We use the zookeeper perspective as a practical tool. Not to disregard the complexity of culture, social structures and human psychology. But to temporarily strip away complexity and noise, to instead look at more basic structures first. This not only allows for greater clarity and a layered approach, without losing resolution as layers are added, but also allows for identifying basic structures which are in some instances much more effective intervention targets, and doing so as early as possible.
We call the first layer the tiger layer, the second the ape layer – the first and second together making up the complete zookeeper perspective – and the third the human layer.
The tiger layer involves considering biology, basic needs, the limitations of sensory input and our physical bodies – the simple, observable facts. When adding the ape layer, we also begin to consider emotion, cognition, heuristics and other adapted traits that are often considered ‘human’ – but which are largely unconscious processes. We are still only considering what can be observed and psychological factors that are common amongst not only among all humans, but also to a large degree other primates. We are still not relying on people’s own explanations for their behaviour, or – generally – individual preferences.
As we add the human layer, we begin to consider the relevance of individual differences, culture (e.g. cultural norms or corporate culture), ideology, religion and communication. Note that we only consider actual words, signs and language-based interventions at this level. Especially in the realm of physical designs or user interfaces, a physical space or virtual interface that intuitively drives the desired behaviour is generally much more effective – and elegant.
Dansk 
English (UK)