Dr Macdonald Critchley gave his Semon Lecture in 1951. Through his lecture, he outlines different defects arising from aphasia. He then goes on to demonstrate that dysarthria, dysphasia and articulatory dyspraxia, whilst possible occurring together, are separate phenomena.
Macdonald Critchley was born on the 2nd of February 1900. Unusually for a Semon Lecturer, he actually specialised as a neurologist and was President of the World Federation of Neurology for some time. He wrote a great number of articles and books, with his book on the parietal lobes remaining the reference book for the subject.