There is a video at the end that gives a synopsis of all of this.
We have generally believed that animals are not capable of very complex thought, even though many species use tools and engage in other complex behaviors.
Even a bird brain appears to be capable of understanding things that are not visible may be affecting their environment.
This study looks at whether New Caledonian crows, that were caught just for this experiment, are capable of attributing actions to a hidden cause, when they see that possible cause come and go.
When discussing science, some humans do not behave as if we have any greater understanding of causality than these crows. Some do not seem to be able to understand the difference between David Hume’s work and solipsism.
Dig deep. New Caledonian crows are known to use tools; they can also reason out the presence of hidden mechanisms.
Credit: Mick Sibley
During the HCA (Hidden Cause Agent) trials, there is one human in the room to discourage the crows from entering and taking the food before the start of the trial.Another human enters, goes behind the blind, moves the stick, comes out from behind the blind, then both people leave. Once the people have left, the crow has no reason not to go get the food.
During the UCA (Unknown Cause Agent) trials, there is still one human in the room to discourage the crows from taking the food, but the stick is seen to move without the entrance or exit of any other human. This human is nowhere near the stick. After the stick stops moving the human leaves, so that the crow may feel somewhat safe about entering and getting the food.
The crows showed significantly different behaviors depending on whether there appeared to be an identifiable cause of the movement of the stick.
HCA – If there was a cause, and the cause had left, the crows paid less attention to the place where the stick came from.
Don’t worry about the stick. It’s just a human doing weird human things – and she left.
UCA – Without a cause, there appeared to be greater anxiety about the place the stick had projected from.
Watch out for that arbitrarily moving stick. I sure hope the stick does not poke me while I am trying to get the food. I don’t want to be food for something else.
Fig. 1. Inspection rate across conditions. Final habituation trial before testing is indicated by 20cm hab. (Upper Left) Diagram of the HCA condi-tion. (Upper Right) Diagram of the UCA condition. In the HCA condition, one human walked into the hide and one stood in the corner of the room. A wooden stick was then probed from the hide. The agent then exited the hide. Both humans then left the room. In the UCA condition, one human entered the cage and stood in the corner. The tool was then probed through the hole. The human then left.
Some of the UCA crows even flew away before they could get the food, but none of the HCA crows left without food.
Fig. 2. Average probes abandoned across conditions. Final habituation trial before testing is indicated by 20cm hab. An abandoned probe was defined as a crow inserting the tool into the hole and then leaving the testing area without extracting the food.
Here is an interview with Alex Taylor, one of the authors of the paper giving a synopsis of the study.
The UCA crow making 12 inspections is outside of the standard deviations for all three of the Unknown Cause Agent trials. Similarly, the HCA crow obtaining food after only 2 inspections is outside of the standard deviations for all three of the Hidden Cause Agent trials. This is a video, so some of the more extreme examples can help to make the point more clearly, even if not they are not representative of average behavior of either circumstance. Some of the Unknown Cause Agent trials resulted in the crow flying away before even obtaining the food, while none of the Hidden Cause Agent trials resulted in the crow leaving without food.
My first impression was of teaching intubation to people unfamiliar with intubation. Some will continually interrupt themselves, while others are more focused. Humans tend to move their heads much more slowly, but we do seem to allow ourselves to be distracted by the irrelevant. We are probably not going to be poked by a stick while attempting intubation, but we seem to be worried about the way we are perceived, which results in worse skill at intubation.
 New Caledonian crows reason about hidden causal agents.
Taylor AH, Miller R, Gray RD.
Proc Natl Acad Sci U S A. 2012 Sep 17. [Epub ahead of print]
PMID: 22988112 [PubMed – as supplied by publisher]
Taylor AH, Miller R, Gray RD. (2012). New Caledonian crows reason about hidden causal agents PNAS DOI: 10.1073/pnas.1208724109