Abstract
The aim of the present review will consist of discussing the different forms of familiar people recognition disorders observed in the right and left variants of semantic dementia. The review will start with a summary of the main cognitive models of familiar people recognition and of the neuroanatomical correlates of the processing stages proposed by these models. In this section, the role played by ‘familiarity feelings’ and by the properly ‘semantic’ aspects of familiar people recognition in the recognition of familiar people will be taken separately into account. The different roles played by the right and left anterior temporal lobes in each of these components of the system will also be stressed. In the second part of the review, I will discuss results obtained by patients with right and left variants of semantic dementia on tasks assessing ‘familiarity feelings’ and the distinction between general and social knowledge, reaching the following conclusions: (a) recognition disorders shown by patients with a right variant of semantic dementia are due to more to the disruption of pre-semantic mechanisms allowing the automatic generation of familiarity feelings than to properly semantic defects; (b) the right anterior temporal lobe (ATL) supports more the concrete than the abstract components of ‘social knowledge’; (c) the right ATL can store only information that can be represented in a concrete pictorial format whereas the left ATL mainly stores information that can be represented only through abstract linguistic propositions (240).