The next sentence says "The test subject is able to flip between the two distortions, and has the original image available on the side for comparison at all times.", which indicates that the subjects weren't shown only the distortions.
Of course you're right, but it doesn't mean anything.
It's like saying that you should buy people lottery tickets instead of healthcare.
I once heard that the US citizens most vehemently against raising taxes for the rich were the homeless, because they didn't want THEIR taxes raised once THEY became rich.
The US causes terrorism by steam rolling third world countries, but more or less has to do it now since these third world countries already hate the US enough to require this kind of policing.
If you encode each packet in a QUIC stream with it's own stream ID, and close QUIC streams after a timeout, you can use QUIC for unreliable unordered transports as well.