Monkeys Brains And Probabilistic Reasoning

A new study in monkeys has identified which part of the brain is likely responsible for probabilistic reasoning, work that may shed light on how humans weigh their options when making a decision.

Probabilistic reasoning is the process of reaching a decision based on incomplete information, where the choice may not result in a desired outcome. Scientists at the University of Washington in Seattle trained two rhesus macaque monkeys to choose which specific combinations of shapes on a computer monitor might result in a reward—in this case, juice.

The monkeys made their choice by looking at either a red or green light. The researchers ran thousands of trials a
day, making it virtually impossible for the monkeys to memorize patterns, says lead researcher Michael Shadlen.

During the experiment,