The Effect of spatial frequency on phantom contour detection

Phantom contours are visual illusion that can define regions with distinctive boundaries when no real surrounding edges exist. Spatial frequency sensitivity varies reliably across the parallel processing pathways, as does temporal frequency sensitivity. Given that the effect of temporal frequency on phantom contour perception is known, two experiments were designed to measure the highest level of spatial frequency that would still allow for reliable detection of a pattern at different temporal frequencies. The findings seem to suggest that the underlying processing mechanism responsible for phantom contours might be related to the boundary detection system, which could be fed by the M pathway, although not exclusively. One possible clinical application for phantom contours involves specific reading disability (SRD) or developmental dyslexia. A number of researchers have made the claim that an SRD is a consequence of inefficient or inappropriate activity in the magnocellular pathway during reading tasks. These results were also examined in light of this magnocellular deficit theory. The relationship between dyslexia symptoms and sensitivity to phantom contours is discussed within both the magnocellular and boundary detection frameworks. The findings suggest that the mechanism responsible for the processing of phantom contours might also underlie global text pattern processing.