An experiment in Japan has shown that chimpanzees can outperform humans in short-term memory tests.

Japanese researchers pitted three adult chimps and three juvenile chimps against groups of college students in a test requiring increasingly good short-term memory.

The students failed first, followed by the adult chimps and then the juvenile chimps.
Professor Tetsuro Matsuzawa, from Kyoto University, who led the research, told The Press Association: "There are still many people, including many biologists, who believe that humans are superior to chimpanzees in all cognitive functions.

"No-one can imagine that young chimpanzees at the age of five have a better performance in a memory task than humans.

"Here we show for the first time that young chimpanzees have an extraordinary working memory capability for numerical recollection. It is better than that of human adults tested in the same apparatus and following the same procedure."

The humans and chimpanzees were taught to recognise symbols depicting 'one' to 'nine' and the order in which they were displayed.

Symbols were briefly displayed on a screen before being replaced by white boxes, which then had to be pressed in the right order.

The amount of time the numerals were displayed was reduced steadily. The young chimps required only a single glance to get the right answer for most of the test.

The research, published in Current Biology, reported that the chimps had an 80 per cent accuracy rate at about a fifth of a second, compared with 40 per cent for the human adults.

This so-called eidetic imagery, or photographic memory, is found in autistic humans.
Dr Matsuzawa speculated that it may have been an inherent ability in the chimpanzees' ancestors which humans subsequently lost as they developed speech.
The scientist also suggested that the older chimpanzees may have performed less well because their memory was occupied with other processes.