Support for the cue-heuristic model is based on suboptimal observer performance: Response to Gilden and Proffitt (1994)

Abstract

Gilden and Proffitt (1994) have derived support for their updated cue-heuristic model of mass discrimination in observed collisionsfrom two experiments reported by Runeson and Vedeler (1993In a way potentially relevant for perception, the kinematics of colliding objects contain information that specifies the ratio of the objects' masses and about their efficient elasticity (Runeson, /1983. This finding has been generalized and applied to both animate and inanimate events. Thus the expression kinematic specification of dynamics, or the KSD-principle for short, is used to identify a category of informative relations, granted by basic natural laws and ecological constraints (Runeson & Frykholm, 1983; see also Runeson, 1994a).When a certain type of information is shown to exist, it raises the possibility that it might be exploited by per- ceivers. The prospects are strengthened when, as in the case of KSD, the type of environmental properties specified appears to be of relevance for organisms in planning and performing their actions. Thus it was suggested that, although mass and elasticity are "hidden" dynamic properties of objects, they might nevertheless be perceivable by vision (Runeson, /1983.In collision events, the information for mass ratio resides in higher order properties (invariants) of the pattern of motions. The informative relation can be described in several ways. For collisions in one dimension,where mA and mB are the masses of the two objects, and U and v designate the velocities before and after impact (Figure 1). For collisions in two and three dimensions, the same equation can be used if the motions are projected on the collision axis. However, one can also use a generalized equation in which motion vectors replace the velocities:Furthermore, observing that each (v -u) term stands for change in motion in an object, we can set w = v -u and get (3) where W A and w B are collinear vectors that describe the changes in motion incurred by the objects in the collision. Thus, in the most compact form, the ratio of mass is inversely proportional to, and hence uniquely specified by, the relative amount ofmotion change incurred by the two objects in the collision.In the following discussion, it is important to consider the ontological implications of this set of alternative equations. Their variety shows that there is no necessity to register vector components of the motions, or to derive them as projections on any explicit or implicit axes. Nor is it necessary to register trajectory parameters (e.g., speeds and directions) or individual motion vectors, inasmuch as a change in motion is equally well a kinematic property. Hypothetically, it is therefore possible that motion change could be picked up directly by a suitably 'evolved and attuned perceptual system (i.e., a smart perceptual mechanism; Runeson, , 1994b. Indeed, the same possibility exists for the relative amount of change in two moving objects, hence the mass ratio might be directly perceivable as a single property. The plausibility of such a fu...

Learning to perceive the relative mass of colliding balls: The effects of ratio scaling and feedback

“…Variables that specify relative mass have been pitted against nonspecifying variables as predictors ofjudgments of relative mass. A brief review of the physics of collisions permits us to describe the relevant variables (see also Runeson, 1995). The imaginary line that connects the centers ofcolliding balls at the moment of impact is called the collision axis.…”

“…Because kinetic properties of the environment are important for the guidance of action, it would be beneficial for animals to perceive them visually, and indeed, humans, for instance, have been shown to perceive kinetic properties (e.g., Michotte, 1963;Runeson & Frykholm, 1983). The fact that the optical array consists only of kinematic variables creates a problem: How are kinematic variables exploited in the perception of kinetic properties?The nature ofthis exploitation has been debated by proponents ofthe theory ofdirect perception (Runeson, 1995; Runeson, Juslin, & Olsson, in press; Runeson & Vedeler,The Netherlands Organization for Scientific Research (NWO) is gratefully acknowledged for funding this project. This research was conducted while D.MJ.…”

“…The nature ofthis exploitation has been debated by proponents ofthe theory ofdirect perception (Runeson, 1995; Runeson, Juslin, & Olsson, in press; Runeson & Vedeler,…”

“…Correspondence concerning this article should be addressed to D. M. Jacobs, Faculty of Human Movement Science, Vrije Universiteit, van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands (e-mail: djacobs@fbw.vu.nl). , 1994Todd & Warren, 1982). The theory ofdirect perception assumes that kinetic properties of the environment are specified by kinematic patterns.…”

Perspective distortion of trajectory forms and perceptual constancy in visual event identification

“…determine specific kinematic (i.e., motion) patterns and that observers can determine the nature of an event from the resulting patterns of motion. The specific nature of the patterns that allowed recognition of the human motions was not described, although a potential source of information about relative mass in collisions was described and investigated (Runeson, /1983Runeson & Vedeler, 1993), with some ensuing controversy (Gilden & Proffitt, 1989, 1994Runeson, 1995). 1 Following an investigation of trajectories as information about lifted weight (Bingham, 1987b), proposed that trajectory forms are the information used to identify events.…”