Differential development of attention and executive functions in 3- to 12-year-old Finnish children

The developmental sequence of attention and executive functions (EFs) was studied by utilizing normative data from four hundred 3- through 12-year-old Finnish children. Data from 10 subtests measuring impulse control and inhibition of irrelevant responses, auditory and visual attention, visual search, planning, and verbal and visual fluency were included. The development proceeded sequentially, from motor inhibition and impulse control to functions of selective and sustained attention, and finally to EFs of fluency. Significant relations between gender and development and between parent education and development were found in several subtests. In a factor analysis, inhibition, auditory attention, visual attention, and the EF of fluency clustered into separate factors. The developmental staging and clustering of functions suggests that, although inhibition, attention, and EFs are highly interrelated cognitive functions, their developmental sequences are separate from one another. The development of basic inhibitory functions precedes the development of more complex functions of selective attention, and EFs continue to develop into