Experience-dependent visual cue integration based on consistencies betweenvisual and haptic percepts

We study the hypothesis that observers can use haptic percepts as a standar d against which the relative reliabilities of visual cues can be judged, an d that these reliabilities determine how observers combine depth informatio n provided by these cues. Using a novel visuo-haptic virtual reality enviro nment, subjects viewed and grasped virtual objects. In Experiment 1. subjec ts were trained under motion relevant conditions, during which haptic and v isual motion cues were consistent whereas haptic and visual texture cues we re uncorrelated, and texture relevant conditions, during which haptic and t exture cues were consistent whereas haptic and motion cues were uncorrelate d. Subjects relied more on the motion cue after motion relevant training th an after texture relevant training, and more on the texture cue after textu re relevant training than after motion relevant training. Experiment 2 stud ied whether or not subjects could adapt their visual cue combination strate gies in a context-dependent manner based on context-de pendent consistencie s between haptic and visual cues. Subjects successfully learned two cue com bination strategies in parallel, and correctly applied each strategy in its appropriate context. Experiment 3, which was similar to Experiment except that it used a more naturalistic experimental task, yielded the same patter n of results as Experiment 1 indicating that the findings do not depend on the precise nature of the experimental task. Overall, the results suggest t hat observers can involuntarily compare visual and haptic percepts in order to evaluate the relative reliabilities of visual cues, and that these reli abilities determine how cues are combined during three-dimensional visual p erception. (C) 2001 Elsevier Science Ltd. All rights reserved.