Researchers from Kyoto University's Primate Research Institute created a working memory task that involved displaying a series of numbers on the screen for a fraction of a second then covering them with boxes. The subjects (chimps and university students) were tasked to touch the white squares in the correct numerical order.
What they discovered was that the nine university students performed progressively worse as the time the numbers were visible decreased from 0.6 seconds to 0.21 seconds, as they had expected. The explanation is that humans cannot scan the screen fast enough to see and mentally record all of the numbers.
One of the two chimps in the study, Ai, demonstrated the same results. The other chimp, seven-year-old Ayumu, however, demonstrated no decreased ability as the time interval shrank. In other words, Ayumu actually performed better on this task than any of the students. The students' performance was on par with Ai, the older chimp.
Is it possible that the average, young university student has roughly the same cognitive abilities as a middle-aged chimp, and that younger chimps have better cognitive abilities than younger people? Sure, anything is possible. But it's not likely. Rather, the researchers believe that chimps in general (or at least Ayumu specifically) have much stronger eidetic memory (more commonly referred to as photographic memory) than the average human.
It should also be pointed out that the sample size of this study was limited to nine students and two chimpanzees. That's a pretty small sample for any real scientific study. However, this could open the door to new areas of cognitive research.