Eli5: Why do you salivate just thinking of something acidic/sour?
In: 3
Your produce saliva as a reaction to acid to dilute the acid and prevent damage to your teeth/throat, it’s an automatic reaction.
Obviously producing the saliva *after* you’re eating the acid doesn’t really help so the brain is wired to predict the acidity *before* you eat it and generate the saliva. Of course it’s a better than the alternative especially since producing saliva isn’t really bad for you, it’s not like there is a detriment to a little bit of mouth juice.
Many reactions can be triggered by “_thinking_”. Shivering. Erections of various “tissues”. Crying. Feeling sick (Nocebo). Feeling well (Placebo). Why would _just thinking_ not be enough for this one situation?
Pavlovian conditioning. Your body learns through experience that sour foods cause these reactions. Eventually, the mere sight, smell, or even thought of such foods causes the physical response.
Tl;dr- Your brain hacks your body.