Merrill Garrett

Some syntactic determinants of sentential complexity

The perceptual complexity of three lists of self-embedded sentences was evaluated in terms of the accuracy and time required for their paraphrase. The lists differed by the presence of relative pronouns in one list, their absence in a second and by the addition of adjectives to the third. It was predicted that the presence of the relative pronouns would effect the only significant change in performance. In both auditory and visual presentations of the sentence lists, the presence of the relative pronouns proved to be facilitating, while the presence of the adjectives produced no significant changes.

The active use of grammar in speech perception

Judgments of the location of short bursts of noise in sentences were used to reveal perceptual segmentation of sentences. It was assumed that segmentation would correspond to major constituent boundaries. In order to control for correlated variables of pitch and intonation, identical acoustic material was provided with alternate constituent structures. It was found that differences in response to identical strings were predicted by the points of variation in constituent structure.

Lexical decision in sentences: effects of syntactic structure

A lexical decision paradigm was used to examine syntactic influence on word recognition in sentences. Initial fragments of sentences were presented visually (CRT display) one word at a time (at reading speeds), from left to right. The string terminated with the appearance of a lexical decision target. The grammatical structure of the incomplete sentence affected lexical decision reaction time (RT). In Experiment 1, modal verb contexts followed by main verb targets and preposition contexts followed by noun targets produced lower RTs than did the opposite pairings (i.e., modal/noun and preposition/verb). In Experiment 2, transitive verb contexts followed by noun targets and subject noun phrase contexts followed by verb targets yielded lower RTs than did the opposite pairings. Similar contrasts for adjective targets did not yield comparable effects in Experiment 2, but did when the adjective was the head of a predictable phrase (Experiment 4). In Experiment 3, noun targets yielded lower RTs than did verb targets after contexts of a transitive verb followed by a prepositional phrase. An account of these effects is offered in terms of parsing constraints on phrasal categories.

Some syntactic determinants of sentential complexity, II : Verb structure

The effect of the lexical complexity of verbs on the processing of sentences was evaluated in two experiments. Verb complexity was indexed by the number of types of grammatical structure a verb permits (e.g., a verb may be transitive or intransitive and may permit various types of complement structures). Ss’ performances in paraphrasing sentences and in solving anagrams containing complex verbs were significantly poorer than their performances with the same sentences and anagrams containing less complex verbs.

The interaction of perceptual processes and ambiguous sentences

General principles of speech perception resolve several experimental conflicts about whether listeners interpret one or all meanings of an ambiguous sentence We argue that during all ambiguous clause, both meanings are processed, but immediately after the clause over, it recoded with only one meaning retained This model resolves the apparently conflicting results of previous experimental, it also predicts that underlying structure ambiguity m incomplete clauses increases Comprehension time In complete clauses, ambiguity does not increase relative comprehension time; it mayreduce comprehension time for ambiguities whose interpretations are perceptually distinct in those tasks where either meaning is appropriate Two new experiments offer preliminary confirmation of these predictions

Hemisphere differences in the recognition of closed and open class words

The distinction between closed and open class words--of interest in the first instance because of claims about the support of structural analysis during comprehension--has its reflection in word recognition. For normal speakers, performances over these types give evidence of the operation of separate recognition devices, while for agrammatic speakers, performance indicates no such separation. A study of recognition accuracy with tachistoscopic presentation lateralized to the visual hemifields suggests some parallel between left and right hemisphere processing and the contrast of normal and agrammatic speakers: with direct input restricted to the left hemisphere, the vocabulary types show different levels of accuracy; no such differences are evident with presentations to the right.

Grammatical class effects in relation to normal and aphasic sentence processing

Agrammatic, Brocas aphasic patients, Wernickes aphasic patients, and neurologically intact control subjects were asked to detect target letters in prose passages and in a scrambled word passage. The targets were embedded, in some instances, in content words (open-class vocabulary items), and in other instances, in function words (closed-class vocabulary items). With respect to the prose passages, both the control subjects and Wernickes aphasic patients were more apt to notice target letters when they appeared in the open-class items than when in closed-class items; by contrast, the agrammatic Brocas patients showed no vocabulary class detection difference. The Wernickes patients were not entirely normal, however: Whereas the normal subjects showed a much smaller vocabulary class effect for letter detection in the scrambled condition, the Wernickes maintained the pattern they had shown in the prose condition. These and other findings obtained on the letter cancellation task are discussed in relation to lexical access mechanisms geared to sentence parsing.

Pi ka pu: The perception of speech sounds by prelinguistic infants

Experimentation with 14–18-week-old infants indicates that they are capable of grouping together syllables of English depending on whether the syllables share a consonant. These results indicate that infants may have access to the mechanisms that underlie certain perceptual constancies in adult speech perception.

Experimental Issues in Sentence Comprehension : Complexity and Segmentation

Questions about the order of processing events during speech perception are among the most interesting and challenging in the psychology of language. Relating segmentation strategies to computational effort appears to be a possible approach to a difficult area. If we knew where processing takes place and where it is held in abeyance, we would have some basis for inferring what kinds of information are needed by the recognition system for the projection of grammatical structures. Knowing what kinds of structures are, in fact, inferred by the hearer at given points in the sentence would help us to refine our guesses about the function of specific kinds of information (e.g., acoustic, phonetic, lexical, etc.).