A comparison of tactile and blurred visual form perception

Two experiments were performed to assess the similarity of tactile form perception and visual form perception under conditions of extreme visual blurring. In the first experiment, resolution and relative localization tasks were performed by five subjects under both tactile and blurred visual presentation. The results obtained here were the same for the two modalities. In the second experiment, all 26 block letters were presented to each of four subjects in two distinct methods of presentation, using both tactile and blurred visual displays. In one method, the full-field letter was flashed for 1.0 sec; in the other, a vertical slit scanned the letter from left to right. For all method comparisons, a strong similarity was found between the patterns of correct responses as a function of letter. In addition, there was a definite similarity between the two modalities in terms of which letters improved in recognizability in the change from the full-field to the slit mode of presentation. However, the overall superiority of the slit method found for tactile recognition was not obtained visually. The two experiments indicate that recognition with blurred vision is similar to recognition using the intact cutaneous sense, although some differences remain.     

Length distortion of temporally extended visual displays: similarity to haptic spatial perception

Three experiments were designed to investigate length distortion--the tendency to inflate estimates of the inferred distance between two points, as the length of a circuitous pathway between them increases. This phenomenon, previously demonstrated with haptic and locomotor exploration (Lederman, Klatzky, Collins, & Wardell, 1987), was extended to vision through the presentation of pathways as a temporal sequence of illuminated points. The magnitude of the visual effect was less than that previously found in haptics, and conditions promoting the effect included a relatively slow presentation rate and moderately complex pathways. Commonalities in the pattern, if not the magnitude, of length distortion in vision and haptics suggest that similar processes of spatial encoding may underlie the phenomenon in both domains.     

The role of vibration in the tactual perception of roughness

Katz (1925) has argued that the sense of vibration underlies the tactual perception of roughness. However, Taylor and Lederman (1975) have suggested that vibration serves only to prevent the cessation of mechanoreceptor activity. In an experimental evaluation of these positions, it is shown that, although prior (selective) adaptation of the fingertip strongly affects the perceived magnitude of supraliminal vibrotactile signals, it fails to alter the perceived roughness of metal gratings. The results thus favor the Taylor and Lederman position. The paper also speculates on roughness coding by the mechanoreceptor populations present in glabrous skin of the human hand.     

Does energy expenditure affect the perception of egocentric distance? A failure to replicate experiment 1 of Proffitt, Stefanucci, Banton, and Epstein (2003)

In a series of recent studies, Proffitt and his colleagues have reported that the perceived distance to a target is influenced by the energy expenditure associated with any action, such as walking or throwing, for spanning the distance to the target. In particular, Proffitt, Stefanucci, Banton, and Epstein (2003) reported that wearing a heavy backpack caused verbal reports of distance to increase. We conducted a study to determine whether three responses dependent on perceived distance (verbal report of distance, blind walking, and estimates of object size) are influenced by the backpack manipulation. In two experiments, one involving a between-participants design and the other involving a within-participants design, we found that none of the three responses were influenced by the wearing of a heavy backpack.