Psychophysiology of Perception



The aim of the Psychophysiology of Perception laboratory is twofold:

(1) to conduct scientific experiments to learn about perception and psychophysiology. This includes (i) learning about perception using physiological (including neuroscientific) measures, (ii) learning about biological and neuroscientific mechanisms underlying psychophysiological responses, and (iii) learning about how mental processes are reflected in physiological responses.

(2) to conduct valorisation studies in practice to utilize scientific knowledge for society in general, governments, education, and commercial businesses. This includes (i) reading a person's mental perceptions, states, thoughts, and intentions with physiological measures, (ii) finding biomarkers for mental and physical abnormalities, (iii) applying biofeedback to improve motor behavior, cognitive skills, and physical well-being.

Scientific fields:

The "Psychophysiology of Perception Lab" is active in the fields of visual perception, consciousness, attention, visual neuroscience, ophthalmology, motor coordination, pupillometry, (remote) photoplethysmography, cardiography, and behavior research.

Govermental institutes and commercial fields:

Our lab is also active in human recruitment, human resources, media, education, marketing, and health care.


We apply a large variety of methods, borrowed from many different disciplines, including quantitative psychophysics (reaction times and performance), qualitative questionnaires (IQ, etc.), gaze-tracking, pupillometry, heart rate (variability), ECG, food supplementation, EEG, TMS, and fMRI.


The material in the laboratory consists of multiple eye-trackers, industrial cameras, electroencephalograpy (EEG) setups, TMS setups, fMRI scanners (3-7T), and psychophysical settings.


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Marnix Naber

Head of laboratory

Google Scholar

Felix Hermsen

External PhD student


Brendan Portengen

PhD student


Tijn Knaap

Master student


Mitchel Kappen

Master student



International scientific collaborations:

Prof. George A. Alvarez (Vision Sciences Laboratory at Harvard University): expert on attention, working memory, and perception
Dr. Peter Murphy (Department of Neurophysiology at University Medical Center Hamburg): expert on pupillometry
Dr. Julian Tillmann (Department of Psychology at King's College London): expert on eye-tracking and autism
Dr. Jan Brascamp (Department of Psychology at Michigan State University): expert on eye-tracking and consciousness

National scientific collaborations:

Prof. Serge Dumoulin (Spinoza Centre for Neuroimaging): expert on fMRI and population receptive field mapping
Dr. Giorgio Porro (Ophthalmology of University Medical Center Utrecht): expert on diagnostics of cerebral visual impairments
Dr. Douwe Bergsma (Cognitive Neuroscience at Medical Center Nijmegen): expert on hemianopia
Prof. Mies van Genderen (Bartimeus Zeist): expert on visual impairments

Local scientific collaborrations:

Prof. Stefan van der Stigchel: expert on attention, working memory, and perception
Dr. Ben Harvey: expert on fMRI and population receptive field mapping
Dr. Tanja Nijboer: expert on unilateral spatial neglect
Dr. Joris Elshout: expert on diagnostic tools for hemianopia and unilateral spatial neglect
Dr. Nathan van der Stoep: expert on multisensory integration and eye-tracking
Dr. Sjoerd Stuit: expert on machine learning, emotions, and consciousness
Dr. Chris Paffen: expert on psychophysics and consciousness

Collaboration in industry:

Neurolytics: a HR company that uses psychophysiological measurements as biomarkers of motivation, interest, and stress
Holland Startup: a venture builder that supports startups
Bloakes: a marketing research company


Joeri van Helden

Master student


Carlien Roelofzen

Master student


Yentl de Kloe

Master student



Heart rate detection

HR(V) measurements with a webcam.


Eye-tracking in a large field stereoscope

Dichoptic eye tracking with one screen per eye.


Motion-induced blindness

An illusion used to study consciousness.

More info

Monocular rivalry

Illusion with two distinct percepts that alternate over time.



June-August 2018

BNR nieuwsradio - hartslag meten door de webcam:

Volkskrant Al te menselijke robots maken ons ongemakkelijk

RTV Utrecht We vinden menselijke robots eng en daarom zijn ze (nog) niet effectief

Universiteit Utrecht Nieuws Menselijke robot als griezelig ervaren

De utrechtste internet courant Onderzoeker UU: "Bijna menselijk is niet goed genoeg voor robots"

Numerikare Menselijke robot als griezelig ervaren

November 2013

Mare Rubriek Geklungel na-apen

Science Guide Na-apen belangrijker dan winnen

NWO Imiteren tegenstander onbewust belangrijker dan winnen

HoeZo? NTR Radio - Imiteren:

May 2013

In het 8 uur journaal - zon & de pupil:

HoeZo? NTR Radio - pupil reacties op plaatjes van de zon:


Volskrant Zon op foto verkleint pupillen ook

NU.NL Zon op foto verkleint pupillen ook

NWO Kijken naar een foto van de zon verkleint je pupillen ook

De morgen Zon op foto verkleint pupillen ook

Wetenschapsforum Kijken naar een foto van de zon verkleint je pupillen ook

Standaard Ook de zon op foto doet pupillen verkleinen

Scientias Pupil neemt het zekere voor het onzekere en verkleint bij foto van de zon

Het nieuwsblad Pupillen verkleinen door naar foto van de zon te kijken

RTL nieuws Pupil verkleint ook door zon op foto


van der Stoep, N., van der Smagt, M., Naber, M. (In prep.). Additive effects of multi-sensory stimulation on pupil responses.

van Helden, J., Naber, M. (In prep.). Links between pupil responses and early visual-evoked potentials in EEG.

