Why do people say "um" and "er" when hesitating in their speech?
I've always been a bit fascinated by speech patterns and how some people seem to litter their language with "filler" that doesn't carry any meaning. Most people, to some degree, litter their speech with non-word sounds ("um", "er" etc) and injection of filler words, such as "like" and "basically" -- the latter, for some reason, being very common in the techie crowd.
Once you start noticing this, it gets really, really annoying. Some people can hardly finish a whole sentence without the use of filler and some do it to such an excessive degree that most utterances are just a string of filler words and -sounds with only a minute amount of actual content thrown in.
Of course, I notice that I do this myself. Interestingly, the degree to which I do this seems to depend very much on whom I am speaking to and what the context is.