Processing deficits for familiar and novel faces in patients with left posterior fusiform lesions.
Bottom Line: Identification of famous faces was found to be compromised in both expressive and receptive tasks.Interestingly, discrimination of faces that varied in terms of feature identity was considerably better in these patients and it was performance in this condition that was related to the size of the length effects shown in reading.These results suggest that the sequential part-based processing strategy that promotes the length effect in the reading of these patients also allows them to discriminate between faces on the basis of feature identity, but processing of second-order configural information is most compromised due to their left pFG lesion.
Affiliation: Research Centre in Brain and Behaviour, Liverpool John Moores University, UK.Show MeSH
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Mentions: The mechanisms underpinning the face identification deficits in PA therefore remain unclear. This work aimed to examine face processing in a large sample of patients with left pFG damage and associated reading deficits of varying severity. We first explored whether nine patients showed deficits in familiar face identification in both expressive and receptive tasks. Although these patients do not present with prosopagnosia, they may well be impaired in their speed of identification, even for familiar faces that offer the opportunity for top-down support. We then assessed performance for 16 patients on a discrimination task involving novel faces that varied on feature identity, second-order spacing (by manipulation of internal distribution or external contour), or both. To the extent that letter identification can be preserved in PA (Behrmann & Plaut, 2013a), but that problems in the perception of the configuration of letters undermines fluent reading, we expected our patients with left pFG damage will show particular deficits for the second-order spacing conditions but relatively good performance for the feature identity condition. This prediction agrees with the finding that, in normal participants, more activation is seen for the spacing than featural condition in both right and left pFG, while higher activation for the featural than spacing condition is observed mainly in frontal regions (see Fig. 3 and Table 2, Maurer et al., 2007). If damage to left pFG undermines the configural processing both for words and faces, then we would further expect that novel face processing deficits would be linked to the severity of the reading disorder, both categorically and correlationally.
Affiliation: Research Centre in Brain and Behaviour, Liverpool John Moores University, UK.