A few years back, I had an incredibly vivid dream that seemed to be real. One of the characters in the dream informed me that my whole life had been a dream, and I didn't believe her. We got in an argument, where I pointed out how vivid and detailed my surroundings were, how vivid and detailed my memories of growing up in California were, and how unlikely it was that a character in my own dream would disagree with me. The character challenged me to try to open my eyes, and I did, confident that they were already open. I opened my eyes, and it was 3:00 in the morning in my little apartment in Texas. I have never even been to California. My entire life had been a dream, and a small fragment of my subconscious had known it was a dream when I had not. I was a solipsist for the rest of the week.
I suspect my dad prevented this glitch from forming in my young mind. When I was a child, one of his favorite ways to tease me was to stand over me, and demand that I float in the air. He'd raise his hands over my head and pull them up, all the while saying "float! float in the air!" Of course I'd laugh, and I knew it was impossible, but I'd still try I'd strain, and rise up on my toes, and jump up and down, but I couldn't do it. Then he'd shake his head, and admonish that I'd better learn soon, because it would be too difficult to learn when I was "old and fat" like him.
The part of my brain that knew it was impossible would laugh, but a part of my brain would still try with all it's might to float, and quickly learned that it's impossible. Flying dreams are pretty difficult for me, now. I still find myself straining the way I did when my Dad commanded me to float.
It was pretty easy, once I thought about it a little. First of all, within the context of the dream I had, there had been a way to test whether I was in the dream- I just tried really hard to open my eyes. Granted, it wasn't a very good test. It's not always easy to wake yourself from a dream, and there's not much one can try if this fails, but it had worked.
Ultimately, I just told myself how useless solipsism is in a real-world context. We might all be trapped in the matrix, but if there's a way to test whether we're in the matrix and get out, then there's a way to define and test reality, and if there isn't a way to test if we're in the matrix and get out, then there's no reason to call what we're in anything but reality and accept the parameters of our shared experiences. In the latter context, saying that we might all be in the matrix doesn't predict anything or help us accomplish anything.
The most useful part of my experience was also what I found the most disturbing- that a piece of my subconscious knew something that my stream-of-consciousness self did not. It's a little humbling to be shown how much is going on in my brain that I'm not in on or aware of. I'm a lot less likely to trust my own perceptions, now.