New users who are only using a little bit of regex will not know about the need for $ and ^. It will be one step up from complete string matching (without regex at all). They will therefore  be expecting just wildcards etc, and not to change anything else about the kinds of strings that match. I would therefore say that we should go with Ned's suggestion of assuming the beginning and ending matches as well. If users really want to match "sec" with "seconds", they can use "sec.*", as he mentioned. That the only way to match "*Martin Luther King*" with "Princess Martin Luther King of Wales" would be to do it on purpose.