A handy project : owning, perceiving, and experiencing hands

Abstract

The purpose of this thesis is to explore the mental representation of hands in the context of owning, perceiving, and experiencing hands. The theoretical knowledge of the thesis is discussed in the first chapter, considering the wider concept of body representation. The second chapter reports the data from a study exploring the relationship between the sense of ownership of hands and motor control. The kinematic features of participants’ hands' movements were recorded using a motion analysis capture system and the associated brain activity was recorded using a near-infrared-spectroscopy device. Thirty-two healthy individuals participated in the study. The data show that the embodiment of a rubber hand through touch without vision does not influence the planning and execution of grasping actions (kinematic and brain imaging data). The third chapter presents a study exploring the influence of disgust on the mental representation of hands and feet in action, or motor imagery (MI). Thirty-six healthy individuals were enrolled (different participants from the study in chapter two). The data show that disgust enhances performance on MI tasks. The fourth chapter further expands the knowledge of hands-related MI abilities by comparing hand-based and foot-based MI tasks on a more implicit and explicit level (i.e. action monitoring required to solve the task). Fifty-five healthy participants participated in the data collection (different participants from the study in chapter three). Data show how differences in the mental representation of hands and feet in action imagery are specific to the degree of monitoring required, occurring only when the task is implicit; in other words, when the degree of action monitoring decreases. In the fifth chapter, a comparison between the data obtained in MI tasks executed in laboratory-based and online-based settings is presented, as the pandemic led to the opportunity to explore this aspect. This comparison shows comparable results between settings. Finally, in the sixth chapter, a general discussion of the thesis is presented, reasoning on the limitations of the various experiments and their impact. With the current thesis, I further expand the knowledge on the mental representation of hands, also considering feet as opposite body districts to hands. More in detail, my findings highlight i) that the application of the somatic RHI does not influence motion planning and execution (i.e. maximum GA) (owning hands), ii) that disgust influences our ability to mentally rotate hands and feet (perceiving hands), iii) and that the mental representation of hands and feet in action presents differences specific to the degree of action monitoring involved in solving the task (experiencing hands). The mental representation of hands is dynamic and can be influenced differently by different factors.