The ability known as introjection is the mental act of absorbing the expectations and projections (the driving out of unwanted impulses) of others, which is done both verbally or nonverbally. It is a phantasmatic process and an ego-based internalization of objects from the external world, occurring undetected by our acute awareness. Introjection is haphazard and not always a good friend as it can allow insidious things to enter our hearts and minds when we are not careful. I take great interest in introjection during childhood years as they are our most impressionable and formative, and therefore very vulnerable years. 
It is introjection that enables you to declare “I am like this” (I have accepted this as part of me) as opposed to projection which is to say, “I am not like this.” Projection can be seeable when you encounter who or what you fear yourself to be and try desperately to deny. The classic example is a son who says, “I am nothing like my father.” Introjection and projection combine a foggy image of the world as it exists inside and outside of your mind. In one aspect, there are the introjected objects and parts of you that you recognize. In another aspect, there are things within that you try to disavow as you are unable tolerate them. And lastly, there is your core that is alien to yourself. “The subject is both inside out, and outside in.” Essentially, everything blurs together so much that you never can get a sweeping view of every part of yourself all at once. 
Attitudes, behaviors, emotions, and perceptions are the components of introjection regularly acquired from persuasive or commanding people in your life. No cerebration on these components takes place and they are not consumed slowly; they are quickly ingurgitated into your personality and transmuted into beliefs that you are convinced should be kept and behaviors that you think ought to be followed. I am led to believe that defeatist attitudes that manifest in adulthood could have introjection origins in childhood. And therefore, I think we should beware of the mental courses and predispositions we impose on our children as we endeavor to shape and mold them. 
The following scenario was adapted from a 2013 Psychology Today article: 
You are having your 7th birthday party. You are quite excited. Your parents have planned the whole event for you, inviting many friends of yours and theirs (adults of course). It is pizza, cake, ice cream, and candy du jour! The party is principally about you, but your parents’ persnickety behaviors about the decorations, attire, and their preferred invitees make it seem they are too concerned about themselves. Their brisk movements while setting everything up means they are self-conscious about how others might judge their party-preparing skills as well as their parenting skills. But that is not obvious to you, because you are 7 years of age and have your action figures, friends, and gifts preoccupying you. In the adult world, there is an unspoken standard of garish looks and appearances that your parents are trying to abide by.
As they are moving about the house you are still undressed for the occasion. So, your parents urge you to get dressed. The attire of Toy Story’s Woody is en vogue for the children among your clique, and you need to enchant your friends, so you grab the costume from your closet and put it on. Suddenly, some of the guests arrive prematurely and your parents have not finished preparing. Exasperated, they scurry even more to put everything together and must improvise to render the half-baked illusion of preparedness and creativity.
They see you proudly displaying your outfit and are rankled by your silly choice that adds to the long list of things gone wrong. Normally, if everything had been going according to plan, your parents would have felt fine about your cute pick, but they cannot withstand demurring, “Oh my! Son! Of all days to wear that silly outfit, today is not the day. You need to look presentable.” Your parents scowl at you even though they never specified what you should wear. They expected you to choose the right outfit and you felt confident that you would choose the right outfit to fit the occasion. But now you have lost your confidence. You wonder if you can pick the right clothing for any party or special occasion in general. You wonder if you are capable of exercising independence in this aspect of your life. What if your friends make fun of you because of your parents’ displeasure with you? Defeated, you feel that choosing clothing for yourself at all would result in rejection, unavoidably. So, why even bother? Later, your parents come to your bedroom and see you are still undressed 30 minutes after the premature arrival of the guests. Now, their exasperation increases.
The feeling predominating in you now is that you are dumb or incompetent. Neither of your parents said you are as such, but you sensed sullenness in their voices, and you saw their cringing facial expressions and their scurrying around to get everything done. Whether they meant it or not, they conveyed the feeling that you are dumb and incompetent.
Situations of this kind are normal. They occur in everyone’s lives. They can occur because of foibles or major flaws in our character or confusing situations, as adults. They can cause maybe a dent in our self-confidence, as adults. But for children the consequences are graver. This is an example of ostensibly mild and routinized household activity involving peevish parents and a young uncertain child. But if similar experiences with reproach and rejection happen too often, this can provoke unwanted thoughts and behavior patterns. 
A child can feel defeated even before he/she enters high school. Children are highly intuitive and receptive about nearly everything, whether good or bad. Children are like sponges, soaking everything into their identity that is directed at them. This is how they gain control in their environment while concurrently accepting what they think are their mirrors. Most importantly, those mirrors exist in the faces of their caregivers/parents, and they reflect not only who our children see themselves to be but also involve their fear of abandonment. They feel they must reflect what they see in their mirrors to keep their relationship intact with those they love.  If we agree with Hungarian psychoanalyst, Sándor Ferenczi (1909), introjection is an ineffaceable aspect of the whole nature of the act of love because it enables attachment. It also enables one to absorb the object of one’s love into the ego. 
Adults become desensitized to this through age, but every negative experience, even those slightly askew, can be devastating for a child as their sense of self is dragged beneath the undercurrent and they are forced to become whoever they think is in the mirror. Remember, whatever you project onto your child, whether you have extinguished the problem or not, gets integrated into the child’s identity while they have the undeveloped ability to abnegate those projections from your lording presence. 
Sigmund Freud is said to have discussed introjection and thought of it as a defense mechanism that is commonplace among psychologically healthy people. But it was Ferenczi who coined the term. 
Minimal thought is involved with a child’s assuming any aspect of the parents’ personalities or beliefs (e.g. political ideology, concept of right and wrong, or ideas about sex). Some mental health professionals posit that children exert introjection as a defense against the ill-effects of having absent parents or guardians. They unconsciously adopt the idiosyncrasies of a parent to give the illusion that some aspect of the parent is present even as he/she is physically unavailable. Introjection can produce positive or negative effects, determinedly by what attitudes are adopted. 
Introjection causes people to become so strappingly attached to a person or object that they cannot declassify themselves from that person or object. Becoming unduly engrossed with the beliefs of others instead of one’s own personal needs can become the cause of introjection. We sometimes find adolescents trying to carry the mantle of persevering their parents’ belief system, traditions, honor, and memory instead of systematizing their own beliefs and decisions about the future. Therefore, victims of abusive relationships are so inclined to internalize their partner’s contemptuous comments about appearance and behavior. So, they act and think accordingly. An abuse victim can introject the abuser’s pathology so intensely that the victim can later become an abuser. 
A personal example of introjection is this:
During my upbringing, my father worked in the trucking industry. He would often work long shifts and was not present for evening dinners nor to tuck me into bed. My mother often complained about this and talked about him in such a way that made me think he was a defective father/husband. He made $18+ per hour and I was led to think that is an inadequate wage based on their fear of losing sustenance. Though they never intended to impress it upon me, I was led to believe that a good husband is one who is home every night for his family and makes enough money to keep his family unafraid of losing their provisions.
I did not become fully aware of this belief until sometime during high school. While assessing this belief, I realize it is a good and helpful belief that a man should work and not be slothful, especially for his family. A man should strive to make an adequate wage. However, if I do not have the proper cognitive shema, my introjections can weaken my self-worth and make me feel inferior for not making a lot of money instead of making just enough.
It has been hard for me to accomplish that at my young age and hard to believe that $18 per hour can suffice when my parents repeatedly told me, “Son, make sure you get a good job when you get older and make sure you do better than me (your father).”
It has been hard getting rid of that burden of introjected lust for more wealth.
 Sex in Psycho-analysis: Contributions to Psycho-analysis, Sándor Ferenczi, pg. 77