Ben feels as if there is some sort of barrier or wall between himself and his environment, as if he was an outsider watching the rest of the world go by without him. he is also experiencing some extremely hostile and aggressive urges, perceptual distortions, and paranoia. he has most likely been using

PCP.

Explanation:

Phencyclidine, or PCP, is a synthetic drug that is used for its hallucinogenic effects. Among the psychological effects experienced by users,most of them are related to extreme changes in perception, such as a feeling of losing control over one's own body, "becoming one" with others or with the rest of the world, paranoia, aggressiveness, and feeling detached of one's own body or from the world, a condition also referred to as depersonalization. In our case, it's clear Ben is experiencing several of these side effects. While its usage is generally low, PCP, also known as "angel dust", has some very dramatic mind-altering effects, which gives it a terrible reputation.

answer; acquired mainly during early childhood;