A somewhat surprising result of this lateralization is that WM capacity is largely independent between the two visual hemifields. WM has a very limited capacity for holding multiple items at one time (Luck and Vogel, 1997, 2013). However, in both monkeys (Buschman et al., 2011) and humans (Delvenne, 2005; Umemoto et al., 2010), even when capacity is saturated in one visual hemifield, additional items can be stored in WM if they appear in the opposite hemifield. Similar effects of hemifield independence have been observed with spatial attention (Alvarez et al., 2012) and attentional tracking of moving objects (Alvarez and Cavanagh, 2005). This strong hemifield independence, however, seems inconsistent with the apparently seamless nature of visual WM. Our results provide a possible resolution to this paradox. They suggest that, in such situations, the two prefrontal hemispheres briefly sync up using theta and beta oscillations in order to physically transfer a WM trace from one cortical hemisphere to its new location on the retinotopic map in the opposite hemisphere.
