Fragmentation of fixated line stimuli as a function of gravitational orientation

The differential propensity of fixated line stimuli to fragment and disappear from view was studied as a function of the gravitational orientation of the stimuli. The propensity to fragment was measured in terms of three intercorrelated dependent variables: the number of fragmentations per fixation period, the total duration of fragmentation per fixation period, and the latency to the first fragmentation. Unlike some anisotropic visual phenomena, which may reflect orientation-independent aspects of pattern perception, the observed anisotropy of propensity to fragment can be attributed overwhelmingly to the retinal orientation of the stimuli. Accordingly, this property of fragmentation need nof be ascribed to higher order aspects of pattern perception.