I have been wrestling with this today, and have found it difficult to grasp what actually going on during the decision-making process. I made the following observations, sorry for the length:
The relationship between thoughts and actions
1) A thought appears as an image-thought or talk-thought.
2) A desire arises as a feeling-sensation or a talk-thought “I really want this or that”.
3) A decision is made as a talk-thought “I will do this or that”.
4) Action is taken
5) (Sometimes) a talk-thought arises “I did this or that” after the action, or an image-thought arises of myself performing the action.
A couple of other notes:
A decision appears to be actually made, however the decision is just a thought. Likewise, the other parts of the process are thoughts or sensations – the content “I” isn’t real – like the imaginary watermelon experiement. A thought may arise after the action that says something like “I did this or that” that makes it appear that an I decided to perform an action. In other words - (5) fills in in the gaps.
Thought (5) doesn’t always appear. Sometimes I perform habitual actions that are not claimed by the I-thought. Sometimes thought (5) doesn’t appear until hours after the action has been performed. But in remembering the action, thought (5) claims “I did it”.
Here’s a couple of practical examples I noted today.
Example 1. Filling up the birdbath in my garden
1) See the birdbath (Seeing-Sensation)
2) “The birdbath is dry” (Talk-thought)
3) “Shall I refill the birdbath?” (Talk-thought)
4) “I will refill the birdbath” (Decision / Talk-thought)
5) Refill the birdbath (Action)
6) “I filled up the birdbath” (Talk-thought sometimes accompanied by image-thought)
Example 2. Waking up hungry and eating a bowl of coco pops
1) Hunger (Sensation)
2) Image of coco pops (Image-thought)
3) “I would really like some coco pops” (Desire Talk-thought)
4) “I’m never going to get back to sleep unless I have some coco pops” (Talk-thought)
5) Anxiety about not getting enough sleep (Feeling-sensation)
6) “Should I get a bowl or stay in bed?” (Talk-thought)
7) “I’m going to get a bowl of coco pops” (Decision / Talk-thought)
8) Eat coco pops (Action)
9) “I ate a bowl of coco pops, now I can sleep again” (Talk-thought)
Example 3. Being asked what to drink
1) ”I am making a hot drink, would you like a cup of tea or coffee?” (Question)
2) “No thanks” (Answer)
3) “Actually I would quite like a cup of tea” (Decision / Talk-thought)
4) “Actually can I have a cup of tea please?” (Question)
5) “Okay” (Answer)
6) “I chose to have tea (but could have had coffee)” (Talk-thought)
Do you sometimes do something unconsciously, and then have a thought that you decided to do this or that?
Yes, for example I did some hoovering the other day apprently completely unconscios. It was only when packing the hoover away that there was an after-thought "I just vacuumed the lounge".
Do you ever start to do something, then become more conscious of what you're doing and change your behavior?
If you mean like realizing halfway through dinner that I'm wolfing my food down in front of guests, then yes I change my behaviour accordingly when I become more conscious of my actions.
I'm still looking at this, I think I need to examine a few more day to day decisions - especially regarding the last couple questions you asked - but this is what I can see so far.