Abstract
In two experiments we used bilateral and unilateral backward masking to investigate the time course of a a rectangular target's surface completion. Our results show in both the bilateral and unilateral masking conditions that surface completion proceeds as a “filling out” from the interior middle region of the target toward its edges. Both masking procedures yield similar estimates of a filling-out speed at about 25 deg/sec in retinal coordinates, a value about 20% of the filling-in speed reported in prior studies. Moreover, using the relationship (based on human cortical magnification estimates) between retinal distance and cortical distance, our results show that the cortical filling-out speed proceeds at about 0.4 m/sec. Using Watt's MIRAGE model, we offer an explanation of our results in terms of a spatiotemporal process of filling-out by progressive filling-in.