Border-ownership reversals determine the strength of metacontrast masking.

Visual objects can be rendered invisible if their borders are assigned to other objects, showing that border-ownership (BO) is critical for perception. Objects can also be rendered invisible by using masking to limit the amount of time the brain has to process the object. An example of this is metacontrast masking (MM). MM occurs when an object is briefly presented and is followed by the presentation of a mask with closely adjacent contours. The mask can render the target object invisible, even though the target object is processed in high level brain areas. We propose that a critical factor that determines whether the target is perceived or not, is the amount of time that the target object retains ownership of its borders. What many MM paradigms have in common, is that when the mask appears, it reverses the directions of ownership at the borders of the previously presented target object. We hypothesized that this reversal in BO disrupts recurrent processing of the target object and impair perception. Here we tested this hypothesis by designing new MM paradigms with masks that either reverse ownership of the borders of the target object or not. We consistently found that masking was stronger when the mask gained ownership of the borders of the target object than when border ownership was unaffected by the mask. Our results indicate that prolonged ownership of borders is crucial for creating a stable model of the world, which enables the perception of stimuli.