Children with developmental dyslexia show an increased variable foreperiod effect

Abstract

ABSTRACT Dyslexia has been linked to timing deficits by previous studies. Here, we investigated specifically two types of implicit temporal adaptation abilities in children with dyslexia, namely the variable foreperiod effect and time-based expectancy. Eighteen children with dyslexia and eighteen typically developing children with ages ranging from 8 to 13 participated. They completed a binary choice reaction time task in which short (1,000 ms) or long (3,000 ms) durations of a visual cue (i.e. foreperiod) predicted with a probability of .9 the direction of a centrally presented arrow. Dyslexic children showed a significantly more pronounced variable foreperiod effect (i.e. responding faster to long foreperiods than to short foreperiods) than normally developing children. However, there were no significant differences between groups in the time-based expectancy effect (i.e. responding differently to likely combinations of foreperiod and target than to unlikely combinations). The results are discussed in the context of time-deficit theories of dyslexia.