Birds such as crows, ravens, jays, and magpies may have subjective experiences.

Consciousness is still very difficult to understand within the animal kingdom. Commonly, consciousness is ascribed to humans and other primates, while others suggest it is a trait shared by mammals. It is even more difficult to understand if animals such as birds, insects, and fish have a conscious point of view. A new study out of the University of Tbingen in Germany published September 25th in Science suggests that birds such as crows may indeed have a subjective reality.

Consciousness can have many levels. The lowest level is sentience - or the ability to have a point of view. The next level is sapience - the ability to have a train of thought and to form opinions. Finally, there is the understanding of the self.

Even showing that birds and like animals have sentience would be revolutionary for our understanding of consciousness and the brain. For primates, consciousness is commonly associated with the cerebral cortex. Animals such as birds lack this portion of the brain.

The study, led by Professor Andreas Nieder, the chair of Animal Psychology at the University of Tbingen, examined crows, a subset of corvid birds (the class of birds that also includes ravens, magpies, and jays). They trained the birds to respond to a visual stimulus projected on a screen.

Sometimes the stimulus was clear and the birds indicated that they saw it. Other times, the stimulus was faint - on the verge of their perception. For these cases, even for the same faint intensity, sometimes the birds reported they saw the signal, and sometimes they didnt. This can not be explained by the workings of the eye, but must arise at higher processing levels of the brain that evaluate the sensory input, says Nieder.

Even more intriguing, sometimes the crows reported seeing something when nothing was actually there. The crows eyes were, in a sense, playing tricks on them, another indication of subjective reality.

Just like sometimes our eyes trick us in seeing things that aren't really there, crows were ... [+] similarly fooled, indicating they may have subjectivity.

During the experiment, the scientists also recorded the activity of nerve cells within the birds brains. If their experience was not subjective, the birds would have responded similarly to every faint stimulus. But this wasnt the case. The nerve cells were active only when the bird reported seeing the stimulus.

This activity was recorded in the nidopallium caudolaterale, or NCL. While birds do not have a cerebral cortex, their NCL routes sensory information to other parts of the body. Interestingly, this NCL evolved anatomically distinctly and independently over the course of evolution, and it is only found in birds, says Nieder. We think the NCL serves similar high-level functions in the bird brain as the prefrontal cortex in our primate brain, but there is no NCL in the mammalian brain, just as there is no prefrontal cortex in the bird brain.

These results are important for the understanding of consciousness in the animal kingdom. Crows and humans diverged on the evolutionary tree 320 million years ago. Either consciousness has been around that long, or it has evolved multiple times in the animal kingdom.

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Do Birds Have A Subjective Reality? A New Experiment Suggests So - Forbes