Stradlater; Ackley, who fabricates his sexual exploits; and his teacherMr. Spencer, who displayed his sycophancy when Headmaster Thurmer entered his classroom:

Old Spencer'd practically kill himself chuckling and smiling and all, like as if Thurmer was a goddam prince or something.

He feels that Phoebe represents the goodness and honesty of children. But, after listening to his criticisms, she scolds her brother, telling him that he does not like anything that happens. He counters that he likes Allie and he likes sitting with Phoebe and talking. Phoebe reminds Holden that Allie is dead, suggesting that her brother cannot deal with the present. Certainly, Holden longs for the innocence and sensibleness that he believes existed in the past and in his childhood. For this reason, he wants to be a "catcher in the rye," grabbing children before they fall over the cliff of adolescence into the hypocritical world of adults.

Holden definitely feels caught between childhood and adulthood because he's practically an adult physically and mentally, but in many ways he is stuck in the past. Holden hasn't fully dealt with his younger brother's death, so he obsesses over that. Plus, he suffers from anxiety and depression about what's happened in the past and what he faces in the future. Becoming an phony adult scares Holden to death, too. He doesn't want to grow up and be fake like the adults he sees around him. Because Holden is in limbo between childhood and adulthood, he gets caught in bad adult situations, asks difficult child-like questions, and has unrealistic ideas about the future.

First, Holden knows how to spend money, catch a cab, and get a hotel room like an adult, but he sure doesn't know how to handle shady people like a pimp and his girl. Holden accepts a guy's offer to send a girl to his room for $5.00. When she gets there, Holden can't go through with it and just ends up wanting to talk. That's one example of Holden not being ready to do adult things; but when the pimp comes back, he is cheated out of $5 more, beat up, and left to learn a lesson on the hotel room floor. Holden describes his caught in limbo feelings as follows:

"I wasn't knocked out or anything, though because I remember looking up from the floor and seeing them both go out the door and shut it. Then I stayed on the floor a fairly long time. . . I thought I was dying. I really did. I thought I was drowning or something. . . I sort of started pretending I had a bullet in my guts" (103-104).

Holden can't deal with reality like an adult, so he does what a child might do and pretend to believe the worst.

Another example where Holden expresses his caught-in-limbo feelings is when he asks cab drivers about what happens to ducks during the winter when the water freezes. This drives the cabbies insane to a point, but it is typical of a child to ask such a polarizing question. The cabbie, though, tells Holden that the fish just stay in the frozen water and wait till spring. From this discussion, a parallel could be drawn between what the cabbie says about fish and Holden because both are caught in a time of life when they don't have control over their life's situations. Both a fish and Holden must patiently wait for the spring to thaw the ice before he can move forward in life (82).

Finally, Holden is still idealistic and not facing reality like an adult should. Instead of planning his future and making plans for college and career, Holden tells Phoebe that he just wants to catch kids from falling off a cliff. He tells his sister the following:

"Anyway, I keep picturing all these little kids playing some game in this big field of rye and all. Thousands of little kids, and nobody's around. . . except me. What I have to do, I have to catch everybody if they start to go over the cliff. . . That's all I'd do all day. I'd just be the catcher in the rye and all. I know it's crazy, but that's the only thing I'd really like to be" (173).

Holden, at 16, is not ready for adulthood. He has a mental breakdown and luckily ends up in a hospital in California. He needs to deal with the many issues from his childhood before he can move onto adulthood. Hopefully, the hospital experience will help him to overcome his guilt and anxiety felt in childhood.

Holden attempts to act like an adult when he visits the home of his aging professor, before he leaves Pencey Prep. He takes the advice given to him, however begrudgingly, but basically sits and listens politely. He does not put up much argument when he is told to make something of his life (I can't remember the professor's name, but it occurs in Chapter One.) He also attemps to act like an adult in a similar way when visiting Antolini, near the end of the novel. He listens, but his throbbing head and overall depressed attitude make it impossible for him to really focus on Antolini's words. To answer the other part of your question, one of Holden's most obvious demonstrations of immaturity, or "acting like a child" is during the scene with Sunny the prostitute. He is punched in the gut by her pimp, and suddenly he is pretending that he was shot, just for fun. Holden also enjoys visiting the museum of natural history, as it reminds him of his childhood (a place Holden longs to be but is cognizant at some level that he cannot go back, hence the depression.) What emotional impact do these places/scenes have on Holden? Like almost everything in the novel, the impact is that of depression. Holden is depressed at every turn. He can't go back and he can't go forward, and he knows it.

For Holden, in an "ideal" world, everyone is still a bit naive about life.  Holden wants to protect children from having to face the harsh realities of life (thus his desire to be a "catcher in the rye").  He seems to feel so protective of others based on his own distorted perspective of the world.  He hates the falsity of other people, for example his school (Pencey Prep) which advertises its ability to turn out extraordinary young men, but all Holden sees around him is liars and thieves.  He sees his prep school as a microcosm of New York City, which is full of degenerates. 

Holden's parents, too, show his disdain for adulthood with their cocktail parties and high ranking social position.  They don't "parent" Holden, rather they just send his off to one boarding school after another.  There is no communication between parents and son.  Holden's sister Phoebe, however, reflects the honesty of childhood.  She says what she thinks; she is unafraid to confront life head on.  Adults seems to lose the ability to be honest and forthright about things.  Holden hates that about the process of growing up.

In an "ideal" world, people would always be honest and true, not a bunch of phonies.

As a 16/17 year old boy, Holden was in that grey area where, although still young enough to be considered a "child" he really was having adult thoughts and experiences.  Such as the loss of his brother Allie which marked him with a sense of deep grief that he could not come to terms with in any way.  This fuels he belief that childhood must be the last frontier of innocence in life, and why he labels all adults phony.

His observations of adult behavior leads him to feel that he would rather remain a child, in conjunction with the fact that he longs for the past when his brother was alive.  He has a remarkable ability to understand human nature, and questions the meaning of life more than a normal 16/17 year old would or should.  This leads Holden to become trapped in his thoughts instead of living in the present moment.

Holden is plunged into a serious identity crisis after his brother's death, that is when his problems begin, Allie died three years ago in the novel, just when Holden started high school.  He has failed out of all the schools he attended because he is caught in a cycle of grief from which he cannot escape.

Sadly his commentary on childhood is distorted by his mistaken perception that it is a time of carefree fun.  Children have responsibilities, they go to school, and parents expect them to get good grades as they travel up the academic ladder right through high school and college.

Holden is not trying to behave like an adult, he is a confused, deeply troubled young man who needs psychiatric help to sort out his feelings of deep loss over his brother, to understand his purpose in life and to accept that life presents continuous challenges to each of us, death, loss, disappointment, no matter what it brings, each of us is required to cope and move past our loss, sadness, grief and embrace each day of life.

Holden saw in children the lost world of carelessness and innocence that he consistently mourned and missed as a result of "growing older", yet, as we know, Holden never really has "grown UP". Holden was very much a child, but most importantly, he was an immature one at that.

His little sister was apparently the only person he seemed to respect, and listen to- almost as if he let her lead him psychologically because he felt safer around her than around people his age or older.

His idea of childhood is almost as if it were something to protect, though he cannot protect the children "from growing up". He does value it, immensely, and he mostly does so because in the world of the "grown ups" the phoniness and need for responsibility are too much for him to handle.

He says, after all:

I keep picturing all these little kids playing some game in this big field of rye and all.... If they’re running and they don’t look where they’re going I have to come out from somewhere and catch them. That’s all I’d do all day. I’d just be the catcher in the rye and all. I know it’s crazy.