The uneven profile of memory development in Down Syndrome

• Main Author: Hughes, Kate M. O.
• Published: Birkbeck (University of London) 2018
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.738104

This thesis explores memory development in children with Down syndrome (DS) between aged 3 years and 9 months and 14 years and 5 months (N=43). While memory has been extensively explored in older individuals with DS, relatively little work has considered the development of memory in childhood in DS, in part due to the difficulty of assessing memory in individuals with lower levels of ability. The project was innovative in applying a mixture of original and pre-existing tasks to this population, in order to characterise a wide range of memory abilities at varying levels of cognitive demand. These abilities were initially compared between those with DS and typically developing individuals by age group, early childhood (3 years 9 months to 8 years 4 months) and late childhood (9 years 9 months to 14 years 5 months). Standardised tasks were used to produce mental-age equivalents and raw scores for verbal and non-verbal memory abilities (BPVS, BAS II pattern construction). Study 1 examined object and object-in-place recognition using eye-tracking, using a low demand methodology that excluded few participants. Study 2 examined verbal working and long-term memory abilities overall, as well as learning and forgetting rates. Primacy, recency and mid-list recall rates were also analysed to shed light on strategies of encoding. Study 3 examined spatial working and long-term memory abilities, as well as forgetting rates. Study 4 examined multimodal associative immediate and delayed memory, using a spatialauditory associative eye-tracking paradigm. Study 5 examined the relationships between sustained attention, inhibition, and sleep behaviour measures, as these faculties are implicated in the development of memory abilities. Finally, in Study 6, cross-sectional developmental trajectories were constructed for all memory measures to ascertain if base levels or gradients of change significantly differed, either with respect to chronological age or domain-relevant mental age measures, in comparison to a sample of typically developing children. Overall, the project charted the emergence of an uneven profile of memory abilities across childhood in DS.