The lemon became real for you; your imagination tricked your body into believing it would have to cope with a mouthful of pure citrus.

Harry decided that his imagination had tricked him.

It was a grim reminder of the past - so grotesque that, for the moment, Harry thought his imagination was tricking him.

Thorden decided that his imagination must have tricked him.

Then he realized his imagination had tricked him.

Then she realized that her imagination must be tricking her.

A short laugh escaped his lips when he decided that his imagination was tricking him again.

Completely flabbergasted by the way his imagination had tricked him, Steve subsided without further resistance.

She was sure imagination had not tricked her.

If his imagination was tricking him, then he didn't want other people to know about it.