Famous Russian scientist I.P. Pavlov considered the language, “second signal system”, to be a human being’s exclusive privilege. Modern researchers think that animals also have more or less developed language skills. For many years scientists from different countries have been working with apes, mainly chimpanzees, in order to teach them various types of language. Results of numerous research showed that apes are able to learn that objects and ideas can be encoded with certain symbols – gestures, words or figures. And the ability to symbolize is the main requirement for language formation.

The scientists from Saint Petersburg Pavlov Physiology Institute have worked with not apes, but rhesus monkeys. They’ve decided to estimate monkeys’ ability to symbolize by means of dialogue with the computer. Animals were sitting in front of a computer monitor, separated with a transparent screen. Various figures were displayed at t the monitor, and keys for pressing were also available.

During the preparatory training the monkeys were taught to follow figures, moving on the screen, with their hand. Then first test followed. The sample figure appeared in the upper part of the screen, and two more figures – in the lower part. One of these two figures was the same as the sample one, and another was different. The monkey should have picked the sample pair by pressing the keys. If the try was successful, the monkey received nuts or cookies. After the monkeys' answers were 80% correct, the researchers shifted to another pair. Every new pair was solved quicker than previous one, - the monkeys have learned “choose-the-same-as-the-sample” rule and used it.

The next task for the monkeys was squares and triangles, the “Q” key responded for the square and “T” key – for the triangle. When the monkey leaned the keys, the scientists showed it figures of different size – big ones were marked as “E”, and small ones – as “B”. So, when the monkey saw little triangle, it should have pressed “TB”, and “QE” is case of big square. The second part of the experiment was held after half a year break. More figures appeared – ellipse, star, circle and rhomb.

It required numerous tries for all three monkeys to learn to link figures and their size with proper symbols – letters. It appears interesting that one monkey described figure size with absolutely antagonistic keys. The scientists agreed not to retrain the animal and accepted its’ own “language”. Nevertheless, all monkeys have learned to use eight symbols to describe figure’s size and geometric shape. This points to the fact that monkeys have the ability to symbolize – to mark figures with letter symbols. Moreover, they were able to learn the general concept of “big-small” and to understand that it could be encoded by symbols.

The experiments with teaching language to the apes have knocked the bottom out of the theory about an impassable gulf between human mentality and ape mentality. The Russian scientists showed that some language skills elements are teachable not only to the apes, but also to other monkeys.