Pigeons are quick in multitasking
Pigeons are generally not considered very clever. For example, "you stupid dove" is a common saying. But a study now shows that pigeons can quickly switch between two tasks like humans. In some situations, the pigeons are even faster than humans, as research has shown. The biopsychologists suspect the higher neuron density in the pigeon's brain as the cause of the slight advantages of birds in multitasking.
The distance between nerve cells in pigeons is half that in humans. If groups of nerve cells have to exchange information very quickly, pigeons are faster (© Onur Güntükürn)
In the journal "Current Biology" Dr. Sara Letzner and Prof. Dr. H. c. Onur Güntürkun from the Ruhr University Bochum together with Prof. Christian Beste from the University Hospital Carl Gustav Carus at the Technical University Dresden.
"For a long time it was believed that the six-layered cerebral cortex of mammals is the anatomical origin of cognitive abilities," says Sara Letzner. Birds do not have such a structure. “So the structure of the mammalian cortex cannot be the prerequisite for complex cognitive functions such as multitasking,” continues Letzner.
Packed six times closer
The brain mantle of birds, the pallium, does not have any layers comparable to the human cortex. For this, the neurons are packed more densely than in the human cerebral cortex: for example, per cubic millimeter of brain pigeons have six times more nerve cells than humans. As a result, the average distance between two neurons in pigeons is only half that in humans. Since the signals from nerve cells are transmitted equally quickly in birds and mammals, the researchers had assumed that information can be processed faster in the bird brain than in mammals.
They tested this hypothesis with a multitasking task that 15 people and 12 pigeons completed. The human and animal test subjects had to stop an action in progress and switch to an alternative action as quickly as possible. The change to the alternative action took place either simultaneously with the stopping of the first action or with a short delay of 300 milliseconds.
What makes pigeons faster
In the first case, real multitasking takes place, so two processes run in parallel in the brain: namely, stopping the first action and switching to an alternative action. Both pigeons and humans are slower to the same extent due to the double load.
In the second case - changing to an alternative action after a delay - the processes in the brain change: the two processes, i.e. stopping the first action and switching to the second action, alternate like a ping-pong game. To do this, the groups of nerve cells that control the two processes must constantly send signals back and forth. The researchers suspected that pigeons should have an advantage because of the greater density of nerve cells. In fact, they were 250 milliseconds faster than humans.
"In cognitive neuroscience, it has long been a mystery how birds with such small brains and without a cortex can be so smart that some of them, such as crows and parrots, can cognitively take on chimpanzees," says Letzner. The results of the current study give a partial answer: Especially because of the small but tightly packed brain with nerve cells, birds reduce the processing times for tasks that require a fast interaction between groups of neurons.
The study was financially supported by the German Research Foundation as part of the project "Development of a neural causal model for mechanisms of target activation processes in multitasking" (GU 227 / 20-1, BE4045 / 20-1) as well as by SFB 874 and SFB 940 , Project B8.
Sara Letzner, Onur Güntürkunst, Christian Beste: How birds outperform humans in multi-component behavior, in: Current Biology, 2017, DOI: 10.1016 / j.cub.2017.07.056