Comment by RossBencina a day ago
A search for "Gloria Mark 23 minutes" is interesting reading.
At this point I would suggest going to the source, establish contact with Gloria Mark or a relevant student or co-author and ask whether Dr Mark can confirm that it is an accurate quote, and if so, whether it is a published result. One approach might be to develop the enquiry through a potentially sympathetic third person such as Cal Newport.
For a lot of us that would definitely count as a source. They seem to be credible, they seem to be quoted in a credible media outlet, they seem like an experts on the topic, they seem like they're talking about a real and specific piece of research. So I think that would count for a lot of us. But for purposes of this particular article they're looking for a printed primary source of the research itself rather than a quote about it.
> When people did resume work on the same day, it took an average length of time of 25 min. 26 sec (sd=54 min. 48 sec.).
From the Gloria Mark paper: https://ics.uci.edu/~gmark/CHI2005.pdf
That's the paper source. And the researcher when interviewed verbally gave a slightly different number in the same ballpark of 23 minutes and 15 seconds instead of 25 minutes and 26 seconds.
This is the source: https://news.gallup.com/businessjournal/23146/too-many-inter...
Gloria Mark said it in an interview in 2006.