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COVERT BEHAVIOR HAS POTENTIALLY GREAT SCIENTIFIC AND TECHNOLOGICAL IMPORTANCE, THOUGH PRESENT KNOWLEDGE OF THIS RESPONSE CLASS IS MEAGER. SCIENTIFICALLY, COVERT BEHAVIOR HAS BEEN STUDIED FOR TWO REASONS--(1) BECAUSE OF ITS INTIMATE RELATION TO THE "THOUGHT PROCESSES," AND (2) BECAUSE IT IS PART OF THE REALM OF BEHAVIOR THAT THE PSYCHOLOGIST SEEKS TO UNDERSTAND--A SCIENCE OF BEHAVIOR THAT CONFINED ITSELF TO OVERT RESPONSES WOULD BE, AT BEST, INCOMPLETE. THE BROAD PURPOSE OF THE RESEARCH REPORTED HERE IS TO INCREASE THE UNDERSTANDING OF THE NATURE AND FUNCTION OF COVERT BEHAVIOR. THIS REPORT CONSISTS OF SIX SECTIONS. THE PROBLEM FOR EACH SECTION IS DEVELOPED SEPARATELY, AS ARE THE METHODS OF ATTACKING EACH PROBLEM, THE RESULTANT FINDINGS, THE DISCUSSION, AND CONCLUSIONS. THE REPORT DOCUMENTS THE OCCURRENCE OF HEIGHTENED COVERT ORAL BEHAVIOR IN A VARIETY OF SITUATIONS, AND THE FINDINGS STRONGLY SUGGEST THAT THIS KIND OF BEHAVIOR IS BENEFICIAL TO THE INDIVIDUAL IN SOME WAY. THE RESULTS ARE ENCOURAGING AND FORM THE BASIS FOR A MORE SUBSTANTIAL ATTACK ON COVERT BEHAVIOR. TABLES, FIGURES, AND BIBLIOGRAPHIES ARE INCLUDED. (AUTHOR/BL)

This article is from PLoS ONE , volume 8 . Abstract Seeing the articulatory gestures of the speaker (“speech reading”) enhances speech perception especially in noisy conditions. Recent neuroimaging studies tentatively suggest that speech reading activates speech motor system, which then influences superior-posterior temporal lobe auditory areas via an efference copy. Here, nineteen healthy volunteers were presented with silent videoclips of a person articulating Finnish vowels /a/, /i/ (non-targets), and /o/ (targets) during event-related functional magnetic resonance imaging (fMRI). Speech reading significantly activated visual cortex, posterior fusiform gyrus (pFG), posterior superior temporal gyrus and sulcus (pSTG/S), and the speech motor areas, including premotor cortex, parts of the inferior (IFG) and middle (MFG) frontal gyri extending into frontal polar (FP) structures, somatosensory areas, and supramarginal gyrus (SMG). Structural equation modelling (SEM) of these data suggested that information flows first from extrastriate visual cortex to pFS, and from there, in parallel, to pSTG/S and MFG/FP. From pSTG/S information flow continues to IFG or SMG and eventually somatosensory areas. Feedback connectivity was estimated to run from MFG/FP to IFG, and pSTG/S. The direct functional connection from pFG to MFG/FP and feedback connection from MFG/FP to pSTG/S and IFG support the hypothesis of prefrontal speech motor areas influencing auditory speech processing in pSTG/S via an efference copy.