stimulus in this particular instance because it is only after the recognition of the egg's displacement that the fixed action pattern occurs.

The manipulation of the sign stimulus through a series of experiments can allow scientists to understand what specific component of the stimulus is responsible for the innate behavioral sequence. If the egg were to be picked up and taken away after it is displaced from the nest, the goose still exhibits the same head moving motion even though there is no egg present. This was put to the test by