School of Psychology

Main Current Projects

See it, grab it: Control of automatic sensorimotor behaviour in health and disease (funded by Wellcome Trust, and joint with UCL).

How does the brain control the links between perception and action, and what happens when such control is disrupted by brain damage? Traditionally, the control of action has been separated into automatic and volitional processes. Our hypothesis is that these two activities are in fact inextricably related. Visual objects automatically activate (prime) motor plans which facilitate actions towards these objects. But if our actions are not always to be driven by environmental stimuli, such priming must be inhibited to allow alternative goals. We want to understand how automatic control processes are involved in such flexible, ‘volitional’ control of behaviour, and why individuals differ in their ability to control basic behaviour. We employ behavioural tasks in healthy and brain-damaged people, and use the imaging facilities in CUBRIC.

How are eye movement decisions made? (application to ESRC)

To explain decisions without recourse to a separate intelligent agent (the homunculus problem), we must assume they arise from some combination of sensory input (evidence), the dynamic state the brain is in when those inputs arrive (including memory, goal states etc), and some random noise. All models of decision making envisage an integration of these ingredients into accumulating activity in favour of one choice or another. As soon as the accumulation for one choice reaches a threshold, the decision is made. We use the umbrella term “first-to-threshold” to refer to this way of conceptualising decisions.

Thus the probability of a simple action being chosen should depend on how quickly the accumulation process for that action tends to reach threshold. This is also a key component in the time it takes to initiate the action. Choice should therefore be inextricably linked to response times. However, the first-to-threshold idea is so widespread and so intuitive that this fundamental prediction has been overlooked, despite it having the power to overturn all current models, indeed our entire conceptualisation of how a brain can make decisions. Yet our preliminary data suggest that the prediction is incorrect.

Why don’t we see what our eyes are telling us? (funded by ESRC).

Our eyes and visual system introduce various distortions and imperfections into the visual image, but our everyday perception appears immune to them. How is this achieved? We are investigating two aspects of this issue: 1) how does macular pigment in the retina influence colour perception? 2) why do we not see colour after-effects all the time, even though they are quick and easy to elicit in demonstrations (and why do they go away or come back when we blink?)

Automatic influences on eye movement planning and attentional shifts.

Variousrelated experiments are ongoing in this category, including: 1) investigations of saccade distractor effects and their relationship to GABA (an inhibitory neurotransmitter);2) subliminal attentional triggers and the retinotectal pathway 3) how saccade curvature is related to response inhibition; 4) how saccade plans cope with nystagmus (do the voluntary systems know what the subcortical automatic systems are doing?)

Funding

Wellcome Trust project grant (2009-2012, £426 191): See it, grab it: Control of automatic sensorimotor behaviour in health and disease. Petroc Sumner, Masud Husain, Krish Singh, Bob Rafal. Research Associates: Fred Boy (Cardiff) and Jen McBride (UCL)

ESRC project Grant (2009-2010, £82 039) Is perceived colour altered when we move our eyes. Petroc Sumner and Aline Bompas.

BBSRC Project Grant, (2005-2008, £194 578):Using S cones to investigate the role of the superior colliculus in automatic visual processes. Petroc Sumner and Masud Husain. Research Associates: Elaine Anderson and Aline Bompas

WICN pilot grants (2007-2009, £33K) Control of automaticity and automaticity of control; Influence of frontal eye fields on contrast perception; GABA and saccade inhibition.

We have also been supported by Nuffield and Wellcome summer scholarships, and by Royal Society travel and small project grants.

Team and Internal Collaborators

Aline Bompas (ESRC Postdoctoral Research Associate; Eye movement and colour projects)

Fred Boy (Wellcome Postdoctoral Research Associate; ‘See it, grab it’ project).

Krish Singh (all imaging aspects of our projects).

Chris Chambers and team (attention project and TMS).

Suresh Muthukumaraswamy (MEG experiments)

John Evans (fMRI and MR spectroscopy)

Tom Freeman (nystagmus, smooth pursuit and saccades)

Simon Rushton (visual anomalies in Huntingdon’s Disease, fMRI of objects in motion)

Bill Macken and Dylan Jones (motor activation by auditory sequences)

Ursula Budnik, Chris Allen, Georgina Powell, Sian Griffiths, David Maidment. (PhD students; see Postgraduate page).

External Collaborators

Masud Husain and Jen Mcbride (Institute of Neurology and Institute of Cognitive Neuroscience, UCL, London; ‘See it, grab it’ project)

Bob Rafal (Bangor; patient studies)

Richard Edden (John Hopkins, Baltimore; MR spectroscopy)

Robin Walker and Frouke Hermens (Royal Holloway; saccade curvature and inhibition)

Iain Gilchrist (Bristol; variability of saccade latency)

Elaine Anderson (Optometrist and UCL; previously Post-doc on BBSRC grant)

Parashkev Nachev (Institute of Neurology; control, inhibition and conflict)

Monica Busse-Morris (Physiotherapy, Cardiff; visual anomalies in Huntingdon’s Disease)