Language and the brain
المؤلف:
Paul Warren
المصدر:
Introducing Psycholinguistics
الجزء والصفحة:
P231
2025-11-13
47
Language and the brain
Throughout this book, evidence for the representations and processes that form the subject matter of psycholinguistics has been taken from a number of areas of study. These have included the results of neurophysiological research that has investigated the areas of the brain that are involved in language processing. Since the primary purpose of this book is to introduce the reader to psycholinguistic issues of relevance to different levels or stages of language production and comprehension, this kind of evidence has been deliberately included alongside other sources of data, rather than in a separate chapter on language in the brain.
What, though, is the overall picture that has resulted from neurophysiological studies As one review has pointed out, this picture is far clearer for comprehension than for production (Salmelin, 2007). This is above all because of artefacts in the brain activity records that are caused by movements of the vocal apparatus for speaking. This is particularly the case for fMRI recordings, where movement of the head necessary for speaking of course can affect the recorded images (Zeffiro & Frymiare, 2006).
Unfortunately, it is not possible to get the same information about brain activity from covert speech, since it has been shown that different patterns of activity are associated with inner speech and actual spoken responses. Therefore, various types of comparison and normalisation are carried out to try to negate the effect of such other factors as head movement.
The general picture that emerges is that it is primarily the left hemi sphere that is involved and that the processes are very fast. For example, on the basis of a review of 82 neuroimaging studies of word production, Indefrey and Levelt (2004) set out the activation patterns shown in Figure 13.6 for picture naming. There is some temporal overlap between the processes, but activation is clearly localised to particular brain areas.
MEG data from studies of word recognition show equally fast processes. For example, spoken word recognition involves acoustic-phonetic feature activation some 50–100 msec after the onset of the speech sounds, phono logical analysis by 100–200 msec, and activation of lexical representations from about 200 msec onwards (Salmelin, 2007). Distinct activation pat terns for speech rather than non-speech emerge about 100 msec from the onset of the stimulus. In addition, syllables heard in a meaningful context result in similarly located but markedly different levels of activation from syllables in a non-meaningful context.
In silent reading, visual feature analysis occurs around 100 msec after the presentation of a stimulus, with letter-string analysis starting at about 150 msec. Letter-string analysis is much more heavily lateralised to the left hemisphere than general visual feature analysis.
الاكثر قراءة في Linguistics fields
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