Perceiving aperture size by striking.

Abstract

This study examined the ability to perceive surface separation on the basis of mechanical stimulation resulting from striking the surfaces' interiors with a hand-held rod. The variables manipulated were aperture size, angular displacement theta, distance b of the point of contact with the surfaces from the axis of rotation, hand-rod mass m, location of the hand-rod's center of mass a, and moment of inertia Io of the hand-rod. Given a particular rod and an aperture at a given distance, lambda = sin(theta/2)[1 - (2a/b) + (ma2/Io)] was invariant over explorations. Perception of aperture size was specific to lambda; it predicted successfully the interdependent effects of theta, b, and the mechanical properties of the implement. The results of 7 experiments were discussed in terms of the specificity of perception to information and the general ability to perceive distant things by means of body appendages.

Does perceived size depend on perceived distance? An argument from extended haptic perception

“…Both experiments revealed a haptic capability to discriminate reliably among occluded gap sizes (in agreement with Barac-Cikoja & Turvey, 1991, 1993 and gap distances (in agreement with Carello et aI., 1992;Chan & Turvey, 1991) when the gaps were contacted with a hand-held rod. In both experiments, it was shown that S' changed with changes in both Sand D, whereas D' was unaffected by changes in S. Previous studies (Barac-Cikoja & Turvey, 1991, 1993 demonstrated a complex dependence of S' on inertial characteristics (frod' m, a) of the probe used in exploration of the surface layout, which was only hinted in the results of Experiment 2. Separate, significant effects of inertial characteristics ofthe probe on D' were demonstrated on the pooled data from the two experiments.…”

“…In previous research, variations in the rate at which S' changes with S were predicted by the partial derivative of A, with respect to S-a quantity composed solely from the observables a, b, and p (Barac-Cikoja & Turvey, 1993). Given a hypothesis of information-perception specificity (e.g., Barac-Cikoja & Turvey, 1991, 1993Gibson, 1979Gibson, /1986, it is expected that failures of visual size constancy and variations in the actual size derivatives of perceived size are similarly explainable. In Equations 1 and 2, there is only D (corresponding to the quantity b in the haptic equations) and D', respectively, to scale angle.…”

“…Following Gibson's argument, however, one might ask whether there is an alternative hypothesis founded on an invariant of the mechanical energy distribution patterned by the activity of striking the gap. Mechanical analysis reveals a collective parameter Athat connects the muscular forces applied to the probe to the reactive forces impressed on the tissues of the arm (see Barac-Cikoja & Turvey, 1991, 1993, for the derivation of A). The measurable quantity Arelates several variables:…”

Spatial and physical frames of reference in positioning a limb

“…The eigenvectors ek and rotation of {e } were computed for each splint + forearm combination usmg re~ression equations and procedures provided by Reynolds (1978; see also Chandler, Clauser, McContville, Reynolds, & Young, 1975;Clauser, McContville, & Young, 1969) applied to the body dimensions of an averaged-sized person. (For an overview of the regression equations and body dimensions used in the calculations see Barac-Cikoja & Turvey, 1993, Pagano et al, 1996, Pagano & Turvey, 1995. From these regression equations, the mass, distances of the centers of mass (CM) of the forearm and the hand from the pomt of rotation in the elbow, and principal moments of inertia for the limb segments were computed.…”

Self-training of dynamic touch: Striking improves judgment by wielding

“…The role of mechanical contact from striking has been studied in dynamic touch, but only as a single exploratory style. The evidence from studies on both wielding and striking suggest that they provide different kinds of mechanical information about length (Barac-Cikoja & Turvey, 1991;Carello, Fitzpatrick, & Turvey, 1992;Chan & Turvey, 1991). Research in dynamic touch has yet to evaluate the role of striking in modulating judgments by wielding.…”