From a psychological viewpoint, developing the sixth sense can be described as relieving the unconscious mind of some of it's responsibilities and entrusting them to the conscious mind.
The conscious mind has to undergo changes in order to accommodate these responsibilities. For a psychic, instead of not being perceptive enough, there is an additional problem - being too perceptive.
The psychic has to come up with new ways to structure his or her mind, or risk insanity due to an overload of data.
The concepts behind terms like 'perspective management' and 'structural integrity' may assist the psychic in creating the inner workings of one's mind.
Perspective management hopes to filter and sort the massive amounts of incoming data in such a fashion as to provide wholesome vision at a moments notice. A psychic with a developed sixth sense may flexible and focus her awareness at any point of the image which remains constantly in motion.
Previously when all of this work was left to the unconscious mind, the result was mostly like a yes-no answer: keep the information or discard it. By not investing effort to gain a wholesome vision, the view of the world of such a person is fragmented and not very flexible.
Structural integrity is the 'health' of the structure - in this case, the mind of the psychic. For a non-psychic, questions of the health of the psyche are left mostly to the unconscious. A psychic, with the greater influx od data in to the conscious mind, cannot afford that.
A psychic has to pay extra care to the structure of his or her mind, and make sure this structure is clear, strong, durable and flexible.
The sixth sense is not just another sense 'tacked on' to a human. It is the very essence of the clear individual who follows the path of the psychic.