John C. Marshall

For the British musician, see John C. Marshall (musician).

John C. Marshall (1939–2007) was one of the United Kingdom's foremost experimental psychologists, whose research on language disorders and dyslexia helped pioneer the development of the influential discipline of psycholinguistics and cognitive neuropsychology.

After graduating with a BA in 1960 and a PhD in 1967 from the University of Reading, he worked in a variety of clinical settings, researching the effects of acquired brain damage and developmental pathology on higher mental functions including language, spatial cognition, memory, reasoning, and decision making. Throughout this period, he held academic teaching and research posts at the Universities of Oxford, Edinburgh, and Nijmegen and also held visiting positions at Harvard, McGill, and the University of California, Los Angeles.

In 1980, he became a member of the Medical Research Council’s External Scientific Staff and Director of the Neuropsychology Unit at the Oxford University Department of Clinical Neurology. In 1997, he was appointed Professor of Neuropsychology at Oxford.

Research

John Marshall began his cognitive-neuropsychological career studying impairments of word-retrieval and his research in this field continues to have a significant and enduring impact worldwide. Alongside Freda Newcombe, he initiated some of the first cognitive neuropsychological investigations of reading. Remarkably, he achieved this with two papers-now rightly recognised as classics. The first on semantic errors in acquired dyslexia, published in 1966, stimulated intensive research on deep dyslexia culminating in the highly influential book, Deep Dyslexia, published in 1980 and coedited by Max Coltheart, Karalyn Patterson and Marshall. Even more influential was his second classic paper, Patterns of Paralexia (1973) again with Freda Newcombe which described three basic subtypes of acquired dyslexia (surface dyslexia, deep dyslexia, and visual dyslexia) and subsequently interpreted in relation to specific information-processing theories of reading. This paper continues to be well cited and its contemporary importance is shown by the fact that its citation rate per annum continues to increase.

Marshall was also responsible for initiating and championing some of the early cognitive-neuropsychological studies on developmental dyslexia through his work in the 1970s and early 1980s with his students, Jane Holmes and Christine Temple. In these landmark studies, he again drew analogies between acquired and developmental aspects of reading disorder, creating debates that have continued over more than 20 years. The legacy of this approach continues to exercise a powerful impact on current investigations of developmental dyslexia.

A second major strand of his research began in the mid-1980s when exploring the disabling condition of visuospatial neglect. Research over the past 30 years from his group convincingly showed that, far from being a unitary condition, neglect was a protean disorder whose symptoms could selectively affect different sensory modalities, cognitive processes, spatial domains, and coordinate systems. Marshall’s work helped disentangle some of the theoretical factors that were thought to underlie the core deficits in visual neglect. For example, it was generally assumed that patients with neglect had no awareness of objects presented in the neglected field. However, Marshall and Halligan (1988) showed that despite apparent unawareness for relevant features on the affected left side, patients could be influenced by information on the neglected side. In a second study, again published in Nature, Halligan and Marshall (1991) showed the first convincing evidence in humans for a dissociation between extrapersonal space and peripersonal space. Subsequently, dissociations between left neglect in peripersonal, extrapersonal space, and more recently back space (Viaud-Delmon, Brugger, & Landis, 2007) have been reported.

Seeing the potential for applying the cognitive neuropsychological approach to understanding psychopathology, John’s research over the past decade has also made a significant contribution by reawakening interest in cognitive neuropsychiatry. Examples where the approach has been explicitly used to explain neuropsychiatric conditions include hallucinations, supernumerary phantom limbs (Halligan, Marshall, & Wade, 1994), reduplication, somatoparaphrenia, and hysterical conversion (Halligan & David, 1999; Marshall, Halligan, Fink, Wade, & Frackowiak, 1997), not to mention publication of one of the first books that helped inspire and refine the field of cognitive neuropsychiatry, Method in Madness (Halligan & Marshall, 1996) as an emerging subdiscipline.

Despite originally questioning ‘whether neuroimaging was ever going to contribute to neuroscience’’Marshall in the mid-1990s, began a series of cognitive neuroscience studies first at the FIL in London but subsequently with Gereon Fink in Cologne that explicitly made use of functional neuroimaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) to address specific research questions (Fink, Marshall, Noth, & Zilles, 2003). These studies explored the underlying neuroanatomy/neurophysiology implicated by traditional psychological tasks thereby allowing a direct and important comparison with lesion-based results.

References

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