Kinematic form and scaling: Further investigations on the visual perception of lifted weight.

Abstract

Observers are able to judge accurately the weight hfted by another person when only the motions of reflectwe patches attached to the hfter's major hmb jomts and head can be seen (Runeson & Frykholm, 1981) What properttes of these complex kinematic patterns allow judgments of wetght to be made 9 The pattern of vanaUon m veloctty of the hfied object over posmon ~s explored as a source of mformat~on for wetght It ts found to provtde hmtted mformat~on How are variations m kmemaUc patterns scaled to allow judgments of wetght, a ionet~c quanUty9 The posstbd~ty of a source of m formauon for scaling in the Ionematlcs ts mvesUgated Judgments based only on patch-hght chsplays are accurate to a degree that is ,reproved by an extrms~c scahng basts Fmally, the sensttlvaty to scaling of alterna)ave metrics used m judging ts explored Intrlnstc metrics are dtscovered to be less sens~ttve to the absence of an extrlnstc basts for scahng Observers are able to judge with good accuracy the amount of weight be|ng hfted by another person when only the motions of reflectwe patches attached to the htter's major hmb joints and head can be seen (Runeson & Frykholm, 1981). How is th~s possible? Runeson and Frykholm (1981, 1983) suggest that umque patterns of moUon result from mechan|cal constraints on the hfter's acUvlty They have formulated a principle called KSD, or kinematic spec|fication of dynamics, which states that lonemat~c patterns specify to observers varmt~ons in the values of dynamic factors. Further, Runeson and Frykholm (1983) propose that the mformatwe value of lonemaUc properties of These experiments were included m a doctoral dissertation submttted at the Umverstty of Connecticut, Storrs, Connecttcut The research was supported by a Fulbnght-Hays Pre-doctoral Full Grant for Study Abroad and a Umverstty of Conneclacut Pre-doctoral Fellowshtp awarded to the author, as well as a Swedtsh Counol for Research tn the HumamUes and Sooal Soences (HSFR) award to Sverker Runeson The writing was supported in part by a Nattonal Institutes of Health Indwldual Fellowship Award (AM-07412) Research was performed both at the Umverstty of Connecttcut and at the Umvers~ty of Uppsala, Uppsala, SwedenHeartfelt thanks go to Sverker Runeson, whose work and tdeas msptred the present effort I gratefully acknowledge the help and advice of Sverker Runeson, Ball Mace, Bob Shaw, Mtchael Turvey, Carol Fowler, Len Katz, and Dave Mdler, as well as the constructtve cnlaosm provtded by Jtm Cuttmg and two anonymous reviewers Thanks also to Lars-Enk Larsson, Gunnar Agren, and Lars Beckstrom for proxqdmg mvaluable techmcal asststance I also am grateful to the faculty and students at the Department of Psychology m Uppsala and to the staffat the Swedish Fulbnght Commtsmon for malong my tenure at Uppsala an extraordmardy pleasant and ennchmg experience It was a pnxqlege to part~ctpate m the tradmon of research m event perceptton mtuated by Gunnar Johansson and earned on by Sverker Runeson I shall long benefit from the opportumty Correspondence concerning thts ar...

Observing object lifting errors modulates cortico-spinal excitability and improves object lifting performance

“…Consistent with this proposal, a variety of studies have demonstrated that humans are surprisingly adept at acquiring useful information, such as object weight, from the observed visual kinematics of others' lifts (Bingham, 1987;Hamilton et al, 2007). Not only are individuals able to use these kinematic cues, but there is emerging evidence that the link between acting and perceiving is an automatic one.…”

Trajectory forms as a source of information about events

“…Symmetrical peakening or flattening of trajectory forms are likewise potentially important. Bingham (1987) found that the flattening of an otherwise round harmonic form provided information to observers that the amount of weight being lifted by a person was near to the maximum liftable. Also, because asymmetry entails a change in the peakedness of a form, studying symmetrical peakening helps to differentiate the relative sensitivities to asymmetrical versus peakedness variations of trajectory forms.…”

Rotational kinematics influence multimodal perception of heaviness

“…For example, Runeson andFrykholm (1981, 1983) and Bingham (1987Bingham ( , 1993 demonstrated that the weight of objects lifted by others can be perceived solely via the kinematics of point-light displays. Those studies were conducted prior to the discovery of the inertial basis of heaviness perception; the researchers, therefore, were not in a position to make the conceptual links between inertia and kinematics proposed in the present research.…”

“…Our approach was inspired by studies that have demonstrated that dynamical aspects of events, such as the relative mass of colliding objects (e.g., Flynn, 1994;Gilden & Proffitt, 1989;Runeson, 1977Runeson, /1983Todd & Warren, 1982) or the mass of lifted objects (e.g., Bingham, 1987Bingham, , 1993Runeson & Frykholm, 1981, 1983, can be perceived despite the fact that only motion (i.e., not forces) is visually accessible. The lawful relation between motion and dynamics inspired Runeson's kinematic specification of dynamics (KSD) principle.…”