Attunement, calibration, and exploration in fast haptic perceptual learning.

Often, a relatively small number of trials suffices to enhance one's task-specific perceptual capability. In the present experiment, fast perceptual learning was investigated with respect to the perception of the heights or widths of wielded nonvisible rectangular objects. In that haptic perceptual task, inertial differences (mass and moments of inertia) are the basis for perceived size differences. The authors hypothesized that rapid improvement might occur in attunement (attending to the task-relevant inertial variable), calibration (scaling spatial extent to the task-relevant inertial variable), and exploratory behavior (wielding so as to differentiate the task-relevant inertial variable). Twenty-four students performed 25 trials with a set of practice objects; those trials were followed and preceded by 18 trials with a set of test objects. Practice, with knowledge of results (KR), improved both attunement, as measured by regression of perceived spatial extent on the inertial variables, and calibration, as measured by constant and variable error. Of the preceding measures, only variable error improved with practice in the absence of KR. In both KR conditions, however, exploratory behavior decreased in duration and complexity, as measured by recurrence quantification analysis. The present results suggest that the mechanisms involved in fast perceptual learning are more varied and complex than are those encompassed by current accounts.