Hiromi Wake

Haptic identification of objects and their depictions

Haptic identification of real objects is superior to that of raised two-dimensional (2-D) depictions. Three explanations of real-object superiority were investigated: contribution of material information, contribution of 3-D shape and size, and greater potential for integration across the fingers. In Experiment 1, subjects, while wearing gloves that gently attenuated material information, haptically identified real objects that provided reduced cues to compliance, mass, and part motion. The gloves permitted exploration with free hand movement, a single outstretched finger, or five outstretched fingers. Performance decreased over these three conditions but was superior to identification of pictures of the same objects in all cases, indicating the contribution of 3-D structure and integration across the fingers. Picture performance was also better with five fingers than with one. In Experiment 2, the subjects wore open-fingered gloves, which provided them with material information. Consequently, the effect of type of exploration was substantially reduced but not eliminated. Material compensates somewhat for limited access to object structure but is not the primary basis for haptic object identification.

Attentional Bias to Direct Gaze in a Dot-Probe Paradigm

Previous research has suggested that a singly presented facial stimulus having a direct gaze holds spatial attention. This study examined whether facial stimulus having a direct gaze can also capture spatial attention in a relative dot-probe paradigm (facial stimulus having a direct gaze was presented concurrently with that having an averted gaze). The results showed that participants oriented their spatial attention to a facial stimulus having a direct gaze rather than to that with an averted gaze. This attentional bias depended on gaze-perception mechanisms as observed in the lack of attentional bias to a direct gaze from unnatural-looking eyes (i.e., white pupil/iris and black sclera). These findings raise the possibility that the attentional effect implicated in the perception of a direct gaze is induced regardless of the stimulus context.

The effect of frequency upon tactile apparent movement

Tactile apparent movement was observed under the conditions of variation in stimulus duration, frequency, and separation between two stimuli. First, optimal stimulus onset asynchrony (SOA) was determined as a function of stimulus duration using stimuli with the same frequency. Second, optimal SOA was estimated as a function of frequency, by using two stimuli with different frequencies. The optimal SOA for tactile apparent movement increased with the increases of stimulus duration. When two vibrators activate with the same frequency, the optimal SOA depends on frequency. The optimal SOA of the low‐frequency stimulus (10 Hz) is longer than that of the high‐frequency stimulus (250 Hz). If the first stimulus is 10 Hz and the second stimulus is 200 Hz, the optimal SOA is shorter than two stimuli with same frequency (10 Hz). The first stimulus was kept constant at 10 Hz and the second stimulus was varied in frequency. As the frequency‐difference increases, the optimal SOA is decreased, but at the second stimulu...

Rotating Goblet and Talking Profiles: Does a Rotating Goblet Increase the Figural Dominance of Profiles in Rubin's Type of Figure-Ground Reversal Patterns?

We present a novel three-dimensional (3-D) version of Rubins classical bistable goblet–profiles figure. An actual goblet sculpture was produced and rotated on a turntable in front of a white background. As the goblet rotates about its central axis, small circular asymmetries around the lips and chin region give a clear impression of two white profiles talking to each other. Although the profiles actually correspond to empty space or white background, they are more likely to be perceived as ‘figure’ than the 3-D goblet itself. Four experiments that presented the actual goblet (experiment 1) or two-dimensional (2-D) movies of it (experiments 2–4) were designed to verify these observations. We measured perceptual dominance of profiles as ‘figure’ and rate of reversal as a function of three factors: Motion (static vs rotating), orientation (upright vs inverted), and configuration (face-to-face vs back-to-back). Results for the rotating goblet showed a statistically reliable preference for perceiving the talking profiles as ‘figure’. Deforming the profiles by manipulating the vertex angle of the mouth region produced an inverted U-shaped curve with the peak representing the stimulus condition in which the profiles perception was most remarkable. We discussed a number of 3-D and 2-D figure-ground factors that might apply to this rather complex stimulus situation.

Is it possible to obtain the subjective‐contour effect in touch?

The so‐called subjective‐contour effect was examined in touch and compared with vision. The first experiment was designed to establish a criterion of the subjective pattern by modal completion. In experiment 2, free verbal reports were gathered from naive subjects. Verbal reports and rating scores for three characteristics, subjective pattern, depth displacement, and brightness transformation, were gathered from the well‐trained subjects in experiment 3. Results were as follows. (1) The effect was strong in vision especially for the pattern. Subjective pattern was reported in touch, but, in most other cases, they understood the pattern to be just a triangle or square as a result of bridging, without perceiving the contiguous surface. (2) Subjective depth was not observed so much even in vision by the naive subjects, although it was clear to the well‐trained subjects. When depth displacement was reported, the subjective surface was perceived as more concave than the surface of paper. In conclusion, althoug...