It would mean we are effectively blind(er) to unfamiliar shapes, even though they are extremely simple, like a triangle or square are.
It could have something to do with their written language, for example, and shapes similar to triangles and squares in it appearing in a certain pattern that isn't the basic repeating XXOXXOXXO...
Or it could be music and rhythm is a big part of their culture, and XXOXX then follows with XXXO in a large number of their songs.
Those would have been things recognizable to me. Things I liked a lot.
Also, they would have put my mind somewhat at ease, I think.
I wonder how much of the inability to answer some questions is actually down to feeling slightly intimidated by the onslaught of questions, their sterile aura, not knowing the person presenting them, etc...
How much does the subconscious feeling of intimidation influence the ability to think?
Of course, it's always possible any individual study contained unknown and unaccounted biases. Funding in science is still relatively small, the number of people participating few and science itself is hard.