No abstract

The ability to form equivalent relations between sign and referent—symbolization—is one of the important cognitive components of language. Equivalent relations have the properties of symmetry (if A→B then B→A), reflexivity (A→A, B→B), and transitivity (if A→B and B→C, then A→C). The current study evaluates whether reflexivity can be spontaneously revealed in hooded crows (Corvus cornix) without training after the formation of the symmetry relation. These birds were previously taught an arbitrary matching-to-sample task with the letters “S” and “V” as samples, and sets of images (same-sized and different-sized figures) as comparisons. Positive results in the transfer tests showed that the crows associated letters with the concepts of sameness/difference. After that, they successfully passed the symmetry test, in which samples and comparisons were switched around. In the present experiment we found out that the crows passed the reflexivity test (A→A, B→B) without identity training. We hypothesize that if the subject associates the sample not with certain stimuli but rather with concepts, it facilitates the formation of equivalence relations between them.

Body-awareness is one of the manifestations of self-awareness, expressed in the ability of people and animals to represent their own body physical properties. Relatively little work has been devoted to this phenomenon in comparison with the studies of the ability of self-recognition in the mirror, and most studies have been conducted on mammals and human infants. Crows are known to be “clever” birds, so we investigated whether hooded crows (Corvus cornix) may be aware of their own body size. We set up an experimental design in which the crows had to pass through one of three openings to reach the bait. In the first experiment, we studied whether crows prefer a larger hole if all the three are suitable for passage, and what other predictors influence their choice. In the second experiment, we assessed the ability of the crows to select a single passable hole out of three on the first attempt, even though the area of the former was smaller than that of the other two. The results of the first experiment suggest that when choosing among three passable holes, crows prefer those holes that require less effort from them, e.g., they do not need to crouch or make other additional movements. In the second experiment, three of the five crows reliably more often chose a single passable hole on the first try, despite its smaller size. We believe that these results suggest that hooded crows may be aware of their own body size.

Московский государственный университет им. М.В. Ломоносова, Москва Исследование процесса символизации (т.е. установления отношений эквивалентности между знаком и обозначаемым -референтом) у животных вносит вклад в понимание биологических предпосылок возникновения языка человека. Для изучения факторов, влияющих на формирование эквивалентных отношений между знаком и референтом, серых ворон без предшествующего экспериментального опыта обучали использовать знаки для обозначения понятий «сходство» и «различие». Одну из четырех птиц удалось обучить по знаку "S" выбирать изображение одинаковых по размеру, а по знаку "V" -разных по размеру фигур (A→B). Тесты на перенос правила выбора на новые стимулы (сходные и различные либо по знакомому признаку -размеру фигур, либо по новому признаку -их форме) показали, что ворона связала знаки не с конкретными стимулами, а с понятиями «сходство» и «отличие». Далее эта птица справилась с тестом на понимание симметричности отношений между знаком и обозначаемым (B→A), с которым животные обычно не справляются, а также с тестом на понимание рефлексивности (A→A, B→B). Таким образом, впервые получены данные, свидетельствующие о том, что понимание симметричности и рефлексивности отношений между знаками и их референтами может возникнуть спонтанно. Полученные данные указывают на ключевую роль типа референта для формирования истинно эквивалентных отношений, а также на важность понимания симметричности в появлении другого свойства эквивалентных отношений -рефлексивности.

Human language based on symbolization or sign-referent equivalence relations. The paper focuses on methods of studying the process of developing of sign-referent equivalence. Subject is trained in Matching-To-Sample task: for example, reinforcing of stimulus B if the sample was A, and stimulus D if the sample was C. Following test allows to reveal if new relations (for example, symmetry, if subject chooses stimulus A if the sample was B) appeared spontaneously. Human subjects usually pass this test successfully. This result may be explained by repeated demonstration of sign-referent symmetry during language learning and using. Our paper is dedicated to methods features which can be used to study sign-reference developing in human and animals. We discuss factors that leads to appearance of this crucial property of stimulus equivalence.