Unconscious biases. It’s that automatic reaction in your head based on associations in your brain which are wired to take shortcuts and free up space. They are so hard to get rid off so the first step in the process is to get a point where you can simply catch yourself having these associations. My friend happily announce something and my first reaction when she said she had already done it was “woman equals irrational idiot, acting on the whim and excitement not thinking things through”. But that is not true I’ve seen plenty of guys act the same way it’s just stereotype that society has cultivated. And equally I have plenty of rational female friends making smarter and better thought out decisions than most guys. So I have caught myself with this thought internally correcting myself to say humans are sometimes irrational idiots because that is way more true.