PubMed · 5013343
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T C Daniel, H C Ellis. 1972. Stimulus codability and long-term recognition memory for visual form.. https://doi.org/10.1037/h0032486
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Curvature discrimination of hand-sized doubly curved surfaces by means of static touch was investigated. Stimuli consisted of hyperbolical, cylindrical, elliptical and spherical surfaces of various curvatures. In the first experiment subjects had to discriminate the curvature along a specified orientation (the discrimination orientation) of a doubly curved surface from a flat surface. The curvature to be discriminated was oriented either along the middle finger or across the middle finger of the right hand. Independent of the shape of the surface, thresholds were found to be about 1.6 times smaller along the middle finger than across the middle finger. Discrimination biases were found to be strongly influenced by the shape of the surface; subjects judged a curvature to be more convex when the perpendicular curvature was convex than when this curvature was concave. With the results of the second experiment it could be ruled out that the influence of shape on curvature perception was simply due to a systematic error made by the subject regarding the discrimination orientation.
We measured the three-dimensional shape and two-dimensional surface reflectance contributions to human recognition of faces across viewpoint. We first divided laser scans of human heads into their two- and three-dimensional components. Next, we created shape-normalized faces by morphing the two-dimensional surface reflectance maps of each face onto the average three-dimensional head shape and reflectance-normalized faces by morphing the average two-dimensional surface reflectance map onto each three-dimensional head shape. Observers learned frontal images of the original, shape-normalized, or reflectance-normalized faces, and were asked to recognize the faces from viewpoint changes of 0, 30 and 60 degrees. Both the three-dimensional shape and two-dimensional surface reflectance information contributed substantially to human recognition performance, thus constraining theories of face representation to include both types of information.
Recent studies have used grating orientation as a measure of tactile spatial acuity on the fingerpad. In this task subjects identify the orientation of a grooved surface presented in either the proximal-distal or lateral-medial orientation. Other recent results have suggested that there might be a substantial anisotropy on the fingerpad related to spatial sensitivity. This anisotropy was revealed using a task in which subjects discriminated between a smooth and a grooved surface presented at different orientations on the fingerpad. The anisotropy was substantial enough that it might permit subjects to discriminate grating orientation on the basis of intensive rather than spatial cues. The present study examined the possibility that anisotropy on the fingerpad might provide cues in a spatial acuity task. The ability of subjects to discriminate between a smooth and a grooved surface was measured under conditions that are typically used in grating orientation tasks. No evidence of anisotropy was found. Also, using a grating orientation task, separate estimates were made of sensitivity in the proximal-distal and lateral-medial orientations. Again no evidence of anisotropy was found. Consistent with changes in the density of innervation, grating orientation sensitivity was found to vary as a function of location on the fingerpad. The results support the view that grating orientation is a valid measure of spatial acuity reflecting underlying neural, spatial mechanisms.