Memory Interventions to Enhance Long-Term Memory with Atypical and Typical Development

Abstract

Down syndrome (DS) is the most common genetic form of intellectual disability. Individuals with DS present memory and learning difficulties associated with hippocampal impairments. The studies presented in this dissertation investigated different ways of encoding that may rely less on the hippocampus and therefore support better long-term retention for individuals with DS compared to typically developing (TD) mental age-match children. Study 1 investigated two learning conditions where participants learned novel arbitrary picture word associations using fast mapping (FM), an incidental, exclusion-based learning procedure and an explicit encoding learning procedure (Coutanche & Thompson-Schill, 2014). Both DS and TD participants performed similarly for the two conditions across immediate, 5-minute, and 1-week delay. The DS group was not impaired compared to the TD group and maintained what they had learned over the 1-week delay. These findings could have been due to receiving multiple test opportunities at each delay test. Therefore, Study 2 investigated three learning conditions where participants either learned a series of action sequences from two demonstrations and a pause, three demonstrations, or from two demonstrations and a test. The DS group benefited from the test condition at the 1-month delay test. Further comparisons between sequences tested vs. not tested at the 5-minute delay test revealed a testing benefit in both groups. The benefit seen with testing could be influence by a self-bias benefit when given the opportunity to model the action sequences themselves vs. watching another person model the action sequences. Therefore, Study 3 investigated the self-reference effect (SRE), which is a memory advantage for information encoded in reference to one’s self compared to another person or a lower level processing condition. This study consisted of three learning conditions where participants sorted toys and made toy evaluations in reference to themselves, an experimenter, or based on the size of the toy. There was an overall benefit of the size evaluation condition and no difference between the DS and TD group for the self and other condition at immediate or 1-week recognition and source test. Task difficulty could have inhibited SRE in this study. These findings suggest that retrieval practice could be an alternative method of learning that could be beneficial for individuals with DS. Future studies can investigate the benefit of expanded retrieval practice (i.e., combination of spacing and testing). Additionally, more work is needed to better determine the outcome of other ways of learning (i.e., FM and SR) for young children and individuals with DS. Memory interventions and learning strategies can incorporate retrieval practice to support memory difficulties that individuals with DS display.