Mmm. Without the distinction between top-down attention and bottom-up saliency, this is impossible to interpret.

For example Itti, Koch, and Niebur have papers on a simple attention model: https://ieeexplore.ieee.org/document/730558

You can not just do an experiment using top-down attention on one hemisphere and subsequently draw conclusions using a bottom-up salient object at the other hemisphere. At least not conclusions about the role of alpha waves in both - different (!) - scenarios.