Laboratory animals are treated without the concern to avoid pain and anxiety to which they are entitled as sentient beings.
Since the aims of experiments upon animals in psychological research is to observe their behaviour, the experiments must necessarily be performed on conscious animals. Many experiments involve aversive procedures causing stress or pain. Deprivation of food and or water and the application of electric shocks are used routinely in learning tasks. Other fields of investigation include the effects of malnutrition, maternal deprivation, social isolation, physical restraint, sleep deprivation and situations especially designed to produce stress and anxiety. Only a minority of projects are concerned with enriched environment, pleasant stimuli and rewards. An interesting paradox which arises is that either an animal is not like humankind, in which there is no reason for performing the experiment, or else it is like humankind, in which case one ought not to do an experiment which one would not be prepared to perform on a human being.