WORD, PHRASE AND SENTENCE 
Kob't F. Sinnnons 
Univ. of Texas, Austin 
Among the relative verities of natural language 
processing are the facts that morphemes and words are 
primary semantic units, and that their co-ocurrence in 
phrases and sentences provides cues for selecting sense 
meanings. In this session, two psycholinguistic 
studies show some aspects of how human subjects process 
words while reading. A study of medical vocabulary 
shows that medical words are highly associated by 
co-occurrance in medical definitions. Another report 
shews the effectiveness of keyword identification and 
selection of prominent sentences to organize abstracts 
for retrieval. 
A fifth study argues that analysis of existing natural 
language dictionaries can be expected to contribute 
importantly to what is needed for text understanding 
programs. The final study is an experiment with a 
sentence level translator applied to a large 
German-English translation task. These two studies are 
primarily concerned with analysis of language at the 
sentence level. 
The most glamourous areas of natural language research 
are at levels above the sentence, concerned with 
dialogues and discourse, frequently disdainful of 
morphological or even grammatical analysis in their 
search for effective structures for understanding what 
the discourse is about. Scripts, frames, stereotypes, 
schemas are all studied in these areas; and often 
morphological and gra~natical analysis is bypassed in 
favor of keyword scanning to extract some small 
relevant portion of the text to be bound as values for 
slots in these larger data forms. 
This session reminds us that much can be accomplished 
with vocabulary analysis, with keyword scanning and 
statistical treatment of text and with semantic 
analysis at the single sentence level. Yet, with 
regard to most of the topics in this and other 
sessions, there is a stronK sense of de~a vu; the 
earliest natural language studies featured automatic 
extracting and information retrieval based on 
statistical, lexical and associational properties of 
keywords. Mechanical translation of sentences without 
regard for larger contexts marked the late sixties high 
point of MT research amid contemporaneous studies of 
the English dictionary and thesaurus. Competition 
among sentence parsing algorithms is an ACL tradition 
celebrated annually, while psycholinguistics has 
traditionally applied chronometric studies, and 
recordings of eye movements to measure this or that 
aspect of human linguistic processing throughout the 
period. 
This is not to suggest that nothing new is happening; 
actually, the continued emphasis on these topics 
reveals that, though introduced early, they are still 
imperfectly understood. Z believe science progresses 
in spirals; initial studies are accomplished and 
published supporting more advanced studies that build 
upon the findings of the earlier work. Superstructures 
of theory are constructed and more work is undertaken 
in this framework. Finally the initial studies are 
lost in years of accumulated literature, and perhaps 
some of the wildest theories begin to collapse. Then 
the field may suddenly show renewed interest in its 
beginnings and repeat its early studies with the added 
sophistication gained by experience. At this time the 
line of history spirals past the points it reached on 
earlier cycles. Hopefully, as in this session, the 
experience gained between cycles insures an upward 
progression rather than a profitless loop. 
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