Automatizität und Plastizität von konzeptuellen Repräsentationen
Zusammenfassung der Projektergebnisse
Conceptual representations in human semantic long-term memory play an important role for our language, action and thought. They constitute the meaning of our words and provide the cognitive basis for our knowledge of the world. The organization of this knowledge in semantic memory, however, is controversially discussed: Classical views postulate a unitary amodal system totally distinct from the sensory and motor brain regions, where concepts are represented in a symbolic and abstract fashion. The more recent modality-specific theory, instead, assumes that concepts are represented in the sensory and motor brain systems, which are also active during perception and action (embodiment). In the present project, modalityspecific theory was further tested by assessing functional and anatomical characteristics of the conceptual representations of action- and sound-related concepts (nouns and verbs). In 19 experiments, the precise functional-anatomical localization, the automaticity and causality of activity in the sensory-motor brain systems during conceptual processing as well as plastic changes in conceptual processing in deaf individuals were investigated by functional imaging, event-related brain potential recordings and behavioral measurements. Unexpectedly, in the first experiment the feature-specific effects were primarily related to nouns and less to verbs. We assumed that the long and thus straining experimental session (more than 1 hour) reduced participants’ attention to the stimuli. This had a greater impact on the effects for verbs, because in verbs (e.g., drumming and cheering) differential relevance of action- and sound-related conceptual features was less pronounced compared with nouns. Therefore, we decided to study featurespecific representations of nouns and verbs separately in the course of the project to reduce the length of the experimental sessions. A functional magnetic resonance imaging study confirmed separate conceptual representations of action- and sound-related words in or close to corresponding modality-specific areas in posterior middle temporal gyrus. Five studies using event-related potential recordings revealed distinct brain circuits for action- and sound-related concepts. Three of those EEG studies used variants of a masked priming paradigm demonstrating that these modality-specific cortical structures are also activated unconsciously and thus automatically thereby excluding any contribution of strategic imagery processes. Furthermore, detailed assessment of patient JR and action priming studies revealed a functional relevance of auditory and visuo-motor areas for conceptual processing of sound and action, respectively. Finally, in line with modality-specific theories we showed that conceptual processing is strongly experience-driven. The missing auditory modality in deaf individuals leads to a greater reliance on visual and motor information compared to hearing individuals. In deaf individuals, we also found evidence for a stronger contribution of the language system in conceptual processing that complements representations in the modality-specific sensory and motor systems. Overall, these findings substantiate the significance of the sensory and motor brain systems for conceptual processing and provides further important evidence for a grounding of concepts in perception and action in an experience-dependent fashion. The notion of grounding of conceptual knowledge is highly relevant for improving education, but also for marketing and corporate communications. Our research was featured in TV, radio, magazine and newspaper reports.
Projektbezogene Publikationen (Auswahl)
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(2012). Conceptual representations in mind and brain: Theoretical developments, current evidence and future directions. Cortex, 48, 805-825
Kiefer, M., & Pulvermüller, F.
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(2012). Dissociating the representation of action- and sound-related concepts in middle temporal cortex. Brain and Language, 122, 120-125
Kiefer, M., Trumpp, N. M., Herrnberger, B., Sim, E.-J., Hoenig, K., & Pulvermüller, F.
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(2013). Losing the sound of concepts: Damage to auditory association cortex impairs the processing of sound-related concepts. Cortex, 49, 474-486
Trumpp, N. M., Kliese, D., Hoenig, K., Haarmaier, T., & Kiefer, M.
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(2013). Masked priming of conceptual features reveals differential brain activation during unconscious access to conceptual action and sound information. PLoS ONE 8(5): e65910
Trumpp, N. M., Traub, F., & Kiefer, M.
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(2014). Unconscious automatic brain activation of acoustic and action-related conceptual features during masked repetition priming. Journal of Cognitive Neuroscience, 26, 352-364
Trumpp, N. M., Traub, F., Pulvermüller, F., & Kiefer, M.
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(2014). When action observation facilitates visual perception: Activation in visuo-motor areas contributes to object recognition. Cerebral Cortex
Sim, E. J., Helbig, H. B., Graf, M., & Kiefer, M.
