Prematurely born children (PC) have academic difficulties related to poorer attention capabilities. Additionally, they often show excessive mobility, quoted as agitation. Some consider it could be related to poorer postural control and impaired perception of gravity vertical. But, this excessive mobility could also be an unconscious way for PC to improve their attention performance. The aim of this study is to evaluate the interdependence between postural and cognitive activities in school age PC versus term born children (TC). First, the performance of PC and TC at the Attention Network Test for Children will be analyzed with the use of a mobile versus a classic school chair. Secondly, participants will have to position a stick vertically to measure their perception of vertical gravity. Finally, the spontaneous postural activity of PC and TC (evaluated by the center of pressure displacement) will be studied during the execution of three different attention tasks at different levels of difficulty. Success rate and reaction time will be analyzed for all attention tasks. Moreover, center of pressure displacement calculation will allow evaluation of infants' spontaneous mobility, the precision of their postural control and the attention allocated to their posture.

Prematurely born children (PC) at school age have academic difficulties related to poorer attention capabilities. Posner (1990) described three distinct attention functions: Alert (to maintain a vigilance state), Orientation (to select the relevant information) and Inhibition (to resist distraction). Additionally, teachers and parents are often concerned because they move more than term born children; this excessive mobility being often quoted as agitation. Some consider it would be related to a poorer postural control potentially explained by a poorer perception of vertical gravity. Another explanation is that this mobility could be an unconscious way for PC to increase their arousal level to improve their attention performance. Therefore, the aim of this study is to evaluate the interdependence between postural and cognitive activities in school age PC and term born children (TC). First, the performance of PC and TC at the Attention Network Test for Children will be analyzed evaluating Alert and Inhibition, and its evolution when the infants will use a mobile school chair, compared to a classic school chair. Secondly, participants will perform a test of perception of vertical gravity in which they will have to position a stick vertically. Finally, the spontaneous postural activity of PC and TC (evaluated by the center of pressure displacement measured with a forced plate) will be studied during the execution of three different attention tasks: a vigilance task, a visual search task or an inhibition task at two different levels of difficulty. Success rate and reaction time will be analyzed for all attention tasks. Moreover, center of pressure displacement calculation will allow evaluation of infants' spontaneous mobility, the precision of their postural control and the attention allocated to their posture. Success rate and reaction time will be analyzed for all the attention tasks as well as the angle errors in degree between the stick orientation given by the children and the real vertical. Furthermore, the sway path, the surface area and the entropy of the displacement of CP will be computed to determine respectively the mobility, the precision of the postural control and the attention allocated to the posture of these children.

Inclusion Criteria:

• Children born before 37 weeks gestation or at term and routinely followed for their prematurity in the follow-up clinic of the Maternite Regionale Universitaire and healthy term born children recruited after information in different schools of Meurthe-et-Moselle
• Child whose holders of parental authority have received complete information on the organization of the research and have signed the consent

Exclusion Criteria:

• Severe hypotrophy at birth defined by a weight z-score below -2.
• Children with developmental, cognitive, visual or motor disability preventing the execution of the tests