The Laws of Duplicate Bridge define a psychic call as "A deliberate and gross misstatement of honor strength or suit length."
A call is NOT a psychic if the definition given for the call is such that the person making the bid has not deliberately misstated strength or length. There are many situation where a psychic would be called for, but the partnership can avoid the psychic occurring by defining the bid to include the "psychic meaning." Why do this, though?
Consider a simple example. White on red, partner opens Three Clubs. After a pass, you bid 3NT, played as non-forcing and showing either a strong hand that thinks 9 tricks possible or a weak hand with club support. Opener is expected to pass throughout. You do this for two reasons.
First, if the hand belongs to the opponents at the game level, 3NT undoubled down 9 (-450) might beat 5CX-3 (-500), which is a matchpoints gain. So, 3NT undoubled is a good result. Plus, you cause the opponents to have a problem.
Second, if you really wanted to play 3NT, you might induce a mistake by an opponent if the remaining points are stacked. For instance, if you have 26 HCP combined, one opponent might have all of the remaining 14 HCP and bid, to his great discomfort.
By having a two-way meaning, each of which merits 3NT as a call, you protect both. Two-way calls in such situations avoid unnecessary disclosure of values.
Similarly, consider a 2S response to a weak 2H opening. If this is "spades, or hearts" and non-forcing, you cause problems when your intent is preemptive, but you also protect the times when you wanted to escape to 2S, as the opponents must bid against oth possibilities.
So, is this a "psychic control?" I don't understand that term, frankly. If a call is used to "show a psychic," then the "psychic" was not a "psychic" after all. That is, unless the definition of the call did not include the "psychic meaning." IMO, a "psychic control" is not really what it sound like. Rather, it is a means of conventionally agreeing a meaning that is not otherwise allowed (which would be a GCC problem and not a psychic problem) or is a means of allowing non-disclosure of the true meaning, which is really a disclosure problem (and/or a failure to alert).