Almost every scientific presentation ends with a picture of the lab members. Some presenters go further and show pictures of other collaborators, donors, etc. Presenters seem to think this indicates a generosity of spirit.
Such slides accomplish little. The pictures are only visible for a short time and the audience is not paying attention. Even if the lab member is in the audience, they remain anonymous. They may get a fleeting moment of pride, but nothing more.
Instead, the speaker should ask the contributing lab members to stand up. This will allow the audience to see who contributed and it may lead to audience members engaging them; a valuable experience for postdocs and graduate students.
And by the way, there is nothing more frustrating than hearing a PI conclude a talk by saying that a certain post-doc did most of the work. WHY THEN ISN'T THAT POSTDOC GIVING THE TALK? The PI's should teach that postdoc to develop and deliver the talk. The PI's role is to train the postdoc; not to hog all the glory while treating trainees like human pipettes!