Explaining and envisaging an ecological phenomenon

Two-way causal processes, in which a change in one factor affects a second factor which in turn affects the first, are an important feature of the natural and social world. Yet prior research (White, 1992, 1995) suggests that individuals only envisage one-way causal processes when they think of the natural world. The limiting factor may be the nature of their mental model of the situation. With the relatively complex tasks such as those used by White, individuals map be less likely to think through the consequences of a change. This paper reports four experiments which simplify the participants' task. They were asked to consider certain phenomena involving predator-prey relations. Experiment 1 required participants to account for specific variations in the size of a fox population over time. Experiments 2 and 3 required them, in various ways, to envisage how the size of a target population might change over time and to write down their accounts. Experiment 4 examined the effect of problem complexity. The results indicate that two-way causal accounts are an outcome of participants constructing small-scale mental models that they use to simulate the consequences of change.