Subjective and objective spatial memory and navigation abilities in aging and amnesia

Compared to the extensive research on how older adults evaluate their memory abilities, the evaluation of subjective spatial navigation abilities is understudied. This dissertation was guided by four research objectives: 1) Investigate the psychometric properties of a subjective spatial navigation questionnaire to assess the nature and extent of self-reported changes to spatial navigation in neurotypical aging; 2) Determine the relationship among subjective assessments of spatial navigation and of memory and how they relate to psychological distress and objective memory performance; 3) Understand the impact of hippocampal damage on subjective awareness of areas of spared and impaired episodic and spatial memory; and 4) Identify more precisely the conditions in which spatial memory and navigation depend on hippocampal integrity. In study 1, multidimensional item response theory was used to evaluate the factor structure and item reliability of the novel Changes in Navigation Questionnaire (CNQ) in a community sample of older adults. Results showed that the CNQ has a reliable factor structure, with items falling under typical and atypical changes. In study 2, the relationship between subjective spatial navigation and metamemory in aging was investigated using structural equation modeling. Findings showed that the subjective spatial navigation and metamemory constructs had a positive, weak correlation. Objective episodic memory performance did not load onto metamemory, and allocentric spatial memory performance had a weak loading onto spatial navigation abilities. Psychological distress symptoms had stronger loadings on metamemory than spatial navigation abilities. In study 3, two individuals with hippocampal amnesia completed questionnaires assessing metamemory and spatial navigation abilities and were compared to age-, gender-, and education-matched controls. The individuals with amnesia reported sound awareness of metamemory and spatial navigation difficulties. Lastly, in study 4, these individuals’ performance on a videogame wayfinding measure was compared with that of thousands of well-matched controls. The individuals showed distinct patterns of impairment and preservation on the tasks. These dissertation results show that subjective spatial navigation abilities can be reliably captured with questionnaires, are weakly related to metamemory, and that accurate self-evaluation is not contingent on intact episodic memory. The findings also highlight specific aspects of navigation that are hippocampal dependent.