Project Summary Aphasia is an impairment in the expression or comprehension of language that results from stroke, traumatic brain injury or progressive neurological disease. Approximately two million people in the United States suffer from aphasia, which has profound impacts on quality of life, the ability to return to work and participation in life activities. Research has shown that speech-language therapy, the treatment for aphasia, can significantly improve people’s ability to communicate. However, a major limitation in the field of aphasia rehabilitation is the lack of predictability in patients’ response to therapy and the inability to tailor treatment to individuals. Currently, aphasia treatments are selected largely based on patient’s language abilities and language deficits with little consideration of learning ability, which we call learning phenotype. Learning phenotype has been used to inform rehabilitation approaches in other domains but is not currently considered in aphasia. Our overarching hypothesis is that poor alignment of learning ability and language therapy limits progress for patients and presents a barrier to individualizing treatment. The objectives of the proposed study are to (1) determine the learning phenotype of individuals with aphasia, and (2) examine how lesion characteristics (size and location of damage to the brain), language ability and cognitive ability relate to learning ability. To accomplish our objectives, we will measure implicit (observational) and explicit (rule-based) learning ability in people with aphasia via computer-based tasks. Regression models will be used to examine brain and behavioral factors that relate to learning ability. An in-depth characterization of learning in aphasia is important, as research has suggested that multiple learning systems exist. Furthermore, manipulations to stimuli, task, and feedback can lead to differential recruitment of learning systems and unlock learning potential, particularly in clinical populations (Ashby et al., 1998; 2002; 2003; Ashby & O’Brien, 2005; Davis, Love, & Maddox, 2009; Knowlton et al., 1992; Koenig et al., 2007; Shohamy et al., 2004; Squire & Knowlton, 1995). Our prior work in aphasia supports the hypothesis that individuals with aphasia suffer from impaired learning mechanisms and are sensitive to task manipulations(Vallila-Rohter & Kiran, 2013). These findings demonstrate that that PWA are successful learning in some conditions and not others and provides the rationale for the proposed series of studies focused on characterizing learning abilities in individuals with aphasia. The long-term goal of our research is to maximize rehabilitation outcomes for individuals with aphasia by aligning learning ability with intervention approac...