Too many ads.

I find that I randomly buy things that I have seen in ads without even realizing it. It's scary because I absolutely hate ads. What is going on with my brain?

Many things, are you asking why you specifically you as a person, buy them? Why ads work in general? Why the products you bought from ads stick with you while you forget all the ones you bought that weren't advertised?

These are all mental oddities.

Last one is called confirmation bias.

I too have a desire for many things which I see in ads.

Its probably due to desire to try new things.

I find it eerie that I am not even aware of my shopping choices until after the fact. I don't like thinking that big companies have that much control over my choices.

They succeeded in suckering you in or in marketable terms, successfully added you to their conversion rate.

That's on you.

They didn't do this to you. They didn't brainwash you against your will. You have welcomed it in and choose to base your decision on the first impulse of what to buy without conscious filtering of it.

Discipline takes effort. I am not saying you are wrong to not let loose and go 'whatever' and not go for the best value for money each time, I am saying blame yourself alone for relaxing your brain when you buy things.

So I just need to think more when I buy things.

You just need to think more about that statement.

If you don't actually need it, then don't buy it.

Homer Simpson would probably buy, and think it simultaneously.

D'oh.