Perception of interpolated position and orientation by vision and active touch

Vision and active touch lead to similar patterns of constant error for the perception of interpolated position in twodimensional and one-dimensional regions, though the errors for touch are larger than those for vision. The error patterns for the orientation of a radius of a semicircle are more complex, but can be interpreted as due to the interaction of two sets of anchors rather than the single pair available for the linear interpolation. The greater size of the touch errors is interpreted as due to a relative overestimation of larger distances by active touch or of smallerdistances by vision.     

The role of haptic versus visual volume cues in the size-weight illusion

Three experiments establish the size-weight illusion as a primarily haptic phenomenon, despite its having been more traditionally considered an example of vision influencing haptic processing. Experiment 1 documents, across a broad range of stimulus weights and volumes, the existence of a purely haptic size-weight illusion, equal in strength to the traditional illusion. Experiment 2 demonstrates that haptic volume cues are both sufficient and necessary-for a full-strength illusion. In contrast, visual volume cues are merely sufficient, and produce a relatively weaker effect. Experiment 3 establishes that congenitally blind subjects experience an effect as powerful as that Of blindfolded sighted observers, thus demonstrating that visual imagery is also unnecessary for a robust size-weight illusion. The results are discussed in terms of their implications for both sensory and cognitive theories of the size-weight illusion. Applications of this work to a human factors design and to sensor-based systems for robotic manipulation are also briefly considered.     

Haptic classification of common objects: Knowledge-driven exploration

In Experiment 1, haptically available object properties that would be diagnostic for constrained common object classification at the basic and subordinate levels were elicited in a questionnaire. The results are considered in terms of the nature of the haptically derived representations of common objects. Initial data are also presented regarding knowledge of the natural co-occurrence of properties in haptic object perception. In Experiment 2, the hand movements executed during haptic classification of manipulable common objects were examined. Manual exploration consisted of a two-stage sequence, an initial generalized "grasp-and -lift" routine, followed by a series of more specialized hand-movement patterns strongly driven by knowledge of the property diagnosticity for the specific object (obtained in Experiment 1). The current results may guide computational models of human haptic object classification and the development of perceptual systems for robots equipped with sensate dextrous hands, capable of intelligent exploration, recognition, and manipulation of concrete objects.     

Lateralization for reading musical chords: Disentangling symbolic, analytic, and phonological aspects of reading

It has been repeatedly shown that the left hemisphere (right visual field) is superior to the right hemisphere (LVF) in reading English, a bias possibly due to any or all of three confounded factors: (1) the symbolic nature of the coding system; (2) the analytic requirements of the decoding process; and (3) the phonological associations of the elements. Recent work on reading Japanese ideograms (Kanji) disentangles (1) from (2) and (3), but leaves the latter two confounded. We further disentangle (2) and (3) by examining visual field preference for reading musical chords, representatives of an analytic, nonphonological symbol system. The strong RVF advantage is interpreted as indicating that the left hemisphere is dominant for reading an analytic symbol system that is not phonologically based. We conclude that the left-hemisphere advantage traditionally found for reading phonological symbols is due to their analytic nature in addition to any effect due to their linguistic association.     

Touch: a computerized bibliography.

A computerized bibliography of references relating to "touch" has been prepared. It currently contains approximately 4000 references which belong under the following general categories--physiology and neurophysiology; sensation; perception; cognition; social, cultural, and developmental issues; clinical pathology; the deaf and blind; tactile communication and tactile aesthetics. References have been obtained primarily from the Psychological Abstracts, with classification codes added on the basis of the abstract's content. Master copies and keyword searches may be obtained on the most up-to-date version of the bibliography.     

The orthogonal transformations of a factorial matrix into itself

Certain matrix algebra, pertinent to multiple factor theory, is presented.     

Closed Structure

Journal of Philosophical Logic - According to the structured theory of propositions, if two sentences express the same proposition, then they have the same syntactic structure, with corresponding...     

Face recognition by hand

We investigated participants' ability to identify and represent faces by hand. In Experiment 1, participants proved surprisingly capable of identifying unfamiliar live human faces using only their sense of touch. To evaluate the contribution of geometric and material information more directly, we biased participants toward encoding faces more in terms of geometric than material properties, by varying the exploration condition. When participants explored the faces both visually and tactually, identification accuracy did not improve relative to touch alone. When participants explored masks of the faces, thereby eliminating material cues, matching accuracy declined substantially relative to tactual identification of live faces. In Experiment 2, we explored intersensory transfer of face information between vision and touch. The findings are discussed in terms of their relevance to haptic object processing and to the face-processing literature in general.     

Haptic processing of the location of a known property: does knowing what you've touched tell you where it is?

The relationship between knowing where a haptic property is located and knowing what it is was investigated using a haptic-search paradigm. Across trials, from one to six stimuli were presented simultaneously to varying combinations of the middle three fingertips of both hands. Participants reported the presence/absence of a target or its location for four perceptual dimensions: rough/smooth, edge/no edge, relative position (right/left), and relative orientation (right/left). Reaction time data were plotted as a function of set size. The slope data indicated no difference in processing load for location as compared to identity processing. However, the intercept data did reveal a cost associated with processing location information. Location information was not obtained for "free" when identity was processed. The data also supported a critical distinction between material and edge dimensions versus geometric dimensions, as the size of the cost associated with processing location was larger for spatial than for intensive stimuli.