Newly hatched domestic chicks were reared with five identical objects. On days 3 or 4, chicks underwent free-choice tests in which sets of three and two of the five original objects disappeared (either simultaneously or one by one), each behind one of two opaque identical screens. Chicks spontaneously inspected the screen occluding the larger set (experiment 1). Results were confirmed under conditions controlling for continuous variables (total surface area or contour length; experiment 2). In the third experiment, after the initial disappearance of the two sets (first event, FE), some of the objects were visibly transferred, one by one, from one screen to the other (second event, SE). Thus, computation of a series of subsequent additions or subtractions of elements that appeared and disappeared, one by one, was needed in order to perform the task successfully. Chicks spontaneously chose the screen, hiding the larger number of elements at the end of the SE, irrespective of the directional cues provided by the initial (FE) and final (SE) displacements. Results suggest impressive proto-arithmetic capacities in the young and relatively inexperienced chicks of this precocial species.

The present review aimed to analyze the scientific literature untill 2010 about the theories of Obsessive Compulsive Disorder in order to make clear how a biological and cognitive hypotheses might be integrated in a comprehensive point of view. In the analysis, at biological level were included neuroanatomic and neurophysiologic models and animal models; instead at cognitive level were included different theories of Salwoskies, Van den Hout, Mancini e Rachman. Biological, cognitive, and behavioral elements of the theories have to be clearly distinguished between specific and general conditions, as do critical past events and current trigger conditions. The theories compared were drawn from the neurobiological, cognitive, and behavioral literature that proposed empirical supported models. We conclude that there are substantive differences among the cognitive theories and between the biological theories reviewed. However, cognitive and biological theories appear to be compatible in principle. It is not clear whether substantive differences among theories are due to the existence of subtypes of OCD or due to the predominance of multifactorial cause. It is argued that current treatment methods imply particular theories, and that particular patterns of success and failure can be understood in relation to theory through the methods we have employed.

We investigate the relationship between inhibition and cognition in developmental age adding values for the understanding of EFs. The aim of this study was to examine the development of EFs by comparing children of different clinical populations: children with a Mild Intellectual Disability (MID) with atypical cognitive development and children with ADHD inattentive subtype with impaired inhibition development. Results obtained suggest that only a subgroup of MID has an inhibition deficit (not overlapping with ADHD). So, the data seemed to support the hypothesis that EFs, even when impaired, could follow different pathways of development, partially independent from intelligence. Moreover, our findings seemed to fit with the hypothesis that the diagnosis of intellectual disability include different neuropsychological phenotypes.