Representational gravity: Empirical findings and theoretical implications

Abstract

Judgment of the location of a previously viewed moving or stationary target is often displaced in the direction of implied gravitational attraction, and this has been referred to as representational gravity. Variables that have been investigated for a possible influence on representational gravity include characteristics of the target (size/mass, velocity, distance traveled, orientation, modality), display (retention interval, response measure, height in the picture plane), context (nontarget intramodal stimuli, cross-modal components of a single stimulus), and observer (oculomotor behavior, body orientation, psychopathology), and several additional variables that might influence representational gravity but have not yet been investigated are suggested for future studies. Conclusions and speculations regarding the contribution and relationship of representational gravity to several variables, processes, and tasks (physical gravity, linear acceleration, subjective visual vertical, size/mass and weight, other biases in spatial localization, catching and intercepting a moving target, an internal model of gravity, naïve physics, a gravity heuristic, art and aesthetics) are discussed, and compatibility of representational gravity with Gibsonian and representational approaches is noted. It is suggested that representational gravity is an important adaptation that aids observers in interactions with physical objects in the environment, but that such an adaptation is not necessarily fully consistent with objective physical principles.

Motion Perception Investigated Inside and Outside of the Laboratory

“…Overall, the observed data patterns were comparable across both experiments, supporting the idea that the Representational Momentum and Representational Gravity phenomena are robust and can be observed in less controlled situations. That is, the forward shift systematically increased with increasing stimulus speed, whereas the downward shift was not influenced by stimulus speed, both data patterns were in line with findings in the respective literature (e.g., Freyd & Finke, 1985;Hubbard, 1990;Hubbard & Bharucha, 1988; for recent discussions, see Hubbard, 2018Hubbard, , 2020. The present results indicate that similar manipulations result in qualitatively similar changes of the Representational Momentum and Representational Gravity phenomenon, respectively, indicating that these phenomena can be investigated in such online, uncontrolled settings.…”

Visual space orientation and representational gravity: Contextual orientation visual cues modulate the perceptual extrapolation of motion.

“…The main finding of the present experiment is that the spatial localization of the offset position of a moving target, thought to reflect an internalized representation of implied dynamics (e.g., De Sá Teixeira, 2016; Hubbard, 2014; Lacquaniti et al, 2013), is significantly and lawfully modulated by the orientation of the visual context. This outcome bears particularly on the conceptualization of representational gravity, commonly referred to as a perceptual displacement “downward” in the direction of gravity (Hubbard, 2020), amplifying/attenuating representational momentum for ascending/descending targets. In line with the extant literature on spatial orientation (e.g., De Vrijer et al, 2008, 2009; Dyde et al, 2006; Howard, 1982; MacNeilage et al, 2008; Mittelstaedt, 1986), the “downward” direction underlying representational gravity possesses a multifactorial nature, determined in part by the gravito-inertial vector, as sensed by the vestibular system (De Sá Teixeira et al, 2017), the body’s main axis orientation (idiotropic vector; De Sá Teixeira, 2014; De Sá Teixeira & Hecht, 2014b), and, based upon the presently reported findings, contextual orientation visual cues.…”

“…A prominent tenet in contemporary research on the visual perception of events holds that humans possess internalized representational analogues of physical principles, such as momentum, friction, and gravity, in the form of internal models (Grush, 2005; Lacquaniti et al, 2013; Tin & Poon, 2005; Zago & Lacquaniti, 2005) and are thought to support the anticipation of seen or experienced dynamics, so as to aid subsequent motor interactions (McIntyre et al, 2001; Tresilian, 2004, 2005; Zago et al, 2008). Among the several perceptual phenomena that have been linked to the functioning of these putative internal models (Lacquaniti et al, 2013) is representational momentum (for reviews, see Hubbard, 2005, 2010, 2014) and the closely related representational gravity (for a review see Hubbard, 2020), both measurable through a simple spatial localization task.…”

Newtonian Predictions Are Integrated With Sensory Information in 3D Motion Perception

“…As a result, we remain agnostic about the nature of the predictive mechanism. In particular, the observed phenomenon does not necessitate a detailed internal model of Newtonian mechanics (e.g., Battaglia et al, 2013) but instead could be the result of learned contingencies between perceived events in a Newtonian environment (Hubbard, 2020; Shepard & Chipman, 1970). Setting aside this larger debate, some of our data suggest that the predictive mechanism is activated only when the collision event is perceived as causal (Michotte, 1946/1963).…”

“…In recent years, however, the internalization hypothesis has resurfaced as a hotly debated topic. Proponents point to evidence suggesting that the visual system is indeed sensitive to the latent physical quantities involved in Newtonian mechanics, such as mass distribution (Battaglia, Hamrick, & Tenenbaum, 2013; Firestone & Keil, 2016; Firestone & Scholl, 2014), force (Freyd, Pantzer, & Cheng, 1988; Hubbard, 2013), momentum (Freyd, 1983; Hubbard, 2019), and gravity (Hubbard, 2020; McIntyre, Zago, Berthoz, & Lacquaniti, 2001). Additionally, optimal-inference models have successfully accounted for human judgments in complex physical scenes by combining sensory observations with internal models that accurately represent Newtonian mechanics (Battaglia et al, 2013; Sanborn, Mansinghka, & Griffiths, 2013).…”