over time the choices of predictable limited selection of input reinforces itself by strengthening established connections in the brain and habituating actions to strengthen them further. a good example being someone who has listened to classic rock radio for the last 30 years, about the same 50 songs every day. when exposed to new stimuli there will be a noticeable agitation or outright rejection of novelty. i have also noticed this in people who have only watched TV news or read the same newspaper over an extended period in their life, when exposed to unfamiliar themes from a different news source. conclusion, seek novelty, even if it creates discomfort, if you want to continue to have the physiological hardware to remain open minded.