The effect of ageing and encoding instructions on episodic memory

During ageing, a decline in episodic memory is observed, characterized by decreased recollection (a). In this study, we investigated the influence of encoding instructions, intentional or incidental, on the performance of younger and older adults during an episodic memory task.
Twenty young volunteers (aged 18 to 30 years old) and 20 older volunteers (aged 61 to 72 years old) participated in this experiment. The stimuli consisted of 300 black-and-white drawings of common objects. The task comprised two steps. During the encoding phase, 100 items were presented once ("hard" condition) and 100 other items were presented twice ("easy" condition). During recognition, the items from the encoding phase were presented again, as well as 100 new items. In each age group, half of the participants received incidental encoding instructions (they had to make size judgements about the objects depicted) while the other half were explicitly asked to memorize the objects presented because they would be asked to recognize them later on (intentional encoding). During recognition, they performed a Remember-Know judgement for the items they believed they had seen earlier. We carried out ANOVAs in order to test for the influence of instructions, age group and number of repetitions of the items in one hand on the percentage of recollection and on the other hand on the percentage of familiarity (p<.05).
Results show a significant effect of age, with more correct recollection responses in young adults, whereas more correct familiarity was found in older adults. Furthermore, it was found that the items presented twice lead to more recollection than those presented only once. Finally, these results also suggest that in the older group of participants, only for the items presented twice, intentional encoding instructions lead to more recollection and less familiarity. This finding is consistent with previous work showing that the elderly do not easily use elaborate encoding strategies, and that they need more support (here, a second exposition to the material) in order to perform a deep encoding when they are encouraged to do so with intentional learning instructions (b).
(a) Bugaiska, A., Clarys, D., Jarry, C., Taconnat, L., Tapia, G., Vanneste, S., & Isingrini, M. (2007). The effect of aging in recollective experience: the processing speed and executive functioning hypothesis.
Consciousness and Cognition, 16(4), 797-808. doi: 10.1016/j.concog.2006.11.007
(b) Froger, C., Bouazzaoui, B., Isingrini, M., & Taconnat, L. (2012). Study time allocation deficit of older adults: the role of environmental support at encoding? Psychology and Aging, 27(3), 577-588. doi:10.1037/a0026358