This post's answer says that "to need" is imperfective because a perfective must be successfully completed, while many of the responses to this post seem to imply that a perfective doesn't need to complete it's objective but simply be a changed state. Can anyone clear this discrepancy up?
A perfective predicate regards the action as a whole, and only subsets of that whole are regarded as imperfective. 'To need' is no different than 'to eat' in terms of whether you can consider starting, progressing, interrupting or completing the action, or the entire (therefore started and stopped) action. In English, the only real imperfective predicates are those that use the active participle (verb+'ing').