Abstract
A remarkable feature of our brains is that they provide us with a perceptually continuous visual scene despite the constantly changing retinal images due to eye and object movements. Neurons in early visual cortex play an important role in interpreting scene structure by encoding border ownership of edges. Border ownership signals arise for attended as well as unattended objects (Qiu et al., Nature Neuroscience 2007). We have previously found a short-term memory for border ownership in the responses of V2 neurons (O'Herron and von der Heydt, Journal of Vision 2007): When a figure display switches to a split field that is ambiguous with regard to border ownership, neurons continue to signal border ownership according to the initial display for more than one second. The circumstances suggest that this persistence is independent of attention because we found it in monkeys that were trained to fixate a dot on the display and ignore any other visual stimulus. However, because the onset of a stimulus can capture attention, it is conceivable that border ownership signals are maintained by persistent attention. We examined this possibility by presenting two figures sequentially with the reasoning that each figure onset should capture attention, and so, after the second figure's appearance, attention should change to that location. After brief presentation, each figure was replaced by an ambiguous edge as described above. We found that the border ownership signal at the first figure did not drop when the second figure was presented and showed normal persistence. Reversing the order of presentation showed that border ownership signals persisted simultaneously at the two ambiguous edges. We conclude that the persistence of border ownership signals is not driven by persistent attention.