A bilingual advantage for episodic memory in older adults

Abstract

The ability to remember events—referred to as episodic memory—is typically subject to decline in older adulthood. Episodic memory decline has been attributed in part to less successful executive functioning, which may hinder an older adult's ability to implement controlled encoding and retrieval processes. Since bilingual older adults often show more successful executive functioning than monolinguals, they may be better able to maintain episodic memory. To examine this hypothesis, we compared bilingual and monolingual older adults on a picture scene recall task (assessing episodic memory) and a Simon task (assessing executive functioning). Bilinguals exhibited better episodic memory than their monolingual peers, recalling significantly more items overall. Within the bilingual group, earlier second language acquisition and more years speaking two languages were associated with better recall. Bilinguals also demonstrated higher executive functioning, and there was evidence that level of executive functioning was related to memory performance. Results indicate that extensive practice controlling two languages may benefit episodic memory in older adults.

Keywords:

• Ageing
• Bilingualism
• Language
• Memory

Acknowledgments

The authors thank Anthony Shook, James Bartolotti, Sarah Chabal, Lucica Iordanescu, Jennifer Krizman, Natalia Daniel, Celia Berdes, Maria Hicks, Mara Mather, and Barbara Schroeder for their contributions to the current study. The project was funded by Grant NICHD 1R01HD059858 to VM and a Northwestern University School of Communication Graduate Research Ignition Grant to SRS.

Notes

¹An additional participant was tested but not included because of low proficiency in English, as revealed by a score more than 2.5 SDs below the mean on the English vocabulary task (PPVT-III) and a rating of 5 out of 10 on the LEAP-Q.

²The more proficient language was English for 4 bilingual participants, the non-English language for 13 bilingual participants, and neither for 1 bilingual participant whose two languages were equally proficient. The more-frequently used language at the time of testing was English for 13 bilingual participants, the non-English language for 4 bilingual participants, and neither for 1 participant who used both languages equally often.

³Due to time constraints, only a subset of participants completed valence ratings (14 monolinguals, 12 bilinguals) and arousal ratings (12 monolinguals, 9 bilinguals).

⁴The recall rates in the present study are similar to the recall rates reported in several previous studies on free recall of pictures in normal older adults (e.g., Berkman et al., 1993; Charles et al., 2003; Cherry et al., 2008; Lupien et al., 1998; Luszcz, Bryan, & Kent, 1997).

⁵Groups did not differ in how detailed their descriptions were, as measured by number of words per description and number of adjectives per description (ps>.1).

⁶In several previous studies, bilinguals displayed a smaller Simon effect and responded faster overall than monolinguals on Simon-type tasks. In the present study, bilinguals were not faster overall; in fact, they responded slightly but not significantly slower. Although at odds with some previous studies, the pattern of results reported here replicates that of two recent studies comparing bilingual and monolingual older adults on the Simon task (Bialystok et al., 2008; Salvatierra & Rosselli, 2011).

⁷The outliers removed in the Simon analyses (described in the Data Coding section) were also removed from the correlation analyses. No additional outliers were removed when computing the correlations.