Prof Petroc Sumner- BA MA PhD Cantab

Professor and Head of School

Research group:
Cognitive science
029 208 70091
Tower Building, Park Place

Research summary

Perception and action:

How do visual signals, even ones that we do not consciously perceive, trigger actions? How do we control our behaviour so that we do not reflexively respond when we don’t want to? Why do people differ from each other in these basic mechanisms?

Control of basic behaviour can be disrupted by brain damage or degeneration or in mental disorders, and lapses occur often in all of us. Our research aims to help us understand the exact reasons why.

We use a range of methods with both healthy volunteers and patients, integrating precise behavioural measures (including eye tracking) with imaging (fMRI and MEG) and spectroscopy.

A non-specialist review relating to our work can be found in: Sumner, P. and Husain, M (2008). At the edge of consciousness: automatic motor activation and voluntary control. The Neuroscientist, 14, 474-486. [pdf]. We also occasionally write articles in the press (e.g. Riot control; Science reporting)

Science in the media:
Recently we have also launched a project investigating where things go wrong in the communication between scientists and journalists, with a view to trying to improve the way health-related research is reported in the press. See for more information.

Teaching summary

Levels 1 and 2: I teach introductory lectures on perception, biological psychology and testing evolutionary theories (PS1016 and PS1014), run perception practicals (PS2009), and give tutorials on research, perception, cognition and abnormal psychology (supporting PS1014, PS2003, PS2008, PS2009).

Level 3: In 2011/12 Tom Freeman, Simon Rushton and I offer a 20-credit module in vision and action, which integrates various topics concerning how actions affect perception and how visual information is used to guide both unconscious and conscious action plans.  I supervise projects on action control and perception.

I am also coordinator for the Bioscience students taking psychology modules as part of their Neuroscience pathway.

Selected publications (2014 onwards)


Online publications

Full list of publications


Media activities

Science Journalism

The Guardian

The Levespm Inquiry

Le Monde France

The Guardian

The Guardian

Research topics and related papers

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?)


ESRC (2013-2016, £633,613) A framework and toolkit for understanding impulsive action. Petroc Sumner, Aline Bompas, Chris Chambers, Casimir Ludwig, Frederick Verbruggen, Fred Boy.
ESRC (2103-2016) Grant-linked studentship: The role of flexibility in impulsivity. Petroc Sumner, Chris Chambers.

ESRC (2103-2016) Grant-linked studentship: The role of flexibility in impulsivity. Petroc Sumner, Chris Chambers.

BIAL foundation (39K Euro) The Neurochemistry of Gambling-Related Impulsive Cognition and Decision-Making: a Multimodal Imaging Approach. PI Fred Boy.

Alcohol Research UK (ARUK) studentship award (2012-2015) ‘Individual differences in the effect of alcohol on cognitive control.’

British Psycology Society (2012) ‘Are press releases to blame in the miscommunication of science?’ £3,400.

Wellcome Trust Value in People award (supervisor/sponsor of Fred Boy). £40500 (2011-2012).

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.

Research collaborators


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. James Harrison (PhD students; see Postgraduate page).


Aline Bompas

Fred Boy

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)

Postgraduate research interests

If you are interested in applying for a PhD, or for further information regarding my postgraduate research, please contact me directly (contact details available on the 'Overview' page), or submit a formal application here.

Current students

Annie Campbell. Annie started in Oct 2012, and her project is on alcohol and cognitive control.

James Harrison (co-supervised with Tom Freeman). James is investigating the interactions between automatic and voluntary control in eye movements. The first step is to find out exactly what the ‘antisaccade task’, commonly used in clinical populations, really measures.

Geoffrey Megardon. Geoffrey started in Oct 2012, and his project is modelling the control of basic actions, such as eye movements.

Mark Mikkelson. (co-supervised by Krish Singh and John Evans). Mark started in Oct 2012, and works on measuring GABA levels in the human brain using magnetic resonance spectroscopy.

Georgina Powell (co-supervised with Aline Bompas). Georgie’s project addresses the question: why do we often not see what our eyes are telling our brain? The main question we hope to investigate is why we don’t see colour afterimages very much in everyday life, even though they are very easy to evoke in demonstrations.

Kacper Wieczorek. (co-supervised by Krish Singh). Kacper started in Oct 2012, and works on vision, GABA and MEG.

Laura Whitlow (co-supervised by Krish Singh, Tom Freeman and James Walters). Laura started in Oct 2012, and works on differences in vision, GABA and MEG in schizophrenia.

Previous students

Sian Griffiths (co-supervised with Krish Singh). Sian investigated the relationship between positive and negative BOLD responses, GABA and gamma frequency in V1. She now has a post doc post at Nottingham.

Chris Allen (co-supervised with Chris Chambers). Chris is investigating what makes us aware or not aware of visual stimuli. The project involved transcranial magnetic stimulation (TMS) and magnetoencephalography (MEG). Chris has a post doc post with us until Jan 2013.

David Maidment (main supervisor: Bill Macken). David’s project was on short term memory. He has got a post doc post at the MRC Institute for Hearing in Nottingham.

Christina Howard (co-supervised with Alex Holcombe and Dylan Jones). Christina studied how attention is allocated to multiple dynamic objects (Alex Holcombe was her primary supervisor, but he left Cardiff to take a position in Sydney in Christina’s final year). Christina also investigated the relationship between attention and crowding. Via post-doctoral positions in Bristol, Sydney and Birmingham, Christina now holds a lectureship in Nottingham Trent University.

Lois Grayson (co-supervised with Alex Holcombe and Josie Briscoe). Lois studied perceptual integration in Autism also the relationship between perceptual integration and autistic spectrum traits in healthy students (I took over a supervisory role after Josie took a position in Bristol and Alex in Sydney). Lois has gone on to a postdoctoral position in the Institute of Psychiatry, London.

Ursula Budnik. Ursula investigated the effect brain damage to frontal and subcortical areas has on basic perceptual ability. It is thought that via top-down pathways, even brain areas associated mostly with action control can affect basic perception. Ursula also used subliminal priming to investigate differences between in the processing of foveal and peripheral stimuli. Ursula now has a post with the Max-Plank Institute in Leipzig, in collaboration with the ICN in London.

Undergraduate education

1996: BA in Natural Sciences, 1st Class, University of Cambridge. Foundation Scholarship, Caldwell Scholarship and Bishop Green Cup.

Postgraduate education

2000: PhD, Dept Experimental Psychology, University of Cambridge. Supervised by J.D. Mollon.

2003: Diploma of Imperial College, London, in Advanced Study in Learning and Teaching.

Awards/external committees

David Marr Medal, Applied Vision Association.


2003: Experimental Psychology Society

2004: Higher Education Academy

2005: Applied Vision Association

2007: American Physiological Society

2009: ESRC peer review college

Other Duties

Grant reviewing: BBSRC; ESRC; MRC; Wellcome Trust; Australian Research Council; National Science Foundation (USA); NWO (The Netherlands).

Consulting Editor for JEP, HPP.

Journal reviewing (23 different journals, including Science, PNAS, Current Biology, Neuron, J. neuroscience).

Invited talks and symposia (e.g. University of Western Australia, Perth; University of Queensland, Brisbane; University of Geneva; Rank Prize Fund, Kingston (Canada), John Hopkins (Baltimore), AVA, BOMG, HBM, ICON, ECEM)

PhD examining (internal and external).


2000-2006: Lecturer, Division of Neuroscience and Psychological medicine, Imperial College London.

2006-present: Lecturer/Senior Lecturer/Reader, School of Psychology, Cardiff University