I have a client who is pushing the use of very literal imagery for her website: waving hands for success, a finishing line for the end of a process, and so on. We're trying to make more use of indirect imagery, partly to support the brand but also to encourage deeper engagement. Is there any research available to show the relative merits of both approaches?
"One good experiment is worth a thousand expert opinions." — Bill Nye, the science guy.
I agree, test it against an alternative.
Use the better of the two.
Probably, nothing published will relate to your situation, specifically, unless it is too glib or vague to be of any practical use.
If you don't have enough time or money to test the concept in question, specifically, go with your client who is footing the bill and will get credit or lose credibility for the presentation in their name. It's their responsibility unless you claim to be a content expert.
It sounds like you need a good argument against the obvious design decision.
The book "A Smile in the Mind" states:
The best graphic design does more than capture attention and make the audience linger. It prolongs the encounter, compelling the reader not only to notice, but to remember. This book is about making graphics memorable by using witty thinking…
So if you want the users to remember the site, and stick around a bit more not being obvious/literal is one good way to achieve that. There are more in depth examples in the book but I'm away from my library at the moment and can't post anymore direct quotes. I recommend it as a read for anyone wishing to produce more witty designs.
I think this is what you are looking for: