A rather basic question, but I don't see answer in Google, so here it goes: Humans have thoughts, sometimes these thoughts carry with them motivations to act, urges, cravings, etc. All these can make a person start moving to accomplish something.
For example: "I'm rather bored, I think I will go get a snack". What happens the moment I cross the threshold from thinking to actually getting up to get a snack?
What happens the moment the person starts to act based on a thought? Where in the human brain does a thought trigger action?
Update: In response to an answer suggesting that in many cases action comes first and rationalization for action comes second:
The kind of action that I'm talking about comes after a longer period deliberation, where the current state is being weighted against the benefit of the action to take.
For example in the situations below, a person can deliberate for minutes:
- A person is in bed and is very close to sleep, being comfortable and relaxed. Loud noises from the outside disturb the person's attempt to fall asleep. In this case the person can experience conflict between staying in bed (comfortable but disturbed) or going to find earplugs / shut the windows (uncomfortable, but potentially lessening the disturbance)
- A person is trying to meditate, thus relaxing the body and unfocusing the mind. An itch on the foot is disturbing the meditation. Such person can either continue the current state while ignoring the discomfort or scratch the itch and potentially lose the meditative state.
In the examples above, two conflicting courses of action are evaluated by the brain. Due to the ongoing discomfort, it is possible to stay in this state of "almost making a decision" for quite some time. At a certain point the scale can tip into taking action to resolve the discomfort. What is it that causes the person to take action as opposed to inaction?