How the Human Brain Solves the Symbol-Grounding Problem

Abstract

A fundamental issue in cognitive science is the so-called “symbol-grounding problem” (Harnad 1980), related to the question of how symbols acquire meaning. One simple view posits that, for concrete words, our brain solves the problem by creating associations between the neural representations of the surface forms of symbols (spoken or written words) to the one(s) evoked by the object, action, or event classes the symbols refer to (e.g., see Pulvermuller 2013; 2018). Evidence supporting this view comes from the observation that words related to well known concepts such as numerical quantities (Piazza et al. 2007; Eger et al. 2009), colors (e.g. Simmons et al. 2007), manipulable objects (Chao et al. 1999), places (Kumar et al. 2017), or actions (Hauk 2004; 2011), automatically re-activate the same brain regions that are active during the perception/execution of those specific object features/actions. These data, however, are informative on the neural bases of symbol grounded representations, but not on those underlying symbol grounding: i) they fall short in assessing the role of memory systems implicated in this kind of symbol-toconcept associative learning, and ii) they do not provide a full picture of the effects that symbol grounding has on the brain. Here, to investigate the neural changes generated by this process, we adopted an artificial learning paradigm where 21 adult subjects learned to categorize novel multisensory objects by giving them specific symbolic labels.