Efficiency of visual information processing in children at-risk for dyslexia: Habituation of single-trial ERPs Anne G.F.M. Regtvoort * , Theo H. van Leeuwen, Reinoud D. Stoel, Aryan van der Leij Faculty of Behavioural and Social Sciences, Department of Educational Sciences, University of Amsterdam, P.O. Box 94208, 1090 GE Amsterdam, The Netherlands Accepted 1 June 2006 Available online 25 July 2006 Abstract To investigate underlying learning mechanisms in relation to the development of dyslexia, event-related potentials to visual standards were recorded in five-year-old pre-reading children at-risk for familial dyslexia (n = 24) and their controls (n = 14). At the end of second grade the children aged 8 years were regrouped into three groups according to literacy level and risk factor. Single-trial analyses revealed N1 habituation in the normal-reading controls, but not in the normal-reading at-risks, and a N1 amplitude increase in the group of poor- reading at-risks and poor-reading controls. No P3 habituation was found in either group. The normal-reading at-risk group exhibited the longest N1 and P3 latencies, possibly compensating for their reduced neuronal activity during initial information extraction. In contrast, the poor-reading group only showed prolonged P3, and their increase in (initial small) N1 amplitude together with normal N1 latencies, suggests inefficient processing in an early time window, which might explain automatisation difficulties in dyslexic readers. Ó 2006 Elsevier Inc. All rights reserved. Keywords: Dyslexia; Habituation; Event-related potential; Single trial; Visual; N1; P3; Children 1. Introduction It is internationally recognised that dyslexia is neurobio- logical in origin and characterised by slow and inaccurate reading as well as poor spelling. These difficulties are often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction (Goswami, 2003; Lyon, Shaywitz, & Shaywitz, 2003). Up to 10% of the population shows mild to severe symptoms of dyslexia. In the case of a family-related history of dyslexia preva- lence is estimated between 33% and 50% (Pennington & Lefly, 2001). Having at least one dyslexic parent forms a considerable risk for a young child to develop dyslexia him- self (Gilger, Hanebuth, Smith, & Pennington, 1996). Over the years a strong consensus has arisen among investigators that reading is primarily a linguistic skill and that the cen- tral difficulty in dyslexia reflects a deficit within the lan- guage system, in particular a phonological deficit (e.g., Lyon et al., 2003; Pennington, 1990; Ramus et al., 2003; Vellutino, Fletcher, Snowling, & Scanlon, 2004). Neuro- biological evidence supporting this hypothesis comes from a large amount of literature on reading disability in adults and children, describing dysfunction in particular left hemi- sphere posterior brain systems (e.g., Helenius, Tarkiainen, Cornelissen, Hansen, & Salmelin, 1999; Paulesu et al., 2001; Rumsey, Andreason, Zametkin, & Aquino, 1992; Rumsey et al., 1997; Shaywitz et al., 2002; Silani et al., 2005; Simos, Breier, Fletcher, Bergman, & Papanicolaou, 2000), considered to be critical in the development of skilled, automatised reading (Lyon et al., 2003). In comparison to the abilities of normal-reading chil- dren, it is evident that the reading and spelling of dyslexic children lack automaticity, in particular indicated by rela- tively slow response rates on measurements of (repeated) reading. For example, it has become clear that although familiar words may be processed accurately, the processing 0093-934X/$ - see front matter Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.bandl.2006.06.006 * Corresponding author. Fax: +31 20 5251200. E-mail address: a.g.f.m.regtvoort@uva.nl (A.G.F.M. Regtvoort). www.elsevier.com/locate/b&l Brain and Language 98 (2006) 319–331