Language Comprehension

Language comprehension is an important aspect of day to day functioning in adulthood. Comprehension of written and spoken language relies on the ability to correctly process word and phrase meanings, sentence grammar, and discourse or text structure. Difficulties in any of these domains can produce comprehension problems. Age-related memory declines have been reported in many studies comparing younger and older adults on language comprehension tasks. Therefore, it is believed memory capacity limitations in older adults may cause language comprehension problems (Wingfield and Stine-Morrow). In particular, age-related declines in the capacity of working memory to temporarily store linguistic information may be responsible for older adults' language comprehension problems. Older adults have typically been found to have smaller working memory spans than young adults and such span measures have been found to correlate with language comprehension measures. Van der Linden, and colleagues (1999) tested young and older adults on their ability to understand texts and recall sentences and words. They were also given a large battery of tests designed to measure processing speed, working memory capacity, and the ability to inhibit distracting thoughts. The analysis indicated that these three general factors (speed, working memory, inhibition) did account for age-differences in performance on the language processing tasks. Further, Van der Linden, and others concluded that "age-related differences in language, memory and comprehension were explained by a reduction of the capacity of working memory, which was itself influenced by reduction of speed, [and] increasing sensitivity to interference. . ." (p. 48).

Interference arising from a breakdown of inhibitory mechanisms appears to contribute to language comprehension problems (Hasher, Zacks, and May) by permitting the intrusion of irrelevant thoughts, personal preoccupations, and idiosyncratic associations. These irrelevant thoughts compete for processing resources, such as working memory capacity, and impair older adults' comprehension and recall. Hence, older adults' comprehension may be affected by distractions or intrusive thoughts. This hypothesis received support from a study by Kwong See and Ryan. Kwong See and Ryan examined individual differences in text processing attributable to working memory capacity, processing speed, and efficiency of inhibitory processes. Their analysis suggested that older adults' text processing difficulties can be attributed to slower processing and less efficient inhibition, rather than to working memory limitations.

Research by Connelly, Hasher, and Zacks compared passage reading times and answers to probe comprehension questions for young and older adults for texts that did or did not have distracting material interspersed amid target texts. The distractors, presented in a different type face, consisted of words or phrases conceptually related to the content of the target text and recurred over and over again throughout the target text. Connelly et al. reported that young adults not only read the texts containing the distracting material more rapidly than older adults but that they also showed greater comprehension of the target material. Connelly and colleagues' conclusion has been challenged by Dywan and Murphy who modified the procedure to include a surprise word recognition test for the interposed material. They found that the young adults had superior recognition memory for the distractor words, a result that is difficult to explain if the young adults are assumed to have been successful at inhibiting processing of the distractors. Burke also argues that research on the activation of word meanings and the detection of ambiguity provides "no support" for claims that "older adults are deficient in suppressing contextually irrelevant meaning or that they activate more irrelevant semantic information than young adults or that they retrieve more high frequency, dominant, or typical information than young adults" (p. P257).

Strategy differences may also underlie other age differences in language comprehension by affecting how readers process individual words. In general, young and older adults have been found to use similar reading strategies; however, age differences in reading strategies have been reported for specific aspects of syntactic and semantic processing. Stine found that young and older adults allocate reading time in similar ways to word-level and phrase-level processing. However, she also found young adults spent extra time reading words that occurred at sentence boundaries, minor clause boundaries, and major clause boundaries. While older adults also allocated extra time to major and minor clause boundaries, they did not spend extra time at sentence boundaries, suggesting older adults spend less time on sentence-level integration than young adults. Stine-Morrow, Loveless, and Soederberg (1996) let young and older adults read syntactically coherent text at their own pace. Both young and older adults who achieved good recall allocated extra reading time to syntactically complex sentences. However, some age differences were found with regard to other time allocation strategies used to achieve good recall. For young adults, good recall was related to the allocation of additional reading time to infrequent words and to new concepts first mentioned in the text. In contrast, for older adults, good recall was related to the allocation of additional reading time as they progressed serially through the text. These findings indicate that older adults use a different strategy than young adults to achieve good recall. Whereas young adults rely on recalling key words and concepts, older adults may rely on recalling a global text structure that is built up serially.

Despite working memory limitations, inhibitory deficits, and strategy differences, many older adults comprehend spoken and written language proficiently in everyday life. The age-related deficits observed in language comprehension studies may be offset by the ability to fill in missing elements of the discourse with meaningful reconstructions based on background knowledge and everyday reasoning abilities. Speakers and writers may also be able to minimize comprehension problems by using a special speech register, sometimes termed elderspeak. Elderspeak uses exaggerated pitch and intonation, simplified grammar, limited vocabulary, and slow rate of delivery. However, the use of elderspeak is controversial. On one hand, elder-speak may benefit older adults by reducing memory and processing demands. On the other hand, it may reinforce negative stereotypes of older adults and contribute to the social isolation and cognitive decline of older adults because it resembles "baby talk." Addressing older adults in "baby talk" by using short, simple sentences delivered very slowly and loudly with contrastive pitch seems to convey the impression to older adults that they are cognitively impaired and have communication problems (Kemper and Harden). Hence, practical techniques for modifying speech and writing targeted at older adults must reduce processing demands without triggering negative stereotypes.