Pupil Dilation
The pupils of human eyes dynamically dilate or constrict to admit a physiologically optimal level of light for the scene being taken in. Pupil dilation is autonomic and cannot be controlled at will; yet imagining certain scenes adjusts pupil size accordingly.
In all experiments, participants’ eye pupils dilated or constricted, respectively, in response to dark and bright imagined objects and scenarios. ~ Norwegian cognitive psychologists Bruno Laeng & Unni Sulutvedt
