Introduction to Cognitive Psychology - Department of Psychological ...

Professor Greg Francis 1/2/13ParsingTwo problemsOnce every slot is filled, the sentence isparsed a mental click of understandingEach word has its role definedParsing is complicated in two ways (1) Phrases are not always consistent with word order (2) The same spoken sounds are sometimes used forwords with different meanings (noun vs verb vsadjective) and the order of the phrases identifies themeaning (usually)Purdue UniversityPurdue UniversityWord orderWord orderThis sentence is relatively easy to parse,even though it is a complicated sentenceThis sentence is not as easyOne type of phrase is embedded in anotherSPP PP PPRemarkable is the rapidity of the motion of the wing of the hummingbird.SPPThe rapidity that the motion has is remarkable.Purdue UniversityPurdue UniversityWord orderThis sentence is nearly impossibleS PP PP PPThe rapidity that the motion that the wing that the hummingbird has has has is remarkable.Purdue UniversityDifficult sentencesThese sentences are difficult for humans because oflimited memory when a phrase tree includes many unfilled branches of thesame type (PP) the parser becomes confused as to which phrase isassociated with a new word ends up backtracking to sort out the phrases sometimes falls apart (has has has)The grammar generator and the parser are differentthings in your language system these are grammatically correct sentences they are not good sentencesDont you make sentences like thesemake meshow youyour exams!Purdue UniversityPSY 200: Intro. to Cognitive Psychology 3