Mental operations are processes that modify whatever is situated in our mind.
It is extended among most of the logicians that every learning pattern involves three fundamental and basic mental operations: apprehension, judgment, and inference.
The first one, apprehension, has to do with the understanding; it is the operation by which an idea is created in the brain. Let´s say you want to imagine a nice sunrise. What you need is this process taking place inside your head to make that idea appear. So anytime you need to picture any scene or thing in your head, apprehension is what is going to happen.
The second, judgment, is the mental operation by which we create an opinion about something or someone: it can be a person or a subject. Through this process we make statements. Let´s say you have a thought regarding the sunrise you just saw, by talking about it you would be making a judgment.
And the third one, the inference, is the process through which you get to conclusions based on information taken from somewhere else. It's the reasoning. Let´s say you come to the conclusion you really like that sunset you just saw because you also like some other nice things in life and declare it´s beautiful, you would be reasoning.
Each one of them has its own verbal expression: for the apprehension is the term, for the judgment is a statement and for the inference is logical reasoning.
At the beginning, these processes were studied only by one discipline, the Logic, but later on it got popular in the Psychology field as well.
