RELATIVE AVAILABILITY OF SURFACE AND OBJECT PROPERTIES DURING EARLY HAPTIC PROCESSING

How the relative order in which 4 property classes of haptically perce ived surfaces becomes available for processing after initial contact w as studied. The classes included material, abrupt-surface discontinuit y, relative orientation, and continuous 3-D surface contour properties . Relative accessibility was evaluated by using the slopes of haptic s earch functions obtained with a modified version of A. Treisman's (A. Treisman & S. Gormican, 1988) visual pop-out paradigm; the y(0) interc epts were used to confirm and fine-tune order of accessibility. Target and distracters differed markedly in terms of their value on a single dimension. The results of 15 experiments show that coarse intensive d iscriminations are haptically processed early on. In marked contrast, most spatially encoded dimensions become accessible relatively later, sometimes considerably so.