correct responses never fell below .92; the corresponding mean response time per banknote ranged from 11.7 to 13.0 s. The Bank of Canada selected one of the four raised-texture designs for inclusion on its new banknote series. Other potential applications include designing haptic displays for teleoperation and virtual environment systems.

Adult↗

PubMed2002

Face recognition by hand.

We investigated participants' ability to identify and represent faces by hand. In Experiment 1, participants proved surprisingly capable of identifying unfamiliar live human faces using only their sense of touch. To evaluate the contribution of geometric and material information more directly, we biased participants toward encoding faces more in terms of geometric than material properties, by varying the exploration condition. When participants explored the faces both visually and tactually, identification accuracy did not improve relative to touch alone. When participants explored masks of the faces, thereby eliminating material cues, matching accuracy declined substantially relative to tactual identification of live faces. In Experiment 2, we explored intersensory transfer of face information between vision and touch. The findings are discussed in terms of their relevance to haptic object processing and to the face-processing literature in general.

Adolescent↗