The ability of rhesus macaques to perform elementary mathematical actions

Rhesus macaques were presented as an example with multitudes in the range from 1–2 to 5–6 “dots,” 10 mm in diameter, on the monitor screen. By consecutive discrete pressing the key with “+” symbol, the monkeys formed on the “field of counting” a randomized multitude equal to that presented as an example. O. Koehler’s hypothesis of connection between counting and thinking and the proximity of the consecutive effector form of counting to discrete nature of human language is discussed.