Aspect (simple, perfect and progressive): What are the differences?

Solution 1:

Aspect does not refer to a difference in the things described. It refers entirely to how the speaker is choosing to refer to the events on that occasion: specifically, on the temporal relationship between the events and other events or points in time.

I was sleeping is focussing on the continuing state (in the past) of my being asleep. It can refer to precisely the same event as I slept or I have slept: the choice is in what we are saying about the event.

In English, for most verbs we use the so-called present continuous to talk about events which are happening at this moment, irrespective of how long they are continuing: She is wearing a jacket usually talks about the fact that at this moment she has a jacket, and says nothing about how long or how often she does so. For most verbs, we use the simple present only for habitual or universal claims: She wears a jacket talks about her habitual apparel. (It may or may not be true that she is wearing a jacket at this moment, but this does not affect whether She wears a jacket is true).

Verbs of perception and mental state usually do not behave in this way, and are used in the simple present (I see, I feel, I remember). They can be used in the continuous, but this is "marked" as linguists say, and expresses a specific meaning: focussing on the immediate currency of the state or perception. But again they do not express a different situation, just a different way of referring to it, with a different focus.

In the past, there are two more options - the perfect (I have seen) and the perfect continuous (I have been seeing). Again, the difference is in what we are focussing on, not in the events described. In I have cleaned my room, we are focussing on the present relevance of the activity, and on the action being completed. But we certainly can say I have been cleaning my room, about the same activity, but with a different focus.

One way to look at this is by considering what questions they might answer.

What have you done today? I have cleaned my room.

Where were you at 2:30 this afternoon? I was cleaning my room.

How did you spend the afternoon? I have been cleaning my room.