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Petroc Sumner

Dr Petroc Sumner

Professor and Head of School, School of Psychology

School of Psychology

+44 29208 70091
Tower Building, 70 Park Place, Cardiff, CF10 3AT


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.


























Book sections


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



  • 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)



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

Honours and awards

  • David Marr Medal, Applied Vision Association.

Professional memberships

  • 2003: Experimental Psychology Society
  • 2004: Higher Education Academy
  • 2005: Applied Vision Association
  • 2007: American Physiological Society
  • 2009: ESRC peer review college

Academic positions


  • 2000-2006: Lecturer, Division of Neuroscience and Psychological medicine, Imperial College London.
  • 2006-present: Lecturer/Senior Lecturer/Reader, School of Psychology, Cardiff University

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).