The grounding of abstract concepts in vision and action

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Concepts held in semantic long-term memory are important building blocks of human cognition because they establish the meaning of language and thought. Traditionally, concepts are specified as amodal mental entities different from the perceptual or motor systems. More recent modality-specific approaches propose that concepts are essentially grounded in perception and action. For concrete concepts such as hammer, a modality-specific grounding of concepts has been demonstrated. However, for abstract concepts like truth the assumption of an amodal symbolic representation holds a largely unquestioned dogma-like status. Previous evidence regarding an involvement of the sensory-motor systems in the processing of abstract concepts is inconsistent thereby questioning the generality of grounded cognition theories. These inconsistencies could reflect an unknown varying contribution of sensory or motor modalities to the conceptual representation of abstract words. In this project, we therefore develop a new empirical approach by first specifying the content of abstract concepts. We then test whether visual or action-related abstract concepts are processed in the corresponding modality-specific system. In the first series of experiments, we investigate the grounding of abstract concepts in the sensory and motor systems of the human brain by measuring brain activity with event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI) during abstract word recognition. The high temporal resolution of ERPs complements the high spatial resolution of fMRI and allows us to distinguish whether sensory-motor activity in response to abstract words reflects early access to conceptual features or later imagery. Measurements of brain activity with ERPs or fMRI might reveal activity in the sensory-motor system, which only plays an epiphenomenal role. The second series of experiments therefore tests with transcranial magnetic stimulation (TMS) and behavioral interference experiments the functional role of visual and motor representations for the processing of abstract concepts. Grounded cognition theories predict that conceptual representations are established by the learning-based formation of cortical cell assemblies in sensory-motor areas during the course of concept acquisition. Experience-dependent plasticity of abstract physical concepts will be assessed in the third series of experiments with fMRI. We investigate the neural correlates and the content of abstract physical concepts in expert physicists and beginners (2nd year physics students). With these complementary lines of experiments, we expect to gain novel insights into the role of sensory and motor representations for abstract concepts. Moreover, we will be able to determine how modality-specific representations contribute to excellence in experts. Our research thus will yield new results that will influence fields beyond psychology and cognitive neuroscience such as education and teaching.