The role of semantics in reading and spelling: evidence for the 'summation hypothesis'

This study documents a patient, SA, with an impairment of semantic memory arising as a result of Semantic Dementia (Pick's disease). The patient is impaired at deriving semantic knowledge from both words and pictures. However, his ability to derive semantic knowledge of countries is relatively spared compared to concrete nouns and famous people. The presence of a semantic deficit was used to investigate the role of semantics in reading and spelling. Several novel cueing/priming paradigms are reported which suggest that SA is able to use partial semantic knowledge to constrain his reading and spelling. These results are broadly consistent with the 'summation hypothesis' [27] and suggest that normal reading and spelling may take place by integrating both semantic information and knowledge of direct orthography-phonology correspondences.