Temperature influences perception of the length of a wielded object via effortful touch

Abstract

Individuals can perceive the properties of an attached or grasped object by wielding it through muscular effort-an ability referred to as dynamic or effortful touch. Sensitivity to the forces required to move such objects and to the resulting global patterns of tissue deformation underlies such perception. Given that perception via dynamic touch is movement-based, we hypothesized that manipulations that affect the ability to produce and control muscular movements might affect perception via dynamic touch. Cooling muscles from 40 to 10 °C impedes the development and transmission of muscular force and diminishes muscle stretch-reflex sensitivity. Accordingly, we anticipated that changes in hand temperature would alter the ability to detect patterns of tissue deformation and thus perception of the properties of wielded objects. In two experiments, participants wielded dowels with different lengths and rotational inertias (Experiment 1) and objects with identical lengths and different rotational inertias (Experiment 2). They reported perceived lengths of these objects, in the absence of vision, in cool (~ 10 °C), neutral (~ 30 °C), and warm temperature conditions (~ 40 °C). Actual length predicted perceived length of the dowels (Experiment 1), and rotational inertia predicted perceived length of the objects (Experiment 2); perceived lengths were longer in the warm condition than in the cool condition. In consideration of known temperature-induced changes in tissue structure and function, our results support the hypothesis that comparable processes underlie the control of movement and perception via dynamic touch.

Proprioceptive afferents differentially contribute to effortful perception of object heaviness and mass distribution

“…These results reflect the everyday experience with perception of object properties: given that the static moment of an object about the point of rotation depends on the force of gravity, an object is perceived lighter when immersed in water than when wielded in the air. In contrast, given that the moment of inertia of an object does not depend on the external forces acting on that object, perceived length of an object is fairly consistent whether that object is wielded in water or the air, as several studies have shown previously (Pagano and Donahue 1999;Pagano and Cabe 2003;Mangalam et al 2017Mangalam et al , 2018.…”

“…Both these findings undermine any association between a simple increase in peripheral afferent feedback and perception of length. Previous findings also indicate a lack of such association, as people can perceive the length of an object with reasonable accuracy under reduced peripheral afferent feedback: by moving an object minimally (Carello et al 1992;Lederman et al 1996), and by wielding an object when it is immersed in water, and the force of buoyancy reduces the force required to wield that object (Pagano and Donahue 1999;Pagano and Cabe 2003;Mangalam et al 2017Mangalam et al , 2018 . Nonetheless, the finding that manipulations of wrist angle and wrist angular kinematics affected perceived length is important.…”

“…It seems that as opposed to perception of heaviness, perception of object properties related to mass distribution relies more on feedback from spindles than from tendon organs. It has been found, for example, that people can perceive the length of an occluded object by wielding in hand with reasonable accuracy even when that object is immersed in water (Pagano and Donahue 1999;Pagano and Cabe 2003;Mangalam et al 2017Mangalam et al , 2018, and the force of buoyancy reduces the force required to wield that object, the central effort, and the peripheral feedback from tendon organs. These studies suggest that feedback from spindles and tendon organs may differentially contribute to the effortful perception of object heaviness and length.…”

Gone Fishin’: Perceiving the length of one object that is non-rigidly attached to a wielded object

“…It is important to point out that functional transparency does not necessarily imply that properties of the wielded object do not matter or that such properties do not influence perception of the properties of the target object or surface (see Barac-Cikoja, 1991, 1993; Burton & McGowan, 1997; Mangalam et al, 2018; Peck et al, 1996). Nor does it imply that perceivers are unable to perceive any properties of the wielded object or are unable to differentiate between properties of the wielded object and the target object (see Carello et al, 1996; Wagman & Duffrin, 2023; Wagman et al, 2020).…”