Present Perfect Continuous?

[Levon]

Hi there.

There's a such a sentence:
I often get a headache when I've been working on the computer.

I wonder why Present Perfect Continuous Tense is used here?

I often get a headache when I work on the computer.
Doesn't this sentence (Present Simple Tense) have the same meaning?
If not, please, tell me the difference between them.

Thank you!

[Cerberus™]

In this context, I'd say they mean almost the same. Do you understand the general difference between continuous and non continuous? And the difference between present perfect and past simple?

[Levon]

Yes, I understand the differences between them.

I try to understand other thing, why did they use perfect continuous?
Maybe because it's just an example from a book...
I think no one will make such a sentence with perfect continuous when the simple tense has the same meaning.
anyway thanks

[Cerberus™]

The first sentence does sound quite natural. The present perfect lays a bit more more emphasis on the fact that a period of working precedes the headache: you are working for some time, up until the moment you get the headache. The same actually happens in the second sentence, but it is implied from context, not indicated by the tense used. In the second sentence, the headache most likely doesn't start at the exact same moment you begin working - which would be possible based on tense alone.

[Levon]

Thanks. Now I see...
Then what if we change 'a headache' to 'headaches'?

I think here we'd better say "I often get headaches when I work on computer"
or maybe "... when I've worked on computer". ???
Is the perfect continuous right here?

[Cerberus™]

I don't think it changes much, except that the plural of headache seems to be a bit uncalled for. You either get a headache or not, but you don't get several headaches. That is, not in normal situations. If you added the plural with a view to giving each instance of "often" its own headache, I don't think that's necessary. I'm not entirely sober but I'll try to think up why tomorrow.

[Levon]

Well. I found out something...
In order to describe repeated single events we can use both singular and plural nouns:
When there are no details given, plural nouns are more natural. "I often get headaches".
But when details of the time or situation are given, nouns are singular. "I often get a headache when I work on the computer".
So my examples with plural 'headaches' are not correct...
Concerning the tenses used, I understood that there is no deferrance in meanings, it's only for putting more emphasis.
And I think that present simple is grammatically more correct..

[Cerberus™]

I think you're right, that there is some sort of preference to the plural in short sentences, though I do not believe it is very strong. I do not see why the present perfect should be any less correct.

[Levon]

I think we should use the perfect continuous for more detailed cases, for example if there were mentioned 'for a long time' or 'all day long' etc.
But there aren't such details and 'I get a headache almost every time I work on the computer', that's why it seems to me that present simple fits here more than perfect tense. Though I agree that perfect tense puts emphasis on it.