Most research on numerical development in children is behavioural, focusing on accuracy and response time in different problem formats. However, Temple and Posner (1998) used ERPs and the numerical distance task with 5-year-olds to show that the development of numerical representations is difficult to disentangle from the development of the executive components of response organization and execution. Here we use the numerical Stroop paradigm (NSP) and ERPs to study possible executive interference in numerical processing tasks in 6–8-year-old children. In the NSP, the numerical magnitude of the digits is task-relevant and the physical size of the digits is task-irrelevant. We show that younger children are highly susceptible to interference from irrelevant physical information such as digit size, but that access to the numerical representation is almost as fast in young children as in adults. We argue that the developmental trajectories for executive function and numerical processing may act together to determine numerical development in young children.
According to the most widely accepted theory of numerical cognition (Dehaene, 1997), the human brain represents numerical magnitudes in an analog manner. This analog magnitude representation is akin to the way we represent physical magnitudes, for instance size, luminance or line length. Several investigators have studied the putative electrophysiological markers of the analog magnitude representation in adults (Dehaene, 1996, Libertus et al., 2007, Pinel et al., 2001, Szucs and Csepe, 2004a, Szucs and Csepe, 2004b, Szucs and Csepe, 2005a and Szucs and Csepe, 2005b) and in adolescents/children (Soltész et al., 2007, Soltész et al., 2011, Szucs et al., 2007 and Temple and Posner, 1998). Some of these studies have demonstrated that the impact of developing executive functions has to be taken into account if we want to understand behavioural developmental effects in number cognition (Szucs et al., 2009, Szucs et al., 2007 and Temple and Posner, 1998). As demonstrated by Temple and Posner (1998), electro-encephalography (EEG) provides an optimal means to disentangle numerical and executive processes because of its high temporal resolution. In the current study, our objective was to disentangle executive and numerical processes in the developmental trajectory of numerical processing during the initial stages of primary school education.
