Influence of the linguistic system on perception
المؤلف:
Paul Warren
المصدر:
Introducing Psycholinguistics
الجزء والصفحة:
P113
2025-11-05
23
Influence of the linguistic system on perception
There are many ways in which our perception is influenced by the linguistic system, i.e. by the fact that the sounds or visual shapes we are processing might be considered part of language. We saw evidence of this earlier p. 105 where phoneme restoration effects depended on the sentence context in which the replaced phoneme occurred. We see it also in the perceptual advantages that language-relevant stimuli have. For example, studies in which sounds are embedded in noise have shown that speech sounds are more reliably identified or recalled than non-speech sounds. On top of this, if the speech sounds make up real words rather than nonsense, then they have an even greater processing advantage. Neurophysiological studies, using EEG and MEG to measure electrical activity in the brain, show that this processing advantage for real words over nonsense words becomes distinct as early as 150 msec after the point at which a word can be recognised (Pulvermller et al, 2001). The fact that this is a linguistic effect rather than a consequence of differences in the sounds involved is shown by the fact this is found for native speakers of the language being tested Finnish in this case but not for foreigners who do not know the language.
A very significant area in which a linguistic influence on speech perception has been demonstrated is categorical perception. Work in this area dates back to the 1950s Liberman, Harris, Hoffman Griffith, 1957, but our understanding of what is involved in categorical perception has been refined over the intervening decades. As the name suggests, categorical perception relates to the finding that we hear speech sounds as belonging to categories. That is, if we are presented with a series of speech stimuli that vary along some linguistically relevant phonetic dimension, then we will classify some of them as belonging to category X and some as belonging to category Y, rather than hearing a particular stimulus as being X-ish, another as being a little more Y-like, and so on.
Although categorical perception has been demonstrated for a range of contrasts, the one most widely cited is the distinction between voiced and voiceless plosive consonants, e.g. between /b/ and /p/. This distinction is actually signalled by a range of different parameters, but the one that has usually been explored is Voice onset time (VOT). Voice onset time is the lag between the release of the closure for the plosive consonant in this case the opening of the lips and the beginning of voicing for a following vowel. This is shorter for a voiced plosive like /b/ than for a voiceless one like /p/ – in English typically less than and more than 30 msec respectively.
In experiments, participants are given synthesised /ba/-like or /pa/-like syllables to respond to. The response can either be an identification one is this /ba/ or /pa/ or a discrimination one are two stimuli the same or different . The identification responses show that rather than there being a gradual change of responses from /ba/ to /pa/ as VOT increases, there is a dramatic switch of response preference part-way along the con tinuum. In terms of the hypothetical responses shown in Figure 7.6, responses to VOT continua follow a categorical function – also referred to as an S-curve because of the shape of the line in such a figure – rather than a smooth or straight-line function.
Responses in the discrimination tasks show that participants treat as same’ two stimuli that fall on the same side of the dramatic shift in the identification response, e.g. in terms of Figure 7.6, stimuli 2 and 3, or 3 and 4, or 5 and 6, but will label as different’ two stimuli that fall on either side of the shift, i.e. stimuli 4 and 5 in the figure. They do this even if in terms of VOT the difference between 4 and 5 is of the same magnitude as the difference between 3 and 4 or between 5 and 6. This is evidence that sounds are placed into perceptual categories, with rather sharp boundaries between the categories. These findings have been supported by neurophysiological studies that have demonstrated different brain responses measured through changes in event-related magnetic fields, or ERFs to tokens either side of a category boundary, but similar responses to stimuli within a VOT category e.g. Simos e al., 1998.
Categorical perception makes sense from the point of view of language perception and comprehension. This is because we expect spoken sound to indicate linguistic entities as part of the comprehension process.
الاكثر قراءة في Linguistics fields
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