In five years the topic from psychology 1001 that I will most clearly remember would have to be the effects of language deprivation in extreme situations. Specifically the story of a girl named Genie will never leave my memory bank. This poor girl was malnourished, abused, and deprived of social contact with people for 13 years. She is a living example of the effects of language deprivation.
Genie was found in a basement in 1979 chained in a back room. She could not speak or perform basic social norms. The following youtube video explains the situation in depth. This video is the first of 8 youtube videos from the PBS series nova. If you would like to watch all of the links on the side will assist you.
While this situation is extreme there are other cases of language deprivation that happen all the time. Children who suffer from hearing loss or who are fully deaf who live with hearing parents are in a similar situation. Generally, the parents will invent a homesign which according to Lilienfeld is a system of sings invented by deaf children of hearing parents who receive no language input. Cases in which this happen tend to produce high functioning and normal individuals. But these situations where homesign is used as opposed to American Sign language still provided enough mental background for a person to learn a formal sign language later in life. These individuals present evidence for the need of some sort language in the infantile development phase of a child's life.
These cases of homesign or the extreme situation of Genie Wiley are a shocking example of language deprivation. Genie recovered as best she could from that terrible situation. This story is one that I could never forget and demonstrates the need for social linguistic connections. I hope there are never any situations in which a human is subjected to this kind of abuse.