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As Easy to Move as a Feather: Perception of Lightness as Ease to Move
Abstract
When perception by touch is couched in terms of movement, perception of heaviness can be understood as perception of difficulty to move. This experiment further investigated this proposal as well as the corollary proposal that perception of lightness may be understood as perception of ease to move. Blindfolded participants wielded weighted objects and rated how heavy or light each object felt and how difficult or easy each object was to move. Ratings of heaviness and difficulty to move were analogously constrained by movement-relevant variables. Ratings of lightness and ease-to-move were also analogously constrained by such variables, but in the opposite manner. Conventional descriptors such as heaviness or lightness may be inappropriate for a principled understanding of perception by touch.
... The second possibility is that, since GRFs affect the ease with which a gyroscope's axis can be reoriented to a specified orientation, this difference in object movability will be detected as a difference in mass distribution. Some past studies (Shockley et al., 2004;Turvey & Carello, 1995;Turvey et al., 1999;Wagman, 2015) have attributed heaviness perception to an object's movability (or moveableness), noting that total mass is but one factor that affects movability. Increases in the first and second mass moments each mean an increase in the forces required to move and reorient the object. ...
Gyroscopes have long been known as perceptual novelties. Attempts to change the orientation of a gyroscope’s axis generate gyroscopic reactive forces (GRFs). When rigid objects are wielded, forces applied by objects to the limbs and body of wielders are the basis of a haptic perception of properties (e.g. length and mass) of the objects. In two experiments, we examine the forces produced by gyroscopes and their effect on the wielders’ perceptual judgments. In Experiment 1, angular momentum is perceived as additional mass when wielding motions such that GRFs supplement torque about the wrist in the same direction as added mass and as reduced mass when GRFs are in the opposite direction. In experiment 2, neither the magnitude nor the direction of the GRFs affected judgments of object length, even though longer rigid objects increase torque about wielders’ wrists. We interpret the results in the context of past research on movability and perception of object length and heaviness.
... However, the argument being made by those authors was that perception of the action-neutral property depends on perception of the action-referential property and not the other way around. In other words, colloquial descriptors such as ''heavy'' and ''light'' may simply be inappropriate for a principled understanding of perception by touch (Wagman, 2015). A similar argument could be made about perception in general-action-referential properties (i.e., affordances) may be fundamental to perception, perhaps more fundamental than action-independent (i.e., metric) properties (cf. ...
Two experiments were conducted to explore how the calibration of perception of environmental properties taken with reference to an animal and their action capabilities (e.g., affordances) and those that are independent of action capabilities (e.g., metric properties) relate. In both experiments, participants provided reports of the maximum height they could reach above their head with a number of different stick(s) (reach-with-stick height) and the length of those stick(s), a property that is a constituent of reach-with-stick height. In Experiment 1 reach-with-stick height reports improved over trials whereas stick length reports remained constant. In Experiment 2, feedback about maximum reach-with-stick height improved perception of this affordance, but such improvements did not transfer to perception of stick length in a pretest/practice task/posttest design. The results suggest that the perceptual calibration with practice perceiving or feedback about actual dimensions of action-referential and action-neutral properties do not necessarily depend on one another.
... Although there are a number of explanations for this phenomenon, the one favored by ecological psychologists draws an explicit link between touch and movement. In such an explanation, the (higher-order and animal dependent) stimulation variable of relevance is the resistance to rotational acceleration in different directions about a joint (instead of mass or volume) and the experience on the part of the perceiver is "ease or difficulty to move" (instead of heaviness, see [8]). The more diverse the muscular forces required to control an object, the more difficult that object is to control, and the heavier it feels. ...
Though not necessarily one of the stated goals, tihs book goes a long way toward helping touch to shed its undeserved underdog status. The authors situate perception by touch (perhaps in its rightful place) at the intersection of a number of disciplines including psychophysics, cognitive psychology, neuroscience, low vision and blindness, applied psychology, and engineering. The authors have had long and distinguished careers investigating perception by touch in both visually impaired and sighted individuals and have made important contributions in these areas. To some extent, this book is an overview of this (and related) research, though it is also much more than that. As the title implies, the book places particular emphasis on the haptic abilities of visually impaired and blind individuals. However, it also focuses on using the haptic abilities of sighted individuals to understand those of blind individuals, and vice versa. This is perhaps its most valuable contribution. In addition, it provides useful historical and theoretical context for research on the haptic abilities of both populations of people. Finally, it not only provides an overview of the ground already covered but also a preview of the ground yet to be covered, especially considering the recent technological advances in haptic interfaces and related technology.
