How do adult humans compare with New Caledonian crows in tool selectivity?

We examined humans’ tool selections on stick-and-tube tasks similar to those used to study crows’ and other avian species’ physical cognition. In Experiment 1, the participants selected a stick from a set of 10 to retrieve a candy placed in a horizontal tube. Although the stick that was selected depended on the distance to the candy, the participants generally did not select a stick whose length was the same as the candy’s distance from the open end of the tube nor did they select the longest stick in the set—two strategies that have been reported in crows. In Experiments 2 and 3, we used variations of the stick-and-tube task to determine what factors in addition to the candy’s distance influenced the participants’ selections. The results showed that tool selection depended on the stimulus context (i.e., the number and lengths of the alternative tools).