Very little is known about the use children make of temporal concepts in their explanations of reality. The experiment presented here concerns the development of diachronic thinking in children, i.e. their ability to situate an object of knowledge along a temporal dimension and to conceive changes of this object over time. The experimental situation concerns forest disease and explores the child's ability to understand this phenomenon and to reconstruct the stages of its evolution. A total of 52 children aged from 8 to 11 years were asked questions about the past and future states of a diseased tree. The results show that important changes take place between 8 and 11 years in the conception of the evolution involved and reveal the components of a diachronic perspective. This perspective does not only consist of imagining and ordering steps in an evolutive process. It must also include the ability to establish a link between the steps by conceiving internal transformations that produce external changes. The changes constitute a continuous and gradual sequence, going from past to future. This diachronic perspective is not completely mastered before the age of 10-11 years. Before this, children have a punctual representation, imagine a small number of steps, a short time span and do not establish links between past and future.The genetic method in psychology, first adopted by Baldwin (1906), and later by Piaget (1924Piaget ( ,1970, is at the origin of developmental psychology today. This method has contributed a great deal to the study of cognition. It involves the application to the field of psychology of a perspective which is found in other sciences (e.g. physical chemistry, Prigogine & Stengers, 1981) and which is sometimes called evolutionist (Morss, 1990;Spencer, 1855) in reference to the model constituted by the theory of biological evolution. We prefer to use the more general term of diachronic perspective, which we define as the ability to situate an event on a temporal axis and to consider it as a stage in an evolutive process.The question we wish to address here concerns the foundations of this diachronic perspective and its contributions to the development of children's thinking. Such a question, in the field of developmental psychology has, of course epistemological implications, particularly as regards the problem of the contribution of the diachronic perspective to the knowledge of reality. These implications justify our interest in * Requests for reprints.

Classical work on the development of time concepts has focused on children's representation of time and reasoning involved in time measures. However, little is known about children's use of time concepts in their explanations of reality. The experiment presented here is concerned with the development of children's diachronic thinking, i.e. the ability to situate an object of knowledge (event, physical object, phenomenon, etc.) within a temporal dimension and to conceive of the changes of this object with time. The experimental situation explores children's understanding and reconstruction of the changes in their drawing abilities with age. A total of 70 children aged 6 to 12 years were asked to draw a human figure and then to produce as many drawings of a human figure as necessary to show how the drawings have changed over the years. They were then asked to sernate 12 human figure drawings produced by other children. The results indicate a progressive construction of diachronic thinking with age. Although children as young as 6 years are able to reason about changes in their drawing abilities, it is only at about 10 years that their reasoning reveals explicit use of diachrony.

Dream analysis can be a fruitful complementary technique in cognitivebehavioral therapy, providing it is based on a theoretical conception of dreaming and an interpretation method that are both compatible with the principles and methodology of CBT. The present paper first presents some aspects of a cognitive conception of dreaming explaining the occurrence and specificities of dream representations by their production processes. The next section describes an interpretation method that gives the patients the opportunity to find some sources and meanings of their dreams. Finally examples are given of the different ways in which the result of a dream interpretation contributed to therapy. Thanks to their condensed and often exaggerated treatment of a theme, dreams often facilitate becoming aware of cognitive distortions and schemas and help to proceed to cognitive restructuring. They also give to the therapists an opportunity to underline the patient's resources.

The diachronic approach consists of considering a phenomenon as a stage in an evolutive process. The authors postulate that this approach plays a role at the level of everyday thinking in the discovery of solutions to problems. The present experiment aims at studying the relationships between levels of the diachronic approach in children and their ability to imagine solutions to a conflict between children. Sixty children aged 8 to 12 years were presented first with tasks assessing their level of diachronic tendency (propensity to evoke past or future stages of a present situation), of dissociation of two temporal sequences (absence of covariation of a cause and its delayed effect) and of dynamic synthesis (ability to describe a set of pictures representing the successive steps of an event by a single noun phrase). During a second session, the participants were presented with a drawing representing two boys fighting in the playground and they were asked to explain the reasons for the fight. Participants then had to imagine several solutions to prevent the two boys fighting. Results showed a development in the ability to imagine solutions to a conflict and a significant correlation between the levels of this development and the levels of two aspects of the diachronic approach.

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