Regional accent biases in 27 Essex five-year-olds are investigated. This study is the first to analyse implicit language attitudes by measuring children’s neural activity (event-related potentials) while they take part in an Implicit Association Test. Both measures find a preference towards the prestigious accent, Standard Southern British English (SSBE), which is associated with cleverness (CLEVER). A late positive potential in the brain data for the association of the familiar, low-prestige Essex accent with CLEVER suggests the children also have a positive association with their home accent. The association between the less familiar, low-prestige Yorkshire accent and either CLEVER or NOT-CLEVER depends on the measure. Differences in the results are found relating to the children’s accent exposure; those with a more heterogenous group of caretakers show more positive bias towards all three accents overall. Consequences for modelling the development of language attitudes are discussed.