The perception of geometric regularity in shapes, a variant of elementary geometry, has long been considered an ability that only human beings had. And it is no wonder, since from quite early stages of development and across multiple cultures, our species has demonstrated a natural understanding of spatial rules. But this has changed in a species similar to crows.
A radical change. Although this innate quality of humans was quite well established, science has now shown that the crows too They have geometric understanding. A cognitive milestone that rethinks what we thought we knew about animal intelligence and the evolution of pure mathematics.
A myth. The scientific bases showed a notable gap between human abilities and those of the rest of the animal kingdom with regard to euclidean geometry. Previous research had already seen that primates lacked the ability to recognize geometric regularity in tests of visual perception of shapes, something fundamental, since they may be the first that come to mind when thinking about this property.
And this was crucial to determining that humans have an innate ability to process geometric regularity, since the recurring inability to species like baboons After intensive training he laid these foundations. However, the researchers decided to explore these abilities in birds known for their impressive cognitive and arithmetic skills.
Touch screens. To test birds’ spatial intuition, scientists from the University of Tübingen They designed an experiment based on the detection of visual anomalies. In this case, two 10- and 11-year-old male crows were trained using touch screens located inside conditioning chambers.
Here the birds could observe an array that displayed six simultaneous shapes on the screen and the task was to detect an “intruder”, that is, to peck at the shape that differed in its visual parameters with respect to the other five base stimuli.
The tests. For the final test, five reference quadrilaterals were used, ordered by their level of regularity: the square, the isosceles trapezoid, the rhombus, the right hinge, and a completely irregular shape. From here on, the “intrusive” figures were artificially generated moving the lower right vertex of the original figure at a fixed distance equivalent to 75% of the average distance between the vertices.
Results. The most impressive thing seen was the immediacy of understanding the problem, as the crows were able to apply the concept of detecting the intruder immediately upon being exposed to the new sets of quadrilaterals.
Both subjects dramatically exceeded the 16.7% chance level during their first trials, demonstrating that they understood the task without hesitating or mindlessly pecking. Furthermore, during the first 60 trials, the first crow achieved 48.3% success and the second crow 56.7%.
The most impressive thing. The most revealing data from these tests was precisely that the birds showed significantly better performance with shapes that presented properties of pure Euclidean geometry, such as right angles, parallel lines or symmetry.
It is crucial here to highlight that this performance advantage did not require extensive prior training, but rather the regularity effect was present from the very beginning of the testing phase.
Because? Faced with the logical question of why crows achieved what other primates failed, the authors of the study recognize certain important methodological differences compared to classic experiments with baboons. In this case, they point out that the crows were subjected to a strict progress criterion during training, needing to maintain 75% correctness over five consecutive sessions. In contrast, baboons only needed to reach a criterion of 80% correct responses only once, without the need for consecutive sessions.
And although this difference may make a direct and exact comparison between the species difficult, the main finding is incontestable: crows recognize geometric regularity.
Images | Tyler Quiring
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