In addressing the character of the haptic system, James Gibson (1966) noted, “The study of useful sensitivity, as distinguished from theoretically basic sensitivities, is only just beginning” (p. 116). Whereas the preceding 150 years had gotten mired in an inventory of isolated sensations, the ensuing 50 years have revealed a good deal about the capabilities of a perceptual system that detects information about the self, the environment, and self-environment relations by means of muscular effort. That research is summarized with special attention to the kind of medium that could ground the useful dimensions of haptic sensitivity.
Weight illusions-where one object feels heavier than an identically weighted counterpart-have been the focus of many recent scientific investigations. The most famous of these illusions is the 'size-weight illusion', where a small object feels heavier than an identically weighted, but otherwise similar-looking, larger object. There are, however, a variety of similar illusions which can be induced by varying other stimulus properties, such as surface material, temperature, colour, and even shape. Despite well over 100 years of research, there is little consensus about the mechanisms underpinning these illusions. In this review, I will first provide an overview of the weight illusions that have been described. I will then outline the dominant theories that have emerged over the past decade for why we consistently misperceive the weights of objects which vary in size, with a particular focus on the role of lifters' expectations of heaviness. Finally, I will discuss the magnitude of the various weight illusions and suggest how this largely overlooked facet of the topic might resolve some of the debates surrounding the cause of these misperceptions of heaviness.
G*Power is a free power analysis program for a variety of statistical tests. We present extensions and improvements of the version introduced by Faul, Erdfelder, Lang, and Buchner (2007) in the domain of correlation and regression analyses. In the new version, we have added procedures to analyze the power of tests based on (1) single-sample tetrachoric correlations, (2) comparisons of dependent correlations, (3) bivariate linear regression, (4) multiple linear regression based on the random predictor model, (5) logistic regression, and (6) Poisson regression. We describe these new features and provide a brief introduction to their scope and handling.
G*Power (Erdfelder, Faul, & Buchner, 1996) was designed as a general stand-alone power analysis program for statistical tests commonly used in social and behavioral research. G*Power 3 is a major extension of, and improvement over, the previous versions. It runs on widely used computer platforms (i.e., Windows XP, Windows Vista, and Mac OS X 10.4) and covers many different statistical tests of the t, F, and chi2 test families. In addition, it includes power analyses for z tests and some exact tests. G*Power 3 provides improved effect size calculators and graphic options, supports both distribution-based and design-based input modes, and offers all types of power analyses in which users might be interested. Like its predecessors, G*Power 3 is free.
The haptic subsystem of dynamic touch is sensitive to the relation between a held object's distribution of mass and the object's affordances. In four experiments participants used dynamic touch to gauge the suitability of differently weighted hockey sticks for performing power (transferring maximal force) and precision (intercepting a moving object) actions. Results showed that perceivers could use dynamic touch to perceive the affordances of the hockey sticks. Perceptual sensitivity to action-relevant object properties was modified when novice participants were given the opportunity to discover subtle task constraints by actually performing the hockey tasks. Expert (collegiate-level) hockey players' ratings reflected attunement to the constraints that prompted changes in novices' responses.
In the most general case, haptic perception of an object's heaviness is most likely the perception of the object's resistance to movement, determined jointly by the object's mass and mass distribution. In two experiments with occluded objects wielded freely in three dimensions, we showed additive effects on perceived heaviness of mass and the inertia tensor. Our manipulations of the inertia tensor were directed specifically at the volume and symmetry of the inertia ellipsoid, quantities that can be understood as important to controlling the level and patterning of muscular forces, respectively. Ellipsoid volume and symmetry were found to have separate effects on perceptual reports of heaviness that were invariant over different tensors. Independent sensitivities to translational inertia and particular characterizations of rotational inertia suggest specialized somatosensory attunement to the rigid body laws.
It is hypothesized that heaviness perception for a freely wielded nonvisible object can be mapped to a point in a three-dimensional heaviness space. The three dimensions are mass, the volume of the inertia ellipsoid, and the symmetry of the inertia ellipsoid. Within this space, particular combinations yield heaviness metamers (objects of different mass that feel equally heavy), whereas other combinations yield analogues to the size-weight illusion (objects of the same mass that feel unequally heavy). Evidence for the two types of combinations was provided by experiments in which participants wielded occluded hand-held objects and estimated the heaviness of the objects relative to a standard. Further experiments with similar procedures showed that metamers of heaviness were metamers of moveableness but not metamers of length. A promising conjecture is that the haptic perceptual system maps the combination of an object's inertia for translation and inertia for rotation to a perception of the object's maneuverability.