title: Lateralized electrical brain activity reveals covert attention allocation during speaking.
abstract: Speakers usually begin to speak while only part of the utterance has been planned. Earlier work has shown that speech planning processes are reflected in speakers' eye movements as they describe visually presented objects. However, to-be-named objects can be processed to some extent before they have been fixated upon, presumably because attention can be allocated to objects covertly, without moving the eyes. The present study investigated whether EEG could track speakers' covert attention allocation as they produced short utterances to describe pairs of objects (e.g., "dog and chair"). The processing difficulty of each object was varied by presenting it in upright orientation (easy) or in upside down orientation (difficult). Background squares flickered at different frequencies in order to elicit steady-state visual evoked potentials (SSVEPs). The N2pc component, associated with the focusing of attention on an item, was detectable not only prior to speech onset, but also during speaking. The time course of the N2pc showed that attention shifted to each object in the order of mention prior to speech onset. Furthermore, greater processing difficulty increased the time speakers spent attending to each object. This demonstrates that the N2pc can track covert attention allocation in a naming task. In addition, an effect of processing difficulty at around 200-350ms after stimulus onset revealed early attention allocation to the second to-be-named object. The flickering backgrounds elicited SSVEPs, but SSVEP amplitude was not influenced by processing difficulty. These results help complete the picture of the coordination of visual information uptake and motor output during speaking.
authors.affiliation: Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands; Department of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. Electronic address: jrommers@illinois.edu.
authors.forename: Joost
authors.initials: J
authors.lastname: Rommers
authors.affiliation: Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands; Donders Institute for Brain, Cognition, and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.
authors.forename: Antje S
authors.initials: AS
authors.lastname: Meyer
authors.affiliation: Department of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Donders Institute for Brain, Cognition, and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Praamstra
mesh_terms: D000293:Adolescent; D001288:Attention / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography; D005074:Evoked Potentials, Visual; D053483:Eye Movement Measurements; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D013060:Speech / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Covert attention; EEG; Language production; N2pc; Object naming