I still remember the day a simple thought experiment held me captive. I was 6 years old. I should have been at kindergarten, but I faked being sick, so I wouldn't have to go. I faked being sick a lot and either my mom was really gullible or she played along for reasons of her own.

I was thinking about a conveyor belt, such as was on my grandpa's treadmill. Then I imagined a projector screen in front and then also to the sides. Then I imagined a treadmill that could move in any direction , and next I imagined I was in a box on such a treadmill, but the treadmill became earth and the projectors imitated the scenery so perfectly that it was impossible for me to tell the difference.

At that point I realized I might be in such a box and I might be the only real person. Or that I was in the box, and there were other people outside of the box watching me live my life in the box. The thought scared the hell out of me and I decided to go find something else to do, rather than the think about it anymore.

Touch or the ability to grasp objects never occurred to me as a way to disprove the simulation at the time. This would have been 1980 or 1981, before holodecks on Star Trek TNG. Well before the Matrix of course. But as each of these different iterations of the simulation came into existence via popular sci-fi it reminded me of the day a simple thought experiment had me staring into the abyss, and the abyss stared back.