In this topic we are dealing specifically with tricks where the amount of pressure imparted on the pen dramatically changes the allure of the trick.

http://media.putfile.com/Pressure-64-80

In the above example, the first time I do the trick, I only apply light pressure with the thumb downwards. The result however is a CW spin.

In the second time, I apply more pressure, also with the thumb downwards. The result is a CCW spin, the opposite of the first time!

The idea is that in the starting position of both tricks, the pen is held by 3 elements: the index, the thumb, and the "palm area" at the base of the thumb (thenar eminence).

When you apply pressure downwards with the thumb, the palm applies a resistance back. If the pressure by the thumb is too light, the resistance by the palm acts with a spring-like mechanism to impart a spin in the reverse direction than what the thumb was directing the pen at. If you do apply enough force, the thumb pressure breaks the resistance of the palm, dictating the motion of the pen in the "correct" direction.

A similar example can be done using the regular TA. Light pressure will impart a reverse rotation on it. It is hard to execute though.

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