The role of conceptual knowledge in object use Evidence from semantic dementia

Abstract

It has been reported that patients with semantic dementia function well in everyday life and sometimes show striking preservation of the ability to use objects, even those specific objects for which the patient has degraded conceptual information. To explore this phenomenon in nine cases of semantic dementia, we designed a set of semantic tests regarding 20 everyday objects and compared performance on these with the patients' ability to demonstrate the correct use of the same items. We also administered a test of mechanical problem solving utilizing novel tools, on which the patients had completely normal ability. All but the mildest affected patient showed significant deficits of naming and on the visually based semantic matching tasks. Object use was markedly impaired and, most importantly, correlated strongly with naming and semantic knowledge. In a small number of instances, there was appropriate use of an object for which the patient's knowledge on the semantic matching tasks was no better than chance; but this typically applied to objects with a rather obvious relationship between appearance and use, or was achieved by trial and error. The results suggest that object use is heavily dependent upon object-specific conceptual knowledge, supplemented to some degree by a combination of visual affordances and mechanical problem solving.

When the zebra loses its stripes but is still in the savannah: Results from a semantic priming paradigm in semantic dementia

“…This relative independence is quite astonishing, given that in other degenerative diseases (including AD), functional disorders hamper everyday life at a far earlier stage in the pathology. Regarding their functional abilities, SD patients have long been described with preserved object use despite their semantic memory breakdown (Buxbaum et al, 1997;Hodges et al, 2000;Lauro-Grotto et al, 1997). Hodges et al (2000) and Bozeat et al (2002) isolated several factors explaining the spared abilities to use objects: the residual conceptual knowledge, the conceptual familiarity, the personal familiarity and the visual object affordances (i.e., mechanisms that support object use directly from visual and/or tactile input).…”

“…In their semantic priming task, they included this kind of relationship as a control condition (e.g., "needle" priming "haystack") and observed a normal priming effect in SD patients. Moreover, "used to perform an action" relationships could, to some extent, implicate the visual object affordances (i.e., mechanisms that support object use directly from visual and/or tactile input) which were isolated by Hodges et al (2000) as one of the factors accounting for spared abilities to use objects in SD. We could thus ascribe the spared and robust priming effect previously observed in SD patients to the excessively broad types of attributes included under the label "functional condition".…”

Acquiring an understanding of design: evidence from children's insight problem solving

“…the combination of mechanical affordances and goals tested by asking: "Which object can lift the weight? "; Hodges, Bozeat, Ralph, Patterson, & Spatt, 2000;Hodges, Spatt, & Patterson, 1999). Though other explanations are possible, one way of characterizing this pattern of impairment is in terms of these adults being forced to rely on core knowledge systems (object mechanics, intuitive psychology) to reason about object function.…”

P2‐241: Focal Temporal Pole Atrophy and Network Degeneration in Semantic Variant Primary Progressive Aphasia

“…Patients with svPPA usually exhibit impaired semantic memory across all modalities and object categories Hodges et al, 2000;Lambon Ralph et al, 2007;Luzzi et al, 2007;Goll et al, 2010;Piwnica Worms et al, 2010), although initially have preserved performance for concepts with rich auditory or motor characteristics (Hoffman et al, 2012). Previous work has associated diffuse atrophy in the left anterior temporal lobe with semantic processing deficits in semantic dementia (Mummery et al, 2000).…”