Constructing surfaces and contours in displays of color from motion: the role of nearest neighbors and maximal disks

Color-from-motion displays consist of a sparse array of dots which never move but change color according to various algorithms. Yet such displays can trigger human vision to construct apparent motion of a subjective surface which is uniformly colored and bounded by a subjective contour. We show that the perceptual strength of this construction depends on the density and regularity of dot placement. We studied three objective measures of density and regularity: nearest-neighbor distance, mean of maximal disks, and variance of maximal disks. We found that nearest-neighbor mechanisms alone are inadequate to account for the perceptual strength of the subjective surfaces and contours. Mechanisms sensitive to areal gaps provide a more adequate account.     

Utilizing Participatory Mapping and GIS to Examine the Activity Spaces of Homeless Youth

Although previous studies have informed our understanding of certain aspects of youth homelessness, few studies have critically examined the spatial and social environments utilized by youth as they navigate life on the streets. This study employed participatory mapping and Geographic Information Systems (GIS) to examine the activity spaces of homeless youth as they relate to sense of community and psychological well‐being. Participants were 28 youth experiencing homelessness in Portland, Oregon, USA. Results suggest that youth engage most frequently in service‐related activities, and their activity participation is significantly associated with sense of community and psychological well‐being. The utility of innovative participatory methods for better understanding the diverse experiences of homeless youth is discussed alongside examination of their practical implications.