International Journal of Comparative Psychology

This study compared three captive orangutans and a group of 5-10 year-old children in their ability to use stick tools to solve a series of mazes in a puzzle box, including three puzzles that required semantic prospection. The puzzle box had seven levels and moveable plastic inserts that created three easy, three intermediate, and three difficult maze configurations. Three wood and three plastic stick tools were presented with each maze. All 26 children immediately solved the easy and intermediate mazes. Seventy-nine percent of the children solved the difficult mazes on their first attempt, and nearly all the children solved the difficult mazes on the second attempt, which suggested a majority of children engaged in effective planning. Girls took significantly longer to solve the intermediate mazes while boys took significantly longer to solve the difficult mazes. Two of three orangutans also successfully avoided the dead ends in the difficult mazes and consistently used stick tools to move peanuts to the goal slots, and took longer to solve the intermediate or difficult mazes. Both the children and orangutans preferred to use plastic tools, although both tool types were functional. These results suggest many similarities between orangutans and children’s abilities to use tools in a puzzle box task that requires planning to avoid dead ends.