This project investigated the effect of paralysis of the eyes on visuospatial cognition. Specifically, we explored whether the vertical gaze palsy associated with a rare neurodegenerative disease called Progressive Supranuclear Palsy (PSP) led to problems with visuospatial attention and spatial short-term memory (STM). It was predicted that neuropsychological patients with PSP would also present with deficits of attention and short term memory that corresponded to their oculomotor dysfunction. To test this hypothesis we examined spatial attention and memory in Fifteen people with PSP (8 female, Mage 69.5, age range: 53–80 years, Mdisease duration 35 months), 16 with Parkinson’s Disease (Mage 68.2, age range 58–78, Mdisease duration 62 months) and 15 Age Matched Controls (Mage 69.7, age range 58–80). We used 2 computerized visual search tasks to measure how quickly participants were able to detect a target item among varying numbers of distractors to measure attention. In one task we the target was defined by a single feature (orientation) and in the other it was defined by a unique conjunction of features (colour and orientation). We also measured the accuracy of their responses. As predicted, feature and conjunction search were significantly slower in the PSP group compared to the other groups, and this deficit was significantly worse for feature compared to conjunction search. The PD group did not differ from AMC on feature search but were significantly impaired on the conjunction search. The PSP group also had a pronounced vertical sSTM impairment that was not present in PD or AMC groups. The data suggest that PSP is associated with specific impairment of visuospatial cognition which is caused by degeneration of the oculomotor structures that support exogenous spatial attention, consistent with the prediction of the Motor Bias Theory of Attention.Humans must process an overwhelming amount of visual information with limited cognitive resources. Spatial attention allows us to select the relevant information. A metaphor for attention is that of a spotlight; only things within the 'beam' of attention are processed. A widely held view is that control of the spotlight is implemented by the motor system. If we wish to attend to something, we plan (but don't necessarily execute) an action that would orient the eyes or hands to that thing. This 'Premotor' theory of attention has been very influential, but does not explain the full range of empirical data. This project will test a new Motor Bias theory of attention which offers a new explanation of the relationship between motor control and attention. Specifically, it is argued that movement preparation influences attention in a stochastic fashion, such that attention is more likely to be allocated to movement goals when (a) the same goal is being selected by more than one effector system, (b) the movement is close to being initiated and (c) the organism is confident that the movement will reliably acquire the desired target. The project aims to precisely characterise the interaction between attention and the motor system by testing these principles. Understanding the psychology of attention will also inform the development of novel rehabilitation techniques for patients with neuropsychological deficits of attention.

Fifteen people with Progressive Supranuclear Palsy (8 female, Mage 69.5, age range: 53–80 years, Mdisease duration 35 months), 16 with Parkinson’s Disease (Mage 68.2, age range 58–78, Mdisease duration 62 months) and 15 Age Matched Controls (Mage 69.7, age range 58–80) volunteered to take part. All participants in the PSP group met the National Institute of Neurological Disorders and Stroke and Society for PSP, Inc. (NINDS-SPSP) (Litvan et al. 2003) criteria for clinically probable or definite PSP. All participants in the Parkinson’s Disease group fulfilled the UK Brain Bank Criteria for a diagnosis of PD (Hughes, Daniel, Kilford, & Lees, 1992). These inclusion criteria were established prior to data analysis. Participants had the choice of participating in their own homes during a home visit by DS or in the Psychology Laboratories at Durham University. Fifteen people decided to participate at home (7 PSP, 7 PD, 1 AMC) and 31 came to the laboratory (8 PSP, 9 PD and 14 AMC). Participants took part having taken their usual medication.