Unsolved problems in cognitive science

There are fewer celebrated findings than unsolved problems in cognitive science; however one can list:
 * How much human intervention is needed to produce a cognition?
 * Why is it currently so much more difficult for a machine to recognize a human than for a cat to recognize its owner?
 * Why is the conceptual horizon wider for some than for others?
 * Might there be a relationship between the speed of cognition and number of eyeballs? What is its form?

Please add to this meager list. If some finding can solve an item on this list, please strike the formerly unsolved problem and put in a reference to its solution under the Category:Cognitive science.