Animals are unlikely to analyze probabilities. Statistical inferences are only attributed to humans (and some apes). But there is also the Nestor notabilis, a bird better known in New Zealand as kea. This is a psittaciform species of the parrot family. He is able to understand the probabilities and decide based on them. It is the conclusion that emerges from the study entitled Kea show three signatures of domain-general statistical inference carried out by scientists from the University of Auckand. It is published this week in the specialized journal Nature Communications. The finding is the first to show the ability of statistical inference of any animal outside the group of great apes. And he introduces Kea, the parrot that uses statistics.
Experimenting with probabilities
They wanted to demonstrate the kea's ability to discriminate statistically between two options. Amalia Bastosy Alex Taylor, authors of the study, conducted a series of experiments. They were designed to verify that these birds had several criteria for statistical understanding based on previous studies conducted with primates and human babies. Thus, the researchers trained six keas. They were called Blofeld, Bruce, Loki, Neo, Plankton and Taz. They should associate the black color of a series of chips with a reward and the color orange with the absence of it. The authors varied the relative frequencies of the orange and black chips in two transparent jars. They offered the keas the choice between both jars, hiding the reward they would give the birds.
The authors discovered that kea preferred the jars in which a higher relative frequency of black chips was observed. Then the scientists placed a horizontal barrier that hid part of the jar. Thus, they changed the fraction of rewards tokens accessible above this barrier. The kea detected this physical restriction and re-selected the bottle that contained a higher proportion of gratifying chips. It was confirmed in a third experiment. Kea also preferred to select the files of one of the scientists who had previously demonstrated a "bias" to offer a larger fraction of gratifying tokens.
Like apes and humans
Prior to this experiment, a bird never demonstrated that aptitude. And no other animals, except the great apes. The kea, the parrot that uses statistics and decides based on it, is exceptional. Showing this type of higher order complex cognitive process in a bird opens a new door. It helps us understand the evolutionary history that has led great apes to understand probability and make decisions based on statistics.