The Remapping of Peripersonal Space in a Real but Not in a Virtual Environment

Abstract

One of the most surprising features of our brain is the fact that it is extremely plastic. Among the various plastic processes supported by our brain, there is the neural representation of the space surrounding our body, the peripersonal space (PPS). The effects of real-world tool use on the PPS are well known in cognitive neuroscience, but little is still known whether similar mechanisms also govern virtual tool use. To this purpose, the present study investigated the plasticity of the PPS before and after a real (Experiment 1) or virtual motor training with a tool (Experiment 2). The results show the expansion of the PPS only following real-world tool use but not virtual use, highlighting how the two types of training potentially rely on different processes. This study enriches the current state of the art on the plasticity of PPS in real and virtual environments. We discuss our data with respect to the relevance for the development of effective immersive environment for trainings, learning and rehabilitation.

Reshaping the Peripersonal Space in Virtual Reality

“…If the direction of motion is crucial to the reshaping, one might have expected a constriction of the size of the PPS. Going back to the comparison between the present study with that of Ferroni et al [27], it is clear that the condition more similar across the two studies is the Hammer training, in which participants had "physical contact" with the targets but without moving the objects between the PPS and the EPS. Notably, in Ferroni et al [27] such training yielded a weak tendency to shrink the PPS, suggesting that the two kinds of training taken into account, might trigger similar PPS reshaping.…”

“…One of the key contributions of the present study is that it has successfully investigated PPS manipulations in a VR environment, as previous studies have questioned the possibility to do so. For instance, as mentioned in the Introduction, Ferroni et al [27] found that the same kind of training that triggered an expansion of PPS in a real life setting did not achieve the same result in VR, which prompted them to conclude that the PPS in VR might be characterized by different properties. One possible explanation to reconcile these ndings might be in terms of the differences between the experimental paradigm implemented here and in Ferroni et al [27].…”

“…For instance, as mentioned in the Introduction, Ferroni et al [27] found that the same kind of training that triggered an expansion of PPS in a real life setting did not achieve the same result in VR, which prompted them to conclude that the PPS in VR might be characterized by different properties. One possible explanation to reconcile these ndings might be in terms of the differences between the experimental paradigm implemented here and in Ferroni et al [27]. In their paradigm, during the training phase participants had to move an object from point A to point B with both points being located in the EPS.…”

“…However, some concerns have been presented on whether measuring the PPS in VR provides a true representation of the PPS in the real world. Speci cally, Ferroni et al [27] asked participants to perform a short training in which they had to move small objects from point A to point B with a horizontal dragging motion, with both A and B being landing points placed in EPS. This task triggered an enlargement of the PPS when the task was performed in the real world.…”

Human memory for real-world solid objects is not predicted by responses to image displays.

“…Our results raise intriguing questions about the limits and potential for virtual/augmented reality to mimic realness, and about whether awareness or belief that a stimulus is real is a necessary condition for performance differences (Banks et al, 2016). For example, the perception of reachable space surrounding the body can be extended, or “remapped,” following motor training with a real tool, but the same does not happen after motor training with a virtual reality tool (Ferroni et al, 2022). The effect of realness on memory advances various translational predictions, including that real objects may be preferable to pictures for facilitating learning and memory in the classroom (Strouse & Ganea, 2021), for maximizing sensitivity in neuropsychological evaluations (Beaucage et al, 2020; Hampstead et al, 2010), and perhaps for facilitating performance in individuals for whom memory function is disrupted due to brain injury (Sirigu et al, 1991), developmental disorder (Humphreys & Riddoch, 1999), natural aging (Tran et al, 2021), or neurodegenerative conditions (Clemenson & Stark, 2015).…”