I'm not familiar with conducting a user experience test. Why is this so unbelievable? (Also, the rest of the story is kinda hilarious; there will definitely need to be some standards and process changes in academia.)
So if you assume that the UX tests were short (20-30 minutes) you're still talking ~15 total hours spent on UX testing, or two full work days. That would be a surprising amount of time.
As someone else said, it's conceivable that they ran very short studies on a large number of people in the context of having a party or a couple of small gatherings, but it does seem unlikely overall.
Thanks for explaining!
Is it possible that maybe he thrown a big party (or a series of parties) and asked the folks there to try his stuff? Not sure what is the length and depth of the usability test in question, but if it is a short questionnaire that might work? But I see where your suspicion is coming from.
Maybe that student was doing the same. Simply asking a lot of people. And other studends usually do not. I find it really hard to overcome my own shyness in this regard. And I wouldn't consider myself particularly shy. I assume a lot of people simply do not try asking enough people in order to get a decent amount of them to join.
Of course that guy might be simply cheating, but I just wanted to share the story.
Scan the signatures and reverse image search them. Or look one or two of the people up on facebook and ask them whether they did the study.
The consent forms are likely friends, so calling to ask questions about the experience should give you an idea of what to believe.
The outcome can be your decision. Meet with the student and tell them their degree is in jeopardy and use it as a teaching lesson, or prove to them that they can get away with believable lies as long as no one has the courage to catch them. Your colleagues should have some insights, as well.
This year one of my students claimed to have done a user experience test with 30+ people, all of which came in person to his house during a period of 4 days. This is extremely unlikely, not to say absurdly unrealistic. If he had done it via Zoom I might maybe believe, but in person? Sorry, but no. I asked him what did his parents think of it, and magically they were both travelling that specific week. Then I asked him to scan and send me the signed consent forms for each participant; he promptly said "ok, coming!" then about 8h later I got a bunch of signed scans. Not sure what to do anymore, I guess he'll have his thesis.