The Gap Chart is a very simple model of the mind.
From our environment, we get various sensations – the light reflected off the paper you’re reading this on, the sounds around you, the feeling of the chair you’re sitting in, maybe some lingering tastes from what you last ate or drank,….
Each of these sensations has qualities. A taste might be bitter or sweet. A light might be bright or dim. A touch might be rough or smooth. In particular, these qualities may be pleasant, unpleasant or neutral.