Naming processes in reading and spelling disorders: An electrophysiological investigation

•Neurophysiology (event-related potentials) of naming processes in reading (RD; F 81.0) and spelling disorder (iSD; F 81.1).•Impaired lexical access in RD compared to typically developing (TD) children, reflected in a reduced P2 amplitude.•Comparable neurophysiological naming processes in TD and iSD. Reading fluency deficits characteristic for reading disorders (RD; F81.0) have been shown to be strongly associated with slow naming speed (e.g. in rapid automatized naming tasks). In contrast, children with an isolated spelling disorder in the context of unimpaired reading skills (iSD; F81.1) show naming speed task performances that are similar to typically developing (TD) children. However, the exact nature of the naming speed deficit and its relation to RD and the question whether children with iSD are also on the neurophysiological level similar to TD children is still unresolved. The time-course and scalp topography of event-related potentials (ERP) activity recorded during a delayed digit-naming task was investigated in ten-year-old children with RD and iSD compared to a TD group. ERP activity differed between the RD and the TD group at around 300 ms after stimulus presentation (left occipito-temporal P2). In contrast, there were no neurophysiological differences between the TD and the iSD group. The P2 component correlated with behavioural performance on the RAN task. Slow naming speed in RD might result from a slowed-down access and prolonged processing of the word (lexical) form. The study establishes a relation between neurophysiological processes of naming tasks and RD.