Comment by alanbernstein

I doubt it really takes that much brain power to move around complex environments, even using legs. Insects manage to do it.

> Would a baby that grows up in a sensory deprivation tank, but is still able to communicate and learn from other humans, develop in a recognizable manner?

I don't think so, because humans communicate and learn largely about the world. Words mean nothing without at least some sense of objective physical reality (be it via sight, sound, smell, or touch) that the words refer to.

Hellen Keller, with access to three out of five main senses (and an otherwise fully functioning central nervous system):

    Before my teacher came to me, I did not know that I am. I lived in a world that was a no-world. I cannot hope to describe adequately that unconscious, yet conscious time of nothingness... Since I had no power of thought, I did not compare one mental state with another.

    I did not know that I knew aught, or that I lived or acted or desired. I had neither will nor intellect. I was carried along to objects and acts by a certain blind natural impetus. I had a mind which caused me to feel anger, satisfaction, desire. These two facts led those about me to suppose that I willed and thought. I can remember all this, not because I knew that it was so, but because I have tactual memory. It enables me to remember that I never contracted my forehead in the act of thinking. I never viewed anything beforehand or chose it. I also recall tactually the fact that never in a start of the body or a heart-beat did I feel that I loved or cared for anything. My inner life, then, was a blank without past, present, or future, without hope or anticipation, without wonder or joy or faith.

I remember reading her book. The breakthrough moment where she acquired language, and conscious thought, directly involved correlating the physical tactile feeling of running water to the letters "W", "A", "T", "E", "R" traced onto her palm.