Near complete interocular transfer of the attentional repulsion effect

During a brief period following attention capture by an abrupt-onset cue, a briefly presented item in the vicinity appears to be displaced away from the focus of attention. This effect, termed the attentional repulsion effect (ARE), can be induced with various ways of focusing attention (e.g., color pop-out, an auditory cue, voluntary focusing), and can be measured in various ways (e.g., as a vernier offset, shape deformation, action error). While most prior results on ARE have confirmed its close relationship with attention mechanisms, DiGiacomo and Pratt Vision Research 64 (2012) 35-41 reported no interocular transfer of ARE, placing ARE's operational locus at the level of monocular processing in V1 and/or LGN. DiGiacomo's and Pratt's result is surprising because even local pattern adaptation effects thought to be mediated by V1 show 50%-80% of interocular transfer. How could it be that a strongly attention-dependent effect is exclusively mediated by monocular processes? It was thus important to replicate DiGiacomo's and Pratt's surprising results using a transient-free mirror-based stereoscope and a broader method where ARE was measured with both vertical and horizontal vernier offsets. Our results demonstrate a nearly complete interocular transfer of ARE, with stronger ARE obtained with horizontal than with vertical verniers, implying that ARE may be hemifield dependent. We speculate that the null ARE result reported by DiGiacomo and Pratt in their dichoptic condition may be due to a statistical anomaly or to a potential visual artifact generated by the eye shutters that were used to present dichoptic stimuli.