Assume a Spherical Chicken: Analytic Constraints, Inertia Tensor Information, and Wielded Rod Length Perception.

Information associated with the inertia tensor is the preeminent explanation for haptic perception of object properties, notably wielded rod length. Critics counter that tensorial-based information requires non-tensorial supplementation (mass, torque). However, those critiques omit important constraints.

Squeaky wheels: Friction-generated sound supports auditory differentiation and scaling of rotating ellipse shapes.

Acoustical analysis indicates that sounds generated as the rims of ellipses rotate against a fixed contactor vary regularly with ellipse shapes (defined by minor-to-major axis length ratios), potentially supporting human ability to differentiate and scale the shapes. In four experiments, we documented human ability to do so. Experiment 1 demonstrated reliable and ordinally correct shape judgments.

Multi-Image Pinhole Viewer Using a Biscuit.

A camera obscura-type viewer based on pinhole optics, with the apertures being the holes in a commercial snack biscuit (or cracker), produces interesting and easily obtainable projected images, as demonstrated during the 2017 solar eclipse.

Haptic distal spatial perception mediated by strings: size at a distance and egocentric localization based on ellipse geometry.

Participants explored ellipse perimeters defined by fixed-length strings, held taut by their moving finger, with ends attached to two fixed hooks (foci). Participants haptically judged ellipse interfocal distance (IFD; in effect, exocentric separation, or size at a distance) or location of ellipse major axes (i.e.

Haptic distal spatial perception mediated by strings: point of closest approach and bypass distance.

Four experiments examined haptic perception of two distal spatial properties in a bypass event. A hook suspended a string held taut between the participant's finger and a weight. Moving their fingers laterally beneath the hook, participants estimated the finger's point of closest approach (PCA) to the hook and bypass distance (BPD; i.

Haptic distal spatial perception mediated by strings: haptic "looming".

Five experiments tested a haptic analog of optical looming, demonstrating string-mediated haptic distal spatial perception. Horizontally collinear hooks supported a weighted string held taut by a blindfolded participant's finger midway between the hooks. At the finger, the angle between string segments increased as the finger approached collinearity with the hooks, just as the optical angle subtended by an approaching object increases.

Characterizing perceptual learning using regression statistics: development of a perceptual calibration index.

Perceptual learning, improvement in perceptual skill with practice, can improve both accuracy and consistency of perceptual reports. Regression statistics can quantify ongoing calibration of perceptible scalar properties (i.e.

Sufficiency of longitudinal moment of inertia for haptic cylinder length judgments.

Many studies invoke moment of inertia (Iii) as necessary and sufficient information to perceive cylinder length via wielding, yet some assert that Iii is neither necessary (weight, m, or static moment, M, are sufficient) nor sufficient for length judgments (m or M is necessary). Mathematical expressions for Iii not involving m or M imply length, so Iii could be sufficient for cylinder length judgments. In 5 experiments (N = 113), only longitudinal Iii (the smallest principal value) informed cylinder length estimates in a novel task, rolling.

Descartes's blind man revisited: bimanual triangulation of distance using static hand-held rods.

Analogous to binocular convergence, we tested Descartes's proposal that a blind person could triangulate distances using crossed hand-held rods by sensing hand separation and wrist angles. In Experiment 1, 22 participants judged distances to loci at 4 distances, 18-36 in. (45.