Numerical cognition in ageing : investigating the impact of cognitive ageing on foundational non-symbolic and symbolic numerical abilities
Norris, Jade Eloise
Thesis or dissertation
- © 2015 Jade Eloise Norris. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.
Healthy ageing is associated with a gradual decline in several cognitive functions, including processing speed, inhibitory control, memory, executive functions, and problem solving. However, the trajectory of ability in numerical cognition in older age remains unclear. Some research investigating exact skills such as arithmetical problem solving have found declined numerical abilities in older age due to reduced access to effective strategies. However, other research has indicated stable or even enhanced mathematical and arithmetical abilities in older age. Furthermore, limited research is available on the impact of ageing on foundational numerical abilities. The effect of cognitive ageing on such foundational abilities poses an interesting question due to the innate, evolutionary nature of foundational numerical skills. It is possible that such automatic, innate and primitive abilities may be spared in ageing, alongside emotional processing, autobiographical memory, and vocabulary and verbal skills.
Available studies investigating basic numerical abilities in ageing present contradictory results and methodological variation. Furthermore, although a limited number of studies have investigated foundational non-symbolic abilities in ageing, the effect of older age on foundational symbolic abilities is yet to be directly tested. The thesis therefore explicitly investigated the impact of healthy ageing on foundational non-symbolic and symbolic numerical processing with a series of experiments. Chapter 2 presents the first study to use classic numerosity discrimination paradigms to compare the non-symbolic and symbolic foundational numerical skills of a group of younger and older adults. Chapter 3 served to further investigate enhanced symbolic numerical abilities in older age found in chapter 2 using a number priming paradigm. The impact of life experience using numbers on foundational numerical skills in older age was studied in chapter 4, whereby older adults with a degree in mathematics were compared with those without explicit further mathematical education. The final two experimental chapters of the thesis examine the reliable measurement of the Approximate Number System in ageing, considering the impact of inhibitory control and mathematical achievement on acuity. Chapter 5 compares non-symbolic acuity in younger and older adults when using either spatially separated or intermixed non-symbolic dot displays. Finally, chapter 6 directly studies the impact of perceptual variables on ANS acuity in ageing, specifically focusing on total cumulative area, dot size, and convex hull (perimeter) congruency.
The series of experiments presented in the thesis indicate that foundational numerical abilities are preserved in healthy ageing. Specifically, non-symbolic numerical abilities remain stable in older age, whereas foundational symbolic abilities are enhanced, possibly due to lifetime exposure to and experience with symbolic numbers. Furthermore, the thesis demonstrates the importance of task design in measuring non-symbolic numerical abilities in ageing, identifying methodological aspects which may lead to poorer acuity in older adults as a result of decline in other cognitive functions (e.g. inhibitory control). The thesis therefore contributes to the literature regarding numerical cognition in ageing, with foundational numerical abilities found to be preserved in healthy ageing. Preservation of such abilities in healthy ageing poses implications for pathological ageing, in that declined foundational numerical skills may serve to indicate pathological processes.
- Department of Psychology, The University of Hull
- Castronovo, Julie
- Qualification level
- Qualification name
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