How Continuous Concreteness Shapes Brain Processing and Concept
Representation Across Diverse Tasks: Insights from an ERP Study
Abstract
Behavioural research over several decades has found that concrete words
are processed more quickly and accurately than abstract words
(concreteness effect). This advantage is also reflected in their
different processing and representation in the human brain. In this
electrophysiological study, we explored the interplay of concreteness as
a continuous measure and task effects on word processing.
Electrophysiological responses of 58 participants were recorded during
semantic, affective, and grammatical decision tasks on words
parametrically varied in concreteness. Our findings uncovered a
fine-grained concreteness effect within four distinct spatiotemporal
windows when a coding of semantic information is required. In the
semantic decision task, we detected a higher parietal positivity within
the P300 time range and an increased left temporo-lateral negative-going
amplitude for less concrete concepts. We also identified a concreteness
effect characterised by greater negativity in the N400 component. In the
affective task, we observed a more pronounced parietal P600-like
component for more abstract concepts. Interestingly, we found that the
neural representational similarity (starting from 450 ms with a
widespread scalp distribution) conformed to the concreteness similarity
among concepts (regardless of the task), implying that their semantic
representations may be characterised along the concreteness dimension in
the brain. Our study transcends the conventional dichotomy of abstract
versus concrete words, unearthing not only varied processing dynamics
along the concreteness dimension but also distinct fine-grained neural
representations. This novel insight positions concreteness as a
structural dimension, enriching our comprehension of how the brain
organises and processes semantic information.