Research in the lab

Our research focuses on the neural processes of interpretation and selection that allow sensation (the retinas detecting light) to turn into conscious visual perception (seeing). We approach this topic using a diverse array of techniques from psychology and neuroscience, including psychophysics, brain imaging (fMRI), computational modeling, eye tracking and brain stimulation (TMS).

Perception is a cognitive act. It happens when stored knowledge and intentions engage with the information that currently enters through the senses. This is why a person's eardrums or retinas, which contain little in terms of knowledge or intentions, can be said to sense but not to perceive, whereas the person as a whole perceives. Our research centers on the interactions in the brain that construct conscious visual perception out of retinal input. One way of summarizing these interactions is in terms of interpretation and selection.

Seeing is interpreting. We do not perceive the pattern of excited retinal receptors that form the actual input to our visual systems, but rather we see conjectured scenes in front of us. In a process that Hermann von Helmholtz called 'unconscious inference', the brain matches retinal signals with knowledge about the world, and perception reflects the brain's most plausible hypothesis as to what scene may have given rise to these signals. In our research we investigate this interpretative aspect of vision by presenting observers with ambiguous or conflicting visual input (see movie): input that could plausible have arisen from any of several real-world sources. This approach provides an exceptional window into the visual system trying to find an interpretation and, indeed, switching between interpretations over time even though the input stays the same.

Seeing is also selecting, and this selection side of vision reveals links with planning and the control of action. This applies, in particular, to the process commonly designated as selective attention: in motor areas of the brain a person's focus of attention is often indistinguishable from the target of that person's planned movements, yet selective attention also influences even the most peripheral visual brain areas. In fact, by filtering out parts of the visual input and highlighting other parts, selective attention determines what we perceive and which input remains outside of our awareness. A main component of research in our lab is aimed at understanding the processes by which selective attention influences visual processing and perception.