Lifestyle images should feature people from the product's core demographic, and eye contact should alternate across the sequence: the first lifestyle image makes eye contact toward the camera, the second looks away, then the third returns to eye contact. The claimed conversion benefit comes from the presenter's own testing/experience rather than an externally sourced study. See Main-Image Tactic Checklist and Secondary Image Set Testing for the images preceding this in the carousel.
Per 6 Steps to a Perfectly Optimized Amazon Listing, this pattern is presented as something 'tested across hundreds and hundreds and hundreds of listings' rather than a stylistic guess — i.e., an empirical CTR/conversion finding rather than an aesthetic preference.