The human brain has phenomenal power in its ability to understand written language even when letters are scrambled, as long as the first and last letters of each word remain the same. Research at Cambridge University found people can still read sentences where interior letters are scrambled because the brain processes words holistically rather than individually. Optical illusions demonstrate how perception is influenced by expectations and prior experiences rather than objective reality, as some images play tricks on the brain and appear to move or change when in fact they are static.