An ability to use tools on other tools – metatool task hereafter – proved to be an essential breakthrough in the evolutionary process of the hominins. Since this process requires several cognitive challenges to be completed, any individual able to complete it possesses a decent ability of physical cognition and hierarchically organized behavior. Taylor et al. (2007) experimented with a metatool task on New Caledonian crows. Their ability to solve it spontaneously implies they are capable of analogical reasoning.
For the experiment, a piece of meat was put in a horizontal hole 15 cm deep. Approximately two meters away, researchers placed two “toolboxes;” the frontal side of each toolbox consisted of vertical bars so that the birds could only insert their bills and not the whole head. In one toolbox, 4 cm away from the bars, so it is unreachable by the bill, they placed a stick 18 cm long. They put a stone the same distance away from the bars in the second toolbox. Lastly, a 5 cm long stick was placed in front of toolboxes. To complete the experiment challenge, the birds were first required to use the short stick to access the long one and then apply it to extract the meat from the hole. Before the experiment, each bird undertook several sets of familiarization trials. These trials were composed of using the long stick to access the meat, extracting the long stick from the toolbox to access the meat, and attempting to extract the meat with the short stick. Knowing about birds’ prior experience is essential to ensure they do not show any previously learned behavioral rules.
Seven crows were used during the experiment and safely released after its completion. The researchers decided to use New Caledonian crows instead of the other bird species due to their remarkable abilities in tool manufacturing (Montgomery, n.d.). The hypothesis was their cognitive abilities could further match the ones of primates that proved to be capable of metatool usage. Most great apes managed to properly use tools as metatools – five out of six gorillas and three out of four orangutans (Taylor et al., 2007). Consequently, the experiment was designed in a similar fashion; the stone in the second toolbox serves as a control tool to represent the possibility of the experiment’s completion by trial and error. To increase the experiment’s difficulty, researchers could swap the stone for an object resembling a stick more closely – a rope.
Successful completion of the experiment implied the presence of analogical reasoning in crows’ behavior. In other words, the crows must use their previous experience on a new problem, which is different in some aspects but is structurally similar nonetheless. During the experiment, six out of seven crows used the short stick to reach the long one; more importantly, they attempted it on their first try (Taylor et al., 2007). These results have two indicators of analogical reasoning: successful experiment completion and an attempt to reach the long stick on a first try. The former implies the crows’ ability to solve metatool tasks; the latter signalizes spontaneity in their solution, which requires a more complex cognition than simple learning. Researchers swapped the sticks and repeated the experiment to prove that crows understood the causal relationship between the regular tool use and the given task. As a result, each crow probed the toolbox to access the short stick but did not use it afterward. Furthermore, they corrected their mistakes quickly on the next try, proving the experimenters’ suggestion.
The crows showcased the signs of analogical reasoning during the experiment. Firstly, the previous absence of metatool tasks in their experience rejects the suggestion of previously learned behavioral rule usage. Secondly, little attention to the stone from the second toolbox denies the suggestion of learning by trial and error. Lastly, a swift rectification of habitual behavior indicates a casual understanding of the means and the final goal. Ultimately, by showing similarly successful results in metatool task solving compared to the great apes, crows proved their analogical reasoning, which might explain their tool-manufacturing propensities.
References
Montgomery, S. (n.d.). Crow. Encyclopædia Britannica. Web.
Taylor, A. H., Hunt, G. R., Holzhaider, J. C., & Gray, R. D. (2007). Spontaneous metatool use by New Caledonian crows. Current Biology, 17(17), 1504-1507. Web.