Processing of visual semantic information to concrete words: temporal dynamics and neural mechanisms indicated by event-related brain potentials

Abstract

Event-related brain potentials were used to study the retrieval of visual semantic information to concrete words, and to investigate possible structural overlap between visual object working memory and concreteness effects in word processing. Subjects performed an object working memory task that involved 5 s retention of simple 4-angled polygons (load 1), complex 10-angled polygons (load 2), and a no-load baseline condition. During the polygon retention interval subjects were presented with a lexical decision task to auditory presented concrete (imageable) and abstract (nonimageable) words, and pseudowords. ERP results are consistent with the use of object working memory for the visualisation of concrete words. Our data indicate a two-step processing model of visual semantics in which visual descriptive information of concrete words is first encoded in semantic memory (indicated by an anterior N400 and posterior occipital positivity), and is subsequently visualised via the network for object working memory (reflected by a left frontal positive slow wave and a bilateral occipital slow wave negativity). Results are discussed in the light of contemporary models of semantic memory.

Notes

This study was performed at the Department of Experimental and Work Psychology, University of Groningen, The Netherlands. At the time of the study, Hein T. van Schie, Albertus A. Wijers, Rogier B. Mars, and Jeroen S. Benjamins were affiliated with the Department of Experimental and Work Psychology, University of Groningen, The Netherlands; Laurie A. Stowe and Hein T. van Schie were affiliated with the Department of Linguistics, University of Groningen, The Netherlands. Hein T. van Schie is now at the Nijmegen Institute for Cognition and Information, Nijmegen University, The Netherlands. Rogier B. Mars is now at the FC Donders Centre for Cognitive Neuroimaging, Nijmegen, The Netherlands. Jeroen S. Benjamins is now at the Helmholtz Research Institute, University of Utrecht, The Netherlands. This research was supported by a grant from the Netherlands Organization for Scientific Research (NWO) awarded to L.A. Stowe for the Pioneer Project “The Neurological basis of language.”

Note that the list of neuropsychological theories discussed here is not meant to be exclusive (for a more complete overview, see Caramazza, 1998).

Note that Berti, Geissler, Lachmann, and Mecklinger (2000) interpreted the effect over the frontal lobe as a negative slow wave to less complex patterns, instead of a positive slow wave to more complex patterns.

Notice that these results are inconsistent with the dual coding theory (Paivio, 1991), which proposes that imagistic processes are lateralised to the right hemisphere.

Note that this effect was marginal, and was only observed when abstract imageable words were compared with abstract non-imageable words.

Handedness was assessed informally through verbal enquiry.

Artefacts were detected in 9.2% of all trials.

In the subsequent text we will refer to these as posterior or occipital sites.