The impact of autobiographical experience on meaning: Reply to Graham, Lambon Ralph, and Hodges

We have shown that in semantic dementia (Snowden, Griffiths, & Neary, 1994, 1995, 1996) patients knowledge is significantly influenced by its relevanc e to their autobiographical experience. Graham, Lambon Ralph, and Hedges (1 997), in an investigation of the autobiographical effect, found that genera l knowledge of sports in which their semantic dementia patients participate d was no better than that for other sports and inferred that their data con tradict the hypothesis that experience helps to preserve meaning. The purpo se of this paper is to address the apparent conflict of views. First, we sh ow that the hypothesis under investigation in the Graham et al. study, that experience maintains all the knowledge about a concept, is not one to whic h we subscribe and that much of their data is in fact consistent with our o wn findings. We highlight similarities in our interpretation of the autobio graphical effect. We then examine those areas in which our opinions appear to diverge. We argue that autobiographically relevant knowledge can be expl icit and is not merely implicit and is semantic and not merely procedural. We argue, moreover, that it is truly semantic and not merely semantic-like. We reconsider the nature of semantic knowledge and the relationship betwee n medial temporal and temporal neocortical memory systems.