Why do older adults have difficulty with semantic fluency?

ABSTRACT

Aging involves many cognitive declines, particularly in fluid intelligence, with relative maintenance of crystallized intelligence. This paradox is evident in the language domain: lexical retrieval becomes slower and less accurate, despite well preserved vocabularies. Verbal fluency assesses both crystallized and fluid aspects of language. Semantic fluency hypothetically reflects semantic knowledge, while letter fluency putatively reflects executive functioning, which would predict a greater impact of aging on the latter. However, the opposite is typically observed.

To investigate factors contributing to such asymmetries, we examined verbal fluency in 86 adults (30-89 years). Multiple regression analyses indicated that semantic fluency depends largely on lexical retrieval speed, as well as visualization strategies to support controlled retrieval, skills which may disproportionately decline with age. By contrast, letter fluency relies heavily on vocabulary knowledge, providing some protection against age-related declines. These findings contribute to our understanding of the mechanisms of typical age-related declines in word retrieval.

KEYWORDS:

• Aging
• lexical access
• word retrieval
• verbal fluency
• vocabulary

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. For further details on the naming protocol, please see Gordon and Kurczek (2014). Naming data from 15 of the subjects in that study are also analyzed in the current study, although the previous study included data from the 200 single-syllable targets only. Naming, vocabulary, and verbal fluency data from a subset of these subjects were also analyzed by Gordon and Kindred (2011).

2. Although so-called “task-discrepant” clusters (e.g., semantic clusters in letter fluency tasks) can also be counted and were observed in the current study, we did not include them in the analyses of the current study.

3. Thanks to an anonymous reviewer for bringing up this possibility. In re-reviewing the literature, we noted that many, if not most, studies neglect to report the order of the tasks, even when directly comparing performance across tasks. This should be remedied in future studies in order to account for possible fatigue or practice effects.

Additional information

Funding

This research was supported by a grant to the first author from the University of Chicago’s Defining Wisdom Project and the John Templeton Foundation.