Odor and source remembering in adulthood and aging : Influences of semantic activation and item richness

Larsson, M. Odor and source remembering in adulthood and aging: Influences of semantic activation and item richness. Doctoral Dissertation, Department of Clinical Neuroscience and Family Medicine, Division of Geriatric Medicine, Karolinska Institute; and Stockholm Gerontology Research Center, Section of Psychology. Correspondence: Stockholm Gerontology Research Center, Box 6401, S-113 82 Stockholm, Sweden. e-mail: maria.larsson@cnsf.ki. se.1996; ISBN 91-628-2324-8. The overall aim of this doctoral thesis was to investigate episodic memory in early and late adulthood. Of particular interest was to examine whether older adults could make use of different forms of cognitive support in order to improve episodic memory performance. In addition to traditional assessments of item memory, memory for source and olfactory information were assessed. Manipulations of the level of cognitive support included experimenter-provided guidance at encoding (i.e., organizational instructions, a blocked presentation format, activation of prior knowledge), the degree of salience in the materials (e.g., words, objects, odors), and the presence of cues provided at retrieval (e.g., category cues, copy cues). Furthermore, the importance of various subject-related factors (i.e., proficiency in semantic memory) as related to episodic odor recognition was examined. Study I focused on recall performance as a function of age, item richness, and experimenter-provided support at encoding and retrieval. Study II and III examined item memory and source memory for externally derived information differing in degree of salience and modalities engaged at acquisition. Of particular interest here was to investigate whether elderly adults are selectively penalized in source memory tasks relative to item memory tasks. In Study III, IV, and V episodic recognition memory for common odors as a function of age and time of testing (immediately and 48 hours after study) were examined. In addition, the relationship between various semantic memory functions and episodic odor recognition was examined in Study V. In general, the results across Studies I-IV indicate that the ability to utilize the forms of support examined is well preserved in old age. However, there was little evidence for selective improvement of memory from cognitive support in either old or young adults. Also, the degree of richness inherent in the information to-be-remembered was positively related to memory performance across studies. Materials which were rich in features were better remembered than were materials low in detail. Furthermore, when retrieval support was provided in the form of category cues, elderly adults could use this additional information to enhance their memory performance. Both item memory and memory for source decreased as a function of age, but older adults exhibited greater difficulties in specifying the source of information as compared with memory for the item itself. This was particularly true for olfactory information. Odor recognition memory decreased as a function of age and time. This drop in performance across time was independent of age. Moreover, specific odor knowledge, such as perceived familiarity and identifiability, was strongly and positively related to performance in episodic odor recognition, whereas more general aspects of semantic memory were not associated with odor memory. Most important, accessibility of odor names was critical to episodic odor recognition in general, and mediated completely age-related deficits in odor recognition.