Figure 1.

Predictions of the simplest form of the model of Bateson (1973, 1974). On both graphs, the vertical axis represents the chick’s preference during imprinting to a training object and the horizontal axis represents the difference d between the training object and any other object that is perceived as “slightly novel”; “slight novelty” corresponds to a level of novelty that is maximally attractive. d ranges between zero and W, the width of the stimulus continuum. Before imprinting starts, the model has no preference for any object: all are equally novel, equally attractive and d = W. After imprinting has started, preference for the training object increases linearly with time (t). d decreases linearly with time, as the chick becomes more familiar with the training object and is able to discriminate it better from a novel object. Point q represents the chick’s state as d changes with time. The attractiveness of “slight novelty” is given by i, which also increases linearly with time until discrimination is so good that d goes to zero and “slight novelty” ceases to exist. Thereafter, preference for familiar continues to increase unopposed to some limiting value. (A) State q₁ at time t₁. A preference for the now familiar training object has been acquired and the influence of “slight novelty,” given by i₁, is not yet strong enough to oppose the acquired preference for familiar; there is therefore a net preference for the training object relative to all others, including the maximally attractive “slightly novel” object. The position q₁ is defined by d₁ and i₁. (B) State q₂ at time t₂. Preference for the familiar training object over any other object has increased further, but the preference for “slight novelty” has increased sufficiently to give a net preference for “slight novelty” over the training object. At some further time, d will decrease to zero and preference for the familiar training object is thereafter unopposed. See Bateson (1973, 1974) for further details, including adjustments to account for real-world complications such as biases in the preferences of naïve chicks.