Interaction Of Knowledge Sources Research Articles

The Interaction of Knowledge Sources in Word Sense Disambiguation

Word sense disambiguation (WSD) is a computational linguistics task likely to benefit from the tradition of combining different knowledge sources in articial intelligence research. An important step in the exploration of this hypothesis is to determine which linguistic knowledge sources are most useful and whether their combination leads to improved results. We present a sense tagger which uses several knowledge sources. Tested accuracy exceeds 94% on our evaluation corpus. Our system attempts to disambiguate all content words in running text rather than limiting itself to treating a restricted vocabulary of words. It is argued that this approach is more likely to assist the creation of practical systems.

Interaction of knowledge sources in spoken word identification

A gating technique was used in two studies of spoken word identification that investigated the relationship between the available acoustic-phonetic information in the speech signal and the context provided by meaningful and semantically anomalous sentences. The duration of intact spoken segments of target words and the location of these segments at the beginnings or endings of words in sentences were varied. The amount of signal duration required for word identification and the distribution of incorrect word responses were examined. Subjects were able to identify words in spoken sentences with only word-initial or only word-final acoustic-phonetic information. In meaningful sentences, less word-initial information was required to identify words than word-final information. Error analyses indicated that both acoustic-phonetic information and syntactic contextual knowledge interacted to generate the set of hypothesized word candidates used in identification. The results provide evidence that word identification is qualitatively different in meaningful sentences than in anomalous sentences or when words are presented in isolation: That is, word identification in sentences is an interactive process that makes use of several knowledge sources. In the presence of normal sentence context, the acoustic-phonetic information in the beginnings of words is particularly effective in facilitating rapid identification of words.

Priming the phonemic restoration illusion

When a portion of a spoken word is replaced by noise, listeners tend to perceptually restore the missing information. Recently, it has been shown that this phonemic restoration illusion is facilitated by the presentation of an intact version of a word prior to the same word with noise replacement [A. G. Samuel, J. Exptl. Psychol.: General 110, 474–494 (1981)]. The effects of this intact word prime on phonemic restoration may be attributed to either or both of two perceptual processes. One possible locus of this priming effect is phonemic encoding. The second possibility is the top‐down flow of information produced by lexical access. To dissociate the potential effects of phonological and lexical priming, the relationship between prime and test word was systematically varied. Subjects participated in: (1) a no prime condition, (2) a dissimilar word prime condition, (3) an identical word prime condition, and (4) a pseudoword prime condition in which the primes were phonologically matched to the test words. The interval between prime and test word was also varied. Signal‐detection analyses of the data provided separate measures of changes in discriminability and response bias across these conditions. The results have implications for theories of word recognition, lexical access, and the interaction of knowledge sources in spoken language understanding. [Work supported by grants from NIMH and NINCDS.]