Monkeys Can Order Items in a List

A new study backs up evidence of learning capabilities in monkeys. Rhesus macaque monkeys tested in the research successfully learnt the order of a string of items. Using logic, they were able to recall the order items. This ability to track order could be useful in the wild. Scientists believe the monkeys could use it to monitor social rankings. The study is documented in Science Advances.


Investigating Monkey Memorizing Abilities

During the research conducted by psychologists from the University of Columbia,
the macaque monkeys were shown an ordered list of seven images repeatedly. Images were then taken from the list in pairs and shown to the four monkeys. The monkeys had to select which of the two items was higher up in the list. They did this using logic and deductions about relative rankings.

An important factor in the study was the use of rewards, which consisted of additional gulps of water. The rewards were not given based on the rhesus monkeys’ successful selection. Sometimes, rewards were given for the right response, while other times rewards were given with an incorrect response. In this way, it was clear that the monkeys’ correct responses were not influenced by whether they would get a reward. This factor was unpredictable.

To rule out random chance, the four monkeys were subjected to 600 different ordering trials with the list of seven images, which included a zebra, a hot air balloon, and an ear of corn. The tests were divided into different sessions, with a different basis for giving rewards in each of them.

This study adds to evidence from other similar studies that have tested animals’ abilities to discern the order of items in a list. Other experiments done over the years worked with pigeons, apes, crows, and rats.

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