His model for how certain behavioural reactions are provoked was based on work by Konrad Lorenz. Lorenz postulated that for each instinctive act there is a specific energy which builds up in a reservoir in the brain. In this model, Lorenz envisioned a reservoir with a spring valve at its base that an appropriate stimulus could act on, much like a weight on a scale pan pulling against a spring and releasing the reservoir of energy, an action which would lead an animal to express the desired behaviour.