Another way to think of expo is view it as if you were walking up a ramp to a fixed point. With no expo the ramp would be at a 45 degree angle from beginning to end.
If you add expo to soften the control around center the rate of change of the ramp would be less than 45 degrees at the beginning and become greater than 45 degrees at the end.
If you add expo to make the control more sensitive around center the rate of change of the ramp would be more than 45 degrees at the beginning and become less than 45 degrees at the end.