Meaning of "pull figure" in the context of scientific papers

Solution 1:

I think the author means a figure that pulls the reader figuratively into the paper. Pull is used here in the meaning of

a force that attracts, compels, or influences

Large bodies of text aren't attractive and don't invite the reader to take more than a casual glance, especially when he/she is browsing through multiple papers. A picture (which, as the saying goes, says more than a thousand words) helps getting the reader's interest.

Solution 2:

This is related to pull-quote, which OED defines as

Typogr. and Journalism (orig. and chiefly U.S.) a brief and striking quotation taken from the main text of an article and used as a subheading or graphic feature, usually in a distinctive typeface; (also) a striking quotation used as a caption or graphic feature in an advertisement.

— Quotesgram, sample pull quote

The "pull" in pull-quote is that the extract used is pulled from the article and given prominence. Thus a pull-figure is an image or diagram which is pulled from the text of the main article into page 1 or 2.