Learning ability in people with aphasia : how is it different from healthy speakers and what is the role of cognitive functions?

Abstract

Background – The ability to learn new information may have a crucial impact on rehabilitation with people with aphasia (PWA). However, there has been little research on learning in PWA. Although recent studies have shed light on learning and how it might be affected by cognitive functions, the tasks involved are mostly dependent on language and their findings show much inconsistency. This gap in the existing literature inspired this thesis to examine systematically learning and cognitive functions in PWA. Aim – This thesis investigates the ability of PWA to learn new information with particular attention to whether the learning deficit(s), if any, is language-specific or general in all aspects of learning, including non-linguistic material. Also, the potential occurrence of implicit learning is examined to have a comprehensive understanding of learning among PWA. The learning outcomes are further explored in terms of how cognitive functions account for the patterns observed in the various learning tasks involved in the current study. Methods – A series of psycholinguistic experiments, with PWA and two groups (young and older) of healthy participants as controls, are included in the thesis. The experiments conducted investigated the following perspectives of learning: 1) pair-associative learning of materials of various linguistic load; 2) implicit learning in the visual modality; and 3) the effect of massed versus spaced practice on learning. In addition, cognitive profiles of PWA were built through cognitive assessments covering language, memory, attention, and executive functions. The relation between the performances on the cognitive assessments and the learning outcomes were further explored. Results and discussion – The results of the experiments have provided insight into learning in PWA in various learning tasks and how the patterns of learning differ from or resemble those in the control groups. The outcomes of learning demonstrate that, compared to the controls, PWA have reduced learning ability regardless of the type of to-be-learnt material(s). Also, the findings broadly support the evidence that learning can be enhanced through feedback and repeated practice. Further, correlations are restricted among learning tasks, indicating that learning ability in people with aphasia is independent from other cognitive functions.