The type of household a young child grows up in appears to be associated with the way their brain responds to rhyming sounds.
We already know from past research that the processing of sounds is vital to reading ability and that children from less advantageous backgrounds are at increased risk of developing reading problems. This new finding adds the brain jigsaw piece to the reading development puzzle.
Fourteen 5-year-olds had their brains scanned while they judged whether or not words, real and made-up, rhymed with each other. Among the children with wealthier, better educated parents, the difference in amount of activity between the left and right hemispheres tended to be larger while performing this task, than among the children with poorer and/or less educated parents. In other words, among the children whose parents were of higher socioeconomic status, language processing appeared to be more localised to the left hemisphere, as is seen in most adults.
The specific region of the brain showing this difference included an area famously associated with language, known as Broca's area, after its discoverer Paul Broca.
Moreover, the pattern of findings held even after taking into account the children's scores on tests on vocabulary and their awareness of the sounds in words. This means the brain scanning was highlighting links between socioeconomic background and language processing that the behavioural tests were not sensitive to. As well as revealing functional associations, the brain scans also showed that the children's socioeconomic background predicted the amount of brain cell volume in the Broca's area of their brains.
So, why is a child's home environment associated with the way their brain responds to rhyming sounds in particular and, presumably, language processing in general? Rajeev Raizada and colleagues who conducted the research said: "One candidate mechanism that we are currently investigating is the richness of the vocabulary and syntax to which a child is exposed."
RAIZADA, R., RICHARDS, T., MELTZOFF, A., KUHL, P. (2008). Socioeconomic status predicts hemispheric specialisation of the left inferior frontal gyrus in young children. NeuroImage, 40(3), 1392-1401. DOI: 10.1016/j.neuroimage.2008.01.021
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.