Feels empirically true. I remember cases where I thought about a memory and was initially uncertain about some aspect of it, but then when I think about it later it feels either true or false in my memory, so I have to be like, "well no, I know that I was 50/50 on this when the memory was more recent, so that's what my probability should be now, even though it doesn't feel like it anymore".
Seems like the fact that I put about a 50% probability on the thing survived (easy/clear enough to remember), but the reasons did not, so the probability no longer feels accurate.
One bit could also encode "probably true" and "probably false". It doesn't have to be "certainly true" and "certainly false". And this is of course what we observe. We aren't perfectly certain in everything we can barely remember to be true.
Our memory tends to contain less and less information. We forget certain things, and our memory about others become simplified, and a complex article boils down to “X is bad, Y is good, try to do better".
One unexpected consequence of this is how it impacts our sense of probability: to describe the probability binary, it only requires 1 bit of information, but to describe the probability as a percentage, you need a lot more bits!
Because of this, a person's confidence in the most likely hypothesis in his opinion tends to 1 over time, and the probability of all other hypotheses that he had time to think about tends to 0. Every time he remembers a hypothesis, a person will less and less often remember the nuance that “the probability of hypothesis A = X”, he will simply remember “And this is the truth (that mean the probability of A = 100%)”.
Every time you remember a hypothesis, this effect contributes. Therefore, just after thinking about a hypotheses, you should write down your confidence. Also, you should to remember this bias to notice it, when you use a hypothesis you thought a lot of time ago.
PS: memory is bad, writing is good, try to do better.