Then again, they might be... This kinda goes back to the question I once asked about which arm mercs routinely raise between their eyes. But even if they do show a preference, how does that relate to "complexity of the brain?"
I have always heard that Lefty's (sorry Thales) were more logical than Righty's and I am prone to agree so if Octo's too are in their "right" minds maybe there is something implied. The idea that there might actually be a left/right option seems to imply a higher level of brain ability but the thought is conjecture only.