Murphy, P., Naber, M. (In prep.). Pupillometric investigation into speed and accuracy in aimed screen cursor movements with a computer mouse.

Naber, M., Stuit, S., Paffen, C.L.E., van der Stigchel, S. (In prep.). Adaptation to stimulus contrast and eye conflict lengthen episodes of non-exclusive perception in binocular rivalry.

Hermsen, F., van Loon, G., Naber, M. (In prep.). Pupil size is unaffected by mental effort during product evaluations on webpages.

Hermsen, F., van Loon, G., Naber, M. (In prep.). Pupil dilation as a marker of product preference on webpages.

van der Kooij, K., Naber, M. (Under revision). An open-source remote heart rate imaging method with practical apparatus and algorithms.

Mathot, S., Naber, M. (2018). There is no evidence that pupil mimicry is a social phenomenon. PNAS

Derksen, M., van Alphen, J., Schaap, S., Mathot, S., Naber, M. (2018). Pupil Mimicry is the Result of Brightness Perception of the Iris and Pupil. Journal of Cognition

Ding, Y., Naber, M., Gayet, S., van der Stigchel, S., Paffen, C.L.E. (2018). Assessing the generalizability of eye dominance across binocular rivalry, onset rivalry, and continuous flash suppression. Journal of Vision

Naber, M., Roelofzen, C., Fracasso, A., Bergsma, D.P., van Genderen, M., Porro, G.L., Dumoulin, S.O. (2018). Gaze-contingent flicker pupil perimetry detects scotomas in patients with cerebral visual impairments or glaucoma. Frontiers in Neurology

Reuten, A., van Dam, M., Naber, M. (2018). Pupillary responses to robotic and human emotions: the uncanny valley and media equation confirmed. Frontiers in Psychology

Brascamp, J.W., Naber, M. (2017). Eye tracking under dichoptic viewing conditions: a practical solution. Behavior Research Methods

Lippelt, D.P., van der Kint, S., van Herk, K., Naber, M. (2016). No acute effects of choline bitartrate food supplements on memory in healthy, young, human adults. PLoS ONE

Naber, M., Vedder, A., Brown, S., Nieuwenhuis, S. (2016). Speed and lateral inhibition of stimulus processing contribute to individual differences in Stroop-task performance. Frontiers in Psychology

Naber, M., Brascamp, J. (2015). Commentary: Is the Frontal Lobe Involved in Conscious Perception? Frontiers in Psychology

Naber, M., Eijgermans, W., Herman, A., Bergman, A., Hommel, B. (2015). Similarity of actions depends on the functionality of previously observed actions. JEP: HPP

Naber, M., Hommel, B., Colzato, L.S. (2015). Improved human visuomotor performance and pupil constriction after choline supplementation in a placebo-controlled double-blind study. Scientific Reports

Fraessle, S., Sommer, J., Hansen, A., Naber, M., Einhaeuser, W. (2014). Binocular Rivalry: Frontal activity relates to introspection and action, but not to perception. Journal of Neuroscience

Naber, M., Alvarez, G.A., Nakayama, K. (2013). Tracking the allocation of attention using human pupillary oscillations. Frontiers in Psychology

Naber, M., Vaziri Pashkam, M., Nakayama, K. (2013). Unintended imitation affects success in a competitive game. PNAS

Naber, M., Stoll, J., Einhaeuser, W., Carter, O. (2013). How to become a mentalist: Reading decisions from a competitor's pupil can be achieved without training, but requires instruction. PLoS ONE

Naber, M., Nakayama, K. (2013). Pupil responses to high-level image content. Journal of Vision

Naber, M., Fraessle, S., Rutishauser, U., Einhaeuser, W. (2013). Pupil size signals novelty and predicts later retrieval success for declarative memories of natural scenes. Journal of Vision

Naber, M., Hilger, M., Einhaeuser, W. (2012). Animal detection and identification in natural scenes: Image statistics and emotional valence. Journal of Vision

Naber, M., Fraessle, S., Einhaeuser, W. (2011). Perceptual Rivalry: Reflexes reveal the gradual nature of visual awareness. PLoS ONE

Naber, M., Carlson, T.A., Verstraten, F.A.J., Einhaeuser, W. (2011). Perceptual benefits of objecthood. Journal of Vision

Naber, M., Gruenhage, G., Einhaeuser, W. (2010). Tri-stable stimuli reveal interactions among subsequent percepts: Rivalry is biased by perceptual history. Vision Research

Naber, M., Carter, O., Verstraten, F.A.J. (2009). Suppression wave dynamics reveal visual field anisotropies and sensitivity to inducer strength. Vision Research

Paffen, C.L., Naber, M., Verstraten, F.A.J. (2008). The spatial origin of a perceptual transition in binocular rivalry. PLoS ONE