Although emotions in animals were demonstrated rather early by
the pioneering work of Charles Darwin (1872/1998), their study has
not become an essential topic in science until about the 70ties of the
last century (Panksepp, 1998). Nowadays, however, many experts
agree on the assertion that not only humans, but also other higherorder
animals, especially mammals, are endowed with basic emotional
mechanisms, since they show species-specificemotional
responses in behaviour (like freezing, avoidance or approach), facial
expressions, and various physiological reactions, which are similar or
homologous to those of humans in comparable situations. Also, some
researchers assume that animals, for example rats, may have basic and
emotion-specific feeling states, that is, the feature, which humans
often consider as most characteristic for their subjective emotional
experiences (Panksepp, 1998). Similar to man, the study of animal