Date of Degree

9-2015

Document Type

Dissertation

Degree Name

Ph.D.

Program

Speech-Language-Hearing Sciences

Advisor

Loraine K. Obler

Subject Categories

Cognitive Psychology | Linguistics

Keywords

Cognitive functions; Language and aging; On-line sentence processing; PP-attachment; Referential context; Syntactic ambiguity

Abstract

Twenty-four younger adults (20-35 years, mean: 25.88) and thirty-four older adults (65-79 years, mean: 71.82) read sentences via a word-by-word self-paced reading paradigm. Study 1 examined how older and young adults resolve sentences containing Noun Phrase (NP) and Verb Phrase (VP)-attached Prepositional Phrases (PPs) yielding temporary syntactic ambiguity, and which cognitive factors (working memory capacity, inhibition, shifting attention, alternating attention, and cognitive processing speed) contribute to temporary syntactic ambiguity resolution.

Study 2 was designed to investigate how both age groups utilize contextual information while resolving PP-attachment, and which cognitive functions play a role in the use of referential context during syntactic ambiguity resolution. Specifically, Study 2A examined the effect of the presence of context by comparing reading times of ambiguous NP-attached PP in a null context versus a NP-supporting 2-referent context. In addition, the study asked which cognitive functions contribute to the use of supporting referential context during processing of NP-attached PP. Study 2B investigated efficiency of context use through manipulation of syntactic ambiguity (ambiguous NP-attached PP vs. unambiguous unreduced relative clause [URC]) and referential context (NP-supporting 2-referent context vs. VP-supporting 1-referent context). Additionally, this study asked which cognitive functions are related to the ability to overcome conflicting and misleading referential context during processing of NP-attached PP.

Except for alternating attention skills, older adults performed worse on cognitive skills than younger adults, exhibiting smaller working memory capacity, poorer inhibition and shifting attention skills, and slower cognitive processing speed. Across studies, older adults required longer processing times than younger adults. Older adults' slower processing across studies was assumed to be related to their poorer inhibition and shifting attention skills.

In Study 1, older adults had more difficulty processing NP-attachment than VP-attachment, whereas younger adults had comparable processing skills between NP-attachment and VP-attachment. Among cognitive functions, shifting attention and inhibition skills were related to ability to resolve PP-attachment ambiguity. Comparable performance patterns between younger and older adults were observed in Studies 2A and 2B. In Study 2A, when NP-attachment was presented in a NP-supporting 2-referent context, both age groups performed faster than in the null context condition. In Study 2B, both age groups utilized the 2-referent context as efficiently as the 1-referent context. However, older adults showed sensitivity to syntactic ambiguity (ambiguous NP-attached PP vs. URC), which was not observed in younger adults. Alternating attention skills were linked to the use of supporting context (Study 2A), and inhibition skills were related to the ability to overcome conflicting context (Study 2B) during NP-attachment ambiguity resolution.

Cognitive decline in aging is known to yield detrimental effects in syntactic processing. The results of this dissertation suggest that older adults are affected by syntactic constraints more than younger adults. However, older adults utilize referential context when encountering PP-attachment ambiguity as efficiently as young adults. In terms of contribution of cognitive functions to syntactic ambiguity resolution, among various cognitive functions, following cognitive functions only have been previously tested and reported their effects: working memory capacity, shifting attention and inhibition in younger adults and only working memory capacity in older adults. When five different cognitive functions were tested, the results show different cognitive functions were linked to the ability to resolve PP-attachment ambiguity in null (e.g., shifting attention and inhibition), supporting (e.g., alternating attention), and conflicting contexts (e.g., inhibition) for both age groups.

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