By Bruce Bower
Monkeys can keep strings of information in order by using a simple kind of logical thought.
Rhesus macaque monkeys learned the order of items in a list with repeated exposure to pairs of items plucked from the list, say psychologist Greg Jensen of Columbia University and colleagues. The animals drew basic logical conclusions about pairs of listed items, akin to assuming that if A comes before B and B comes before C, then A comes before C, the scientists conclude July 30 in Science Advances.
Importantly, the size of rewards given to monkeys for correctly identifying the higher-ranking item in a pair didn’t always provide reliable guidance to the animals about the item’s ranking on the list, Jensen’s group says.
Previous studies have suggested that a variety of animals, including monkeys, apes, pigeons, rats and crows, can discern the order of a list of items (SN: 7/5/08, p. 13). But debate persists about whether nonhuman creatures can actually develop an internal knowledge about what items come before others in a list.