Present perfect or past simple when it is used with time adverb

Question

I'm not a native speaker so to understand the difference between past simple and present perfect is giving me a headache sometimes. I have learned, that when it is used in a sentence a time adverb describing a past event, I need to use present simple. But a few days ago I heard on the TV the following sentence:

It is better than what you have done previously.

But I would use:

It is better than what you did previously.

Because previously, yesterday, last week - all of these adverbs are set the story into the past. At least to me. Please, correct me if I'm wrong.

Answer 1

There is a small difference between using the simple present and present perfect in cases like those. The difference is that simple present may have more specificity than present perfect.

It is better than what you did previously.

This might seem to imply that "what you did" comprised a single event.

It is better than what you have done previously.

This can open the scope a little, and may refer to multiple events.

Note that the distinction here is small, and in actual usage either could be used to suggest a single event or multiple events.

Also be aware that a more specific time adverb (yesterday, last Monday) likewise narrows the scope.

Answer 2

Present Simple is used when something is set at a specific point in the past.

Present Perfect is about something that happened in the past—no matter when exactly—and is a fact now because of that.

E. g., I have read this book means that I have this experience of reading this book, it is now part of my intellectual "luggage". But whether I read it last week or 10 years ago is not essential.

Since "previously" is not about a specific time, this is why Present Perfect is used.

Answer 3

The time expression in a present perfect construction must not exclude the present. With previously there is an implicit reference to the present: what has happened previously happened before now.