Unpredictability, Controllability, and Optimal Arousal/Stimulation Level as Applied to Zoo Environment Enrichment Theory and Practice

Success of zoo environmental enrichment, in spite of its widespread use and high significance for animals’ welfare, depends mainly upon keepers’ experience or the application of other zoos’ examples of daily practice. That’s why an algorithm based on some theoretical premises may be very useful for choosing the exact method of enrichment. We define the […]

Controllability in Environmental Enrichment for Captive Chimpanzees (Pan troglodytes)

This study considers the use of nonsocial environmental enrichment by captive chimpanzees at the Primate Foundation of Arizona. The goal was to determine whether a relationship existed between controllability of enrichment items by captive chimpanzees and frequency of use. The study measured controllability, the ability of nonhuman animals to alter aspects of their environment by […]

Stress revisited: A critical evaluation of the stress concept

With the steadily increasing number of publications in the field of stress research it has become evident that the conventional usage of the stress concept bears considerable problems. The use of the term ‘stress’ to conditions ranging from even the mildest challenging stimulation to severely aversive conditions, is in our view inappropriate. Review of the […]

The psychology of control: Effects of control over supplementary light on welfare of marmosets

It is often argued that increasing the amount of control that animals have over various aspects of their environment has a positive effect on their welfare, despite limited empirical evidence. We gave 12 pairs of common marmosets (Master pairs) control over supplementary light in their cages (additional to the regular room illumination). The light also […]

The effects of operant control over food and light on the behaviour of domestic hens

In intensive farming systems, the animals have little control over important elements in their environments. For instance, food of a pre-set type is delivered at set times, and the lighting schedule is controlled by the farmer. It has been suggested that low levels of environmental control over important events may reduce welfare by increasing passivity […]