Ants Can Anticipate the Following Quantity in an Arithmetic Sequence

Abstract

Workers of the ant Myrmica sabuleti have been previously shown to be able to add and subtract numbers of elements and to expect the time and location of the next food delivery. We wanted to know if they could anticipate the following quantity of elements present near their food when the number of these elements increases or decreases over time according to an arithmetic sequence. Two experiments were therefore carried out, one with an increasing sequence, the other with a decreasing sequence. Each experiment consisted of two steps, one for the ants to learn the numbers of elements successively present near their food, the other to test their choice when they were simultaneously in the presence of the numbers from a previously learned sequence and the following quantity. The ants anticipated the following quantity in each presented numerical sequence. This forethinking of the next quantity applies to numerosity, thus, to concrete items. This anticipatory behavior may be explained by associative learning and by the ants’ ability to memorize events and to estimate the elapsing time.

Ants Can Anticipatively and Correctly Increment the Last Quantity of a Learned Arithmetic Sequence

“…We intend to examine if, after having been trained to a continuous increasing or decreasing arithmetic numerosity sequence (1, 2, 3, 4 or 6, 5, 4, 3), the workers of the ant M. sabuleti could anticipate the exact following quantity in the sequence by testing them in front of 1, 2, 3, 4, 5, 6 or of 6, 5, 4, 3, 2, 1 elements. As the present work is the logical continuation of our previous one (Cammaerts & Cammaerts, 2021), the experimental design, protocol and statistical analysis were similar and are thus somewhat briefly described.…”

“…It had previously been shown (Cammaerts & Cammaerts, 2021) that the workers of the ant M. sabuleti trained to an increasing or a decreasing numerical sequence could expect that the following quantity would be larger or smaller. The present work needed to train the ants in the same way, and the obtained conditioning scores (first part of the experiments) were of a similar level, ca 80%.…”

“…They can acquire numerical symbolisms and use these symbols for adding and subtracting, including a symbol for zero. Moreover, we recently showed that, trained to an increasing (1, 2, 3, then 4) or a decreasing (5, 4, 3, then 2) sequence of number of elements, they can expect that the following quantity will be larger or smaller than the last perceived numerosity (Cammaerts & Cammaerts, 2021). In the latter work, the ants were finally tested in front of the numbers of the sequence and of the following one, i.e.…”

“…Further experimental work was therefore needed to find out whether ants can learn the exact incremental value and use it to anticipate the next quantity in the sequence. This work should be similar to the previous one (Cammaerts & Cammaerts, 2021), but by training the ants to either successively 1, 2, 3, and 4 elements or to 6, 5, 4, and 3 elements, and testing then finally in front of the numbers seen during training, the correct next number and the wrong still next number. They thus must be tested in front of 1, 2, 3, 4, 5, and 6 elements or 6, 5, 4, 3, 2, and 1 elements arranged in this sequential order.…”

“…They can thus present an acquired conditional behavior in a subsequent situation. They can also expect if the next quantity of a numerical sequence presented over time will be larger or smaller (Cammaerts & Cammaerts, 2021).…”