Vision is the dominant sense in humans. We built our cities and buildings, furnished our homes and offices, and designed our transportation and appliances with the assumption that the users will have full vision - with occasional concessions for the visually impaired. We point at things, play sports, drive cars, and read body and facial expressions. Surface-rendered me and my brain from anatomical MRI When we are not actively interacting with our world, we watch television: on average 4 to 5 hours per day. In short, we live in a sighted culture.

The importance of vision is also reflected in our brain. About 25% of the human cerebral cortex is involved in visual processing, which is more than for any other sense. In closely related primates, such as macaques, the relative cortical surface area occupied by the visual system is even larger: about 50%. But the absolute cortical surface area of macaque visual cortex is about 20% of that in humans despite similar numbers of nerve fibers coming from the eyes in both species. The increased number of neurons in the human visual cortex presumably reflects additional visual processing required for uniquely human skills such as language.

Studies of the visual system have a long history. The detailed knowledge of the visual system draws many scientists to vision. These scientists are not studying the visual system per se. They use the visual system either as a model to develop and validate new methods, or they use the visual system to investigate other neural properties, such as attention or consciousness. In short, I study the visual system not just for the sake of vision itself, but also as a model for the rest of the brain and as a rich database to validate new methods.

My career has been focused on the organization and function of the visual system from neural, clinical, behavioural and computational perspectives. On this topic, I have published original manuscripts, novel methods, review articles, and book chapters. I have studied the visual system not just for the sake of understanding vision itself, but also as a model for how the rest of the brain functions. In recent years, I continued to work on the visual system and extended my knowledge of the visual system to cognitive domains, such as attention and numerical cognition. The population receptive field (pRF) approach has provided unique insights into a variety of neural, clinical, behavioural and computational questions.

Representative publications about vision


I mainly use brain imaging techniques such as functional magnetic resonance imaging (fMRI) at ultra-high field strengths of 7 Tesla, but also psychophysical, neurophysiological, neuropsychological and other brain imaging (e.g. DTI, MEG, EEG) approaches. The development of new data analysis techniques is an important part of my research. These data analysis techniques are inspired by biological models, and focus on extracting more information from the underlying neural population than "activity". With these new analysis techniques I aim to uncover unique perspectives on our brain and behavior.

Representative publications on fMRI at 7 Tesla
Representative publication on model-based fMRI (pRFs)

Main topics

My research is centered around three major themes. The first two focus on the organization and the functional properties of our visual system in healthy subjects, whereas the third focuses on the visual system under clinical conditions.

Organization of the human visual system

The brain is organized into separate regions implicated in different functional processes. The visual cortex contains many maps of the visual world. These maps cover the occipital lobe, and extend into parietal, temporal and frontal cortex. These visual field maps are linked to functional and perceptual properties of the visual system.

Representative publications

Functions of the human brain and perception

I am interested in many aspects of visual perception and cognition, ranging from motion and shape perception towards quantity perception and attention. These aspects also reflect the diversity of perceptual and cognitive tasks for which we rely on our visual system.

Representative publications

Visual system disorders, plasticity and stability

Clinical conditions may alter the organization and function of the human brain. These alterations can provide insights into both the clinical manifestations themselves as well as fundamental principles of the brain. In particular, I am interested in the degree of plasticity of the human brain, and focus on a variety of conditions that affect the visual system.

Representative publications
Last modified: 2023