Aging and Language Processing – Lecture 6

PS 277

Outline

Language as a System

Theories of Aging and Language Processing (Burke, 2008)

Research on Aging and Types of Language Processing

Syntax Comprehension and Production

General Model of Language System and Processing Comprehension vs. Production

Phonology/Orthography – mapping sounds and letters (K..a..tuh = cat)

Semantics – mapping words and meanings (cat, mouse, chase)

Syntax – composing sentences and using grammatical rules to mark appropriately (e.g., passive: The mouse (was chased) by the cat)

Discourse – extended texts and stories (Ch. 7)

Speech Comprehension – Far Side

Speed of Processing Theories and Language Aging is associated with slower processing

times

May be that component operations are too slow to execute before representations disappear (e.g., sentence comprehension needs several words to be activated simultaneously to understand meaning)

Some disagreement on how general vs. specific slowing is – does it affect language in same way as other cognitive processes?

Working Memory Deficits and Aging

Working Memory: storing and manipulating items of information – e.g., backward digit span (DO)

Aging may be associated with less “space” in working memory, where active processing of language takes place

Transmission Deficit Theory and Language Processing Aging is associated with weakening of

connections in the brain and nervous system

Effect of this is to make information less likely to be transmitted accurately through the language system in older adults, leading to more errors

Similar to the “neural noise” models we discussed earlier for attention

Degraded Signal Theory and Language Processing Input from sensory systems gradually

becomes poorer as people age (Lindenberger & Baltes)

This degrades the signal, leads to more errors in initial mapping

If this is explanation, performance should be same across age groups if accuracy of initial language perception is equated

Language Research: Speech Comprehension – Phonology Mapping incoming sounds onto specific

phonemes, elements of word pronunciation

Older adults may have sensory deficits that make it harder to do this mapping from incoming signals to perceptual system

Even with these equated across age, older adults do worse when speech is degraded or distorted in some way. Loss of cues in the signal can be more problematic for older adults, even with technology aids

Semantic Comprehension

Taking words and symbols, mapping them onto concepts in a meaning network

Older adults generally do well here – e.g., good on vocabulary tasks until very late in life

Semantic priming and lexical decision tasks (deciding whether something is a word or not) are equivalent by age group: “nurse” primes recognition of “doctor” as a word faster than an unrelated word like “juice” primes “doctor” for both young and older adults = implicit memory

Syntax Comprehension and the Garden Path Must be able to hold multiple interpretations in mind

when processing text, especially complex sentences

“While Anna dressed the baby sat on the bed.”

Did Anna dress the baby?

Several angry workers warned about the low wages… (during the Christmas holidays). (decided to file complaints). (garden path version)

People routinely treat the first verb as the main verb of the sentence… go back and reinterpret “garden path” versions

Aging, Working Memory and Sentence Interpretation Older adults show some decline in working

memory measures on average

Kemper and others have shown that lower WM linked to comprehension problems with challenging syntax, using eye fixation studies in reading

Older adults with lower WM spans tend to spend more time going back to earlier clauses and understand more poorly

Aging and Garden Path Sentence Interpretations (Christianson et al.)

Correlations of Working Memory Span and Correct Interpretation

Syntax Production and Aging Syntactic complexity of speech production and

written language declines with age (Kemper, 2006)

Comprehension and production of “left-branching” sentences is tough: “The woman who runs a nursery school for our church is awfully young.” = Embedded constructions (NP + VP)

Nun Study showed important prediction from complexity of early written language to later cognitive aging

Example Autobiographies from Nun Study (Kemper) Sister Helen: “I was born in Eau Claire, Wisconsin on May 24,

1913 and was baptized in St. James Church. There are ten children in the family, six boys and four girls. Two of the boys are dead...”

Sister Emma: “It was about a half hour before midnight between February 28 and 29th of the leap year 1912 when I began to live and die as the third child of my mother, whose maiden name is Hilda Hoffman, and my father, Otto Schmitt. Already two, a brother and a sister, had begun the family which would gradually reach the number of eight…When I was in the 4th grade, death visited our family, taking one to whom I was very particularly attached, my little brother Karl, who was but a year and a half old…The pastor was willing to have the funeral before Easter, but I was hoping and praying that my parents would not consent, for I thought that since he died on Good Friday he might be in our midst, living, on Easter Sunday…”

Evidence from the Nun Study

Autobiographies collected from 93 nuns in 1930’s, when in their 20’s

Rated by Kemper and others for grammatical complexity

Follow-up in 1990’s – given yearly mental state exams, later diagnosis of Alzheimer’s and dementia outcomes at autopsy

35% of those with low density autobiographical stories had mental impairment; 2% of those with high density had impairment

Susan Kemper