Babies grow up in rich social environments in which one of their most important goal is learn to interact effectively with other people and lean on them to learn about the world. In order to relate effectively, the child must understand that other people have beliefs, desires and intentions, and these mental states serve to explain part of the behavior of others.
This ability to understand and attribute mental states to others and to oneself is known as Theory of Mind (TdM)
There are some consensuses within the scientific literature regarding the development of the TdM, for example, that three years old children know that different people can want and feel different things, and then, when they are four or five years old, understand that their beliefs may differ from those of the people (Wellman, 2015). It should be noted that the most of developmental psychologists have given prominence to the study of beliefs over the desires, almost always framed by structuralist models of development that relate or even justify the appearance of some capacity with the child's age (Kloo, Perner & Gritzer; 2010; Harrigan, Hacquard & Lidz, 2018; Woodward, 2003).
As mental states, desires fulfill a crucial role in social interaction. First, because many of the behaviors of human beings are motivated by desires, and so that to understand them implies in turn to understand part of the mind of the people; and second, because they are the first way babies have to explain the behavior of other people.
In this research study, changes in the understanding of the desires of preschool children between two and three years old were analyzed. Literature has taken for granted that children of these ages understand the desires, using methodologies that involve a single measurement to reach their conclusions, and protected by a structuralist position of development, where basically there is a description of milestones determined by age. In contrast to this tradition, this study is based on the theory of Nonlinear Dynamic Systems to address the understanding of desires with an emphasis on variability and change. Specifically, children ability to use simple desires to predict the emotions and behavior of others was evaluated, as well as assessing their ability to infer others desires based on preferences.
To do that, a microgenetic design was used, which involved several measurements of the variables in a short period of time, which allowed us to analyze the changes in the understanding of the desires at the time it occurred. For this, the minimum and maximum technique was used, a Nonlinear Dynamic Systems analysis technique that allows to calcule a change f trajectory or each child in relation to each variable:
After analyzing and classifying the trajectories of the participants in each of the three variables (use of desires for predict emotions and behaviors, and inference of desires) it was found that, unlike what most of the scientific literature suggests , children do not show high performance in these tasks throughout the evaluations. On the contrary, variability and irregularity were constant in many of the cases, which suggests that the understanding of desires does not necessarily follow a series of structured steps according to age. The results record several types of trajectories, marked by the variability and stability with performances of all types: low, medium, high and in few ideal cases. The investigation allowed to realize that with respect to the understanding of desires, children of similar ages show different trajectories of change, which supports the idea that development is not linear, and that it is necessary to approach the phenomenon from other methodological perspectives. In addition, the position of the majority of authors is discussed, with respect to the supposed ease of children of these ages to understand the desires.
Key words: Desires, Theory of Mind, Development, Variability, Dynamic Systems, Preschool children.