A change of mind that's well documented, and that people often describe, is the one about multitasking and attention. For years many of us believed that working on several things at once was a skill we could train into ourselves. Research from the 2000s, including Stanford work by Clifford Nass and colleagues, found that heavy media multitaskers did worse on tests of filtering irrelevant information and switching between tasks, not better. That finding changed a lot of people's habits, though later studies have complicated the picture: some people appear to be better at multitasking than others, and the effects vary by task.
What I find interesting is how the change usually happens. It's rarely one study. It's a slow pile-up of small experiences, like noticing you reread the same paragraph three times after checking your phone, until the old belief stops fitting what you've seen yourself.
What's a belief you once held firmly that gave way, and what was the moment it started to crack?
