What do we call it when we do something without even realizing it due to a developed habit?

Eg. Inserting the charger plug in the socket every time one switches the laptop on. One day, she realizes that she didn't even remember when she inserted the plug. Similarly, there are a lot of activities like this that get stored in our memory.

Solution 1:

The other answer uses the phrase Muscle memory. This is probably the best word I can think of for that. You would use it in a sentence like this:

"Propelled by muscle memory, she inserted the charger plug into the socket."

Subconscious is another good word. You use it like this:

"Subconsciously, she inserted the charger plug into the socket"

You could also use the word Absent-mindedly. This is when you do something without thinking about it properly.

"Absent-mindedly, she inserted the charger plug into the socket"

Those are all the words I can think of off the top of my head, hope it helps.

Solution 2:

See mechanical (ODOL)

2 (of an action) done without thought or spontaneity; automatic. ‘Most curious of all was the fact that he made the same mechanical gestures no matter what he was saying.’

And, why, you already called it a habit, haven't you? (Ibid.)

1.2 Psychology An automatic reaction to a specific situation.