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The aims of this study were (a) to explore the utility of, and make more widely available, an updated and extended version of the Cambridge Semantic Memory test battery, and (b) to use this battery in conjunction with other tests to characterise the profile of several different forms of progressive cognitive impairment: semantic dementia (SD, n = 15), mild cognitive impairment (MCI, n = 7), established Alzheimer's disease (AD) (n = 8), all in comparison to normal controls (n = 45). The semantic battery is useful in a variety of ways for exploring the nature of semantic deficits; on its own, however, it does not provide sensitive differentiation between patients with AD and SD. An assessment including measures of episodic memory and visuospatial abilities as well as the semantic battery is recommended for good characterisation of the cognitive profiles associated with SD and AD.

In Study 1, six patients with semantic dementia were asked to produce drawings of concrete concepts from dictation of their names. The drawings were characterised by a loss of distinctive features. In the artefact domain, this feature loss resulted in representations that were increasingly box-like. In the living domain, as well as distinctive features being lost, there was a tendency for patients to include incorrect features that resulted in more familiar and "prototypical" representations. A second study included two further conditions in the drawing assessment: immediate and delayed copying of line drawings of concrete concepts. Analysis of the drawings produced by three patients with semantic dementia confirmed that overall performance was significantly influenced by the task condition (immediate delayed) and severity of disease. The rate of intruding features, but not of omitted ones, was influenced by the domain of the item, with a greater proportion of intrusions in the living than in the nonliving domain. There was also a significant effect of feature distinctiveness on the proportions of these error types: Intruded features were most likely to come from the pool of properties that are shared across domain.

Several laboratory experiments assessing the ability of patients with semantic dementia to use familiar objects have revealed deficits corresponding directly to the patients' remaining conceptual knowledge for the same items. The same patients, however, were reported to demonstrate normal use of some objects relevant to their everyday lives. The study reported here was designed to explore this apparent discrepancy by examining the influence of personal familiarity with object exemplars, and of the contexts in which they are typically used. Two patients with severe semantic impairment were given single objects that they were still using at home on a regular basis and asked to demonstrate the use of each. Performance on these items was compared with use of perceptually similar and perceptually different exemplars of the same objects. All three sets were tested in the patients' own homes and also in the laboratory. Both patients were significantly more successful at using their own objects than the perceptually different exemplars, while an advantage for 'own' relative to similar exemplars characterized one of the two patients. Familiar home context had no impact on performance. The results suggest that repeated experience with personally familiar objects helps to maintain appropriate responses to them in the face of severely degraded conceptual knowledge.