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Cichlids and stingrays can add and subtract ‘one’ in the number space from one to five

By March 31st 2022April 10th, 2022No Comments

Document type: Scientific article published in Scientific Reports

Authors: V. Schluessel, N. Kreuter, I. M. Gosemann, E. Schmidt


Preview: The numerical understanding of cichlids and stingrays was examined regarding addition and subtraction abilities within the number space of one to five. Experiments were conducted as two-alternative forced-choice experiments, using a delayed matching to sample technique. On each trial, fish had to perform either an addition or subtraction, based on the presentation of two-dimensional objects in two distinct colors, with the color signaling a particular arithmetic process. Six cichlids and four stingrays successfully completed training and recognized specific colors as symbols for addition and subtraction. Cichlids needed more sessions than stingrays to reach the learning criterion. Transfer tests showed that learning was independent of straightforward symbol memorization. Individuals did not just learn to pick the highest or lowest number presented based on the respective colour; instead, learning was specific to adding or subtracting 'one'. Although group results were significant for both species in all tests, individual results varied. Addition was learned more easily than subtraction by both species. While cichlids learned faster than stingrays, and more cichlids than stingrays learned the task, individual performance of stingrays exceeded that of cichlids. Previous studies have provided ample evidence that fish have numerical abilities on par with those of other vertebrate and invertebrate species tested, a result that is further supported by the findings of the current study.

Paper featured in articles in:
- Science, 31 March 2022: Fish can learn basic arithmetic
- Le Monde, 3 April 2022: Les poissons, maîtres du calcul

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From the Scientific Reports website