In the 1890s, psychologist George M. Stratton conducted experiments in which he tested the theory of perceptual adaptation. In one experiment, he wore reversing glasses for 21½ hours over three days. After removing the glasses, "normal vision was restored instantaneously and without any disturbance in the natural appearance or position of objects."
On a later experiment, Stratton wore the glasses for eight whole days. By day four, the images seen through the instrument were still upside down. However, on day five, images appeared upright until he concentrated on them; then they became inverted again. By having to concentrate on his vision to turn it upside down again, especially when he knew images were hitting his retinas in the opposite orientation as normal, Stratton deduced his brain had adapted to the changes in vision.
Stratton also conducted experiments where he wore glasses that altered his visual field by 45°. His brain was able to adapt to the change and perceive the world as normal.
In some extreme experiments, psychologists have tested to see if a pilot can fly a plane with altered vision. All of the pilots that were fitted with the goggles that altered their vision were able to safely navigate the aircraft with ease.