Personally, I have a very hard time believing that a study in unrealistic conditions, using people who have not learned to see, can accurately measure the limits possible for a person who has developed those skills.
Learning to see is a major part of becoming a skilled observer.
Expecting to know what is possible by studying a large group of people who have not learned to see is like trying to take a group of people who have never touched a basketball and having them try to shoot shots from half court to see if it is possible for a person to make shots from that distance. You don't measure what is possible by taking the average. You measure what is possible by studying the people who are exceptional in that endeaver. Have the same tests done with a large group of skilled observers under conditions that match what is found in nature, and see what the results are. Until then these tests results are questionable at best.