The action of thinking about two different subjects or ideas while attempting to communicate, usually resulting in communications failures.
Person A: I just hit a deer.
Person B (Thought 1): Did it have antlers? That would be a buck.
Person B (Thought 1): I hope you avoided getting hurt. I probably would have ducked.
Person B: Was it a duck?
Person A: No, but I wish it was.
Person A: I'm sorry, I was split braining there.