An essential task for our brain is to organise the large amount of information coming from our eyes into meaningful perceptual units. For example, our brain needs to decide whether two types of texture belong to the same object. Edges or contours are very helpful in segregating objects from each other. I have studied the brain mechanisms behind texture and contour processing.
I use psychophysical experiments. In these experiments, I show healthy people and stroke survivors artificial textures and contours that only differ in one aspect like orientation or spatial arrangement of the elements. For instance in the third image, you can see how the small white elements can follow the orientation of the contour (‘snakes’) or are orthogonal to the orientation of the contour (‘ladders’). I found that people use different brain mechanism for ‘snakes’ and ‘ladders’ when asked to judge the shape of the contour. Textures can be regular, like a brick wall pattern, or irregular, like stones on a beach. My experiments demonstrated that the spatial arrangement plays a role when judging the shape of an object, but not when judging whether a texture is regular or irregular.
Flemish Government – Methusalem programme
Prof Johan Wagemans – University of Leuven
Prof Glyn Humphreys – University of Birmingham (passed away in 2016)
Schmidt, F., & Vancleef, K. (2015). Response priming evidence for feedforward processing of snake contours but not of ladder contours and textures. Vision Research, 126, 174-182. https://doi.org/10.1016/j.visres.2015.03.002
Vancleef, K. & Wagemans, J. (2014). Component processes in contour integration: A direct comparison between snakes and ladders in a detection and a shape discrimination task. Vision Research, 92, 39-46. https://doi.org/10.1016/j.visres.2013.09.003
Vancleef, K., Wagemans, J., & Humphreys, G. (2013). Impaired texture segregation but spared contour integration following damage to right posterior parietal cortex. Experimental Brain Research, 230(1), 41-57. https://doi.org/10.1007/s00221-013-3629-7
Vancleef, K., Putzeys, T., Gheorghiu, E., Sassi, M., Machilsen, B., & Wagemans, J. (2013). Spatial arrangement in texture discrimination and texture segregation. i-Perception, 4, 36-52. https://doi.org/10.1068/i0515
Machilsen, B., Novitski, N., Vancleef, K., & Wagemans, J. (2011). Context modulates the ERP signature of contour integration. PLoS One, 6 (9), e25151, 1-7. https://doi.org/10.1371/journal.pone.0025151
Sassi, M., Vancleef, K., Machilsen, B., Panis, S., & Wagemans, J. (2010). Identification of everyday objects on the basis of Gaborized outline versions. i-Perception, 1, 121-142. https://doi.org/10.1068/i0384