Varieties of abstract concepts and their grounding in perception or action

For a very long time, theorizing in the cognitive sciences was dominated by the assumption that abstract concepts, which lack a perceivable referent, can only be handled by amodal or verbal linguistic representations. In the last years, however, refined grounded cognition theories emphasizing the importance of emotional and introspective information for abstract concepts, in addition to verbal associations and sensorimotor information, have received increasing support. Here, we review theoretical accounts of the structure and neural basis of conceptual memory and evaluate them in light of recent empirical evidence with regard to the processing of concrete and abstract concepts. Based on this literature review, we argue that abstract concepts should not be treated as a homogenous conceptual category, whose meaning is established by one single specific type of representation. Instead, depending on the feature composition, there are different subgroups of abstract concepts, including those with strong relations to vision or action, which are represented in the visual and motor brain systems similar to concrete concepts. The reviewed findings with regard to concrete and abstract concepts can be accommodated best by hybrid theories of conceptual representation assuming an interaction between modality-specific, multimodal and amodal hub areas.