The present perfect

Citing

Citing with the present perfect simple is similar to the use of the present simple form, and can sometimes occur as an alternative to the present simple, but the present perfect is especially used to emphasise current relevance or continuing debate:

Berg and Hudson (ch. 6; Hudson 1989) have emphasised that modern factories need not have been large, yet the factories nonetheless were closely divided in their labour.

Schneirla (1966) has used the concept of ‘experience’ to mean all kinds of stimulative effects from the environment.

Recapitulating

The present perfect simple is used to summarise or recapitulate points or arguments in the discourse up to a particular moment, especially in concluding sections:

What is more, the qualitative analyses in this chapter have illustrated crucial aspects of the lexical characteristics of everyday spoken language, and although we have argued against over-generalisation from one-off analyses, it is true that one does not need much data to see the same features constantly recurring.

[literary stylistics seminar]
But of course we have talked about the shape of the poem and that’s where I want to go next. So if you have a look on the next sheet. We’ve talked about lexis, We’ve talked about morphology so far, and what we’re looking at now is graphology. That is the actual shape on the page.

Ongoing processes

The present perfect progressive is not typically used in concluding sections of academic texts, but may be used to refer to an ongoing process in the discourse up to a given point:

[discussing the way the playwright, Samuel Beckett, uses the space of the theatre stage]
This pure space, which has only extension but no location, is quite different from the theatrical spaces I’ve been discussing so far.

[embryology lecture]
And probably the surgical procedures that we’ve been talking about while thinking of ways of correcting before birth can have a major effect.