Episodic Memory in Adult Age and Effects of Sibship Size and Birth Order: Longitudinal Data

Abstract

This study examined the effects of sibship size and birth order on episodic memory performance in adulthood and old age. Participants were 1,141 healthy individuals aged 35-80 years, who took part in a longitudinal project on age, health, and memory. Episodic memory measurements over a 5-year interval included tests of recognition (recognition of faces, family names, first names, and nouns) and tests of recall (free recall of sentences, free recall and cued recall of nouns, and recall of activities). Results showed significant effects for both recall and recognition, that is, the smaller the sibship size is for an individual and the earlier born, the better memory performance. These results demonstrate that the effects of sibship size and birth order previously shown in children and adolescents (Belmont and Marolla, Science 182: 1096-1101, 1973 Zajonc and Markus, Psych Rev 82:74-88, 1975; Zajonc, Am Psychol 56:490-496, 2001) are robust over time and hold over a large adult range.Keywords Sibship size Á Birth order Á Episodic memory Á Adulthood and old age In a recent study, Holmgren et al. (2006) demonstrated that performance in tasks assessing intelligence and executive functions varied as a function of sibship size and birth order. The smaller the sibship size was and the earlier a person was born in his/her sibship, the better was the performance in the two domains of cognitive tasks.This finding is not new. A large amount of data has demonstrated that sibship size and birth order do affect intelligence in childhood and adolescence (e.g., Belmont and Marolla

Sibship Size, Sibling Cognitive Sensitivity, and Children’s Receptive Vocabulary

“…18 A negative relationship between sibship size and measures of children' s attainment has been demonstrated, 15,16,19,20 which appears to persist into adulthood. [21][22][23] Additionally, later-born children show poorer vocabulary skills in comparison with firstborn children. 24,25 The negative effect of sibship size persists after accounting for the effect of socioeconomic status, 15,19 indicating that the association between socioeconomic status and sibship size does not account for the association between sibship size and educational attainment.…”