Four-year-old tommy notices that every time his baby brother cries, his mother picks him up and holds him. tommy quickly learns that if he also cries he will get his mother to pay attention to him. his behavior resembles the choices made in the bobo doll experiments in the sense that his baby brother's behavior is and therefore tommy is more likely to it.

I believe the answer is: reinforced; imitate

Before we develop the cognitive abiltiy to understand abstract concpet (which mostly happen between the age 11 - 16 years old),  we rely on observing and imitating the people around us as our method of learning.
In the case above, tommy's behavior is reinforced by observing how his brother obtain the affection from his mother, which make tommy to imitate the crying act.