How would you define 'complex higher consciousness?'
Bear in mind that however I put this, it's not going to be accurate because the kind of consciousness I refer to is non-verbal, non-linear, and non-intellectual. Logic is something you apply to it later in order to attempt to deconstruct it for the sake of your rational mind, but initially it's a "knowing" that seems to come from nowhere.
The third eye contains the capacity to see Samsara for what it is: an illusion. It's all just Oneness, and Emptiness. A lot of people on a spiritual path feel like they have to work toward something, climb a spiritual ladder, and they go through periods of feeling disconnected and wanting to reconnect. An opened third eye (and more specifically, one that is open while the heart centre is also open) lets the observer become one with the object until the two are indistinguishable, which facilitates the awareness that there is no disconnect. There never was. You are always connected, forever, unconditionally, without any need for approval. There is no spiritual ladder, no here or there, no higher or lower. There is only Oneness.
Have you ever heard that quote?... the ocean becomes the drop, and the drop becomes the ocean. The drop contains the entire ocean, as well. Once you can unite duality in your mind, and hold the unified form without wavering, you'll probably unlock your third eye. It's really about duality and seeing through the illusion of separation.
Once that realization is achieved, other openings in consciousness begin to cascade. That's the best way I can put it. You'll know the openings are true and right because your heart will tell you so. It's not a logical exercise. There is no burden of proof, simply a "true" or "false" coming from the heart.
Basically, a third eye opening shows you that you are not your ego. It's sort of a depersonalizing experience, yet not... because you realize that there is a deeper "you" that transcends your temporal personality, and it's a "you" that is in everything and everyone around you. We are all the same thing.
Foreigner: Have you opened up your third eye?
My third eye has been open since I was born, evidenced by certain abilities I have. I wrongfully assumed my entire life that everyone could see the things I see, but I later learned through ridicule and this is not true. I can explain the third eye not because I had to work to open it, but because I had to do a lifetime of research to understand why I am the way I am. Turns out, nothing was wrong with me.
When a child is born, if you cover their eyes for the first three months of life, they will be blind forever. The visual cortex just loses its potential. Similarly, if you are born with a third eye that's open, I think your brain develops in adaptation to that. But unlike blindness, the third eye can be developed with practice. I just think I was a rare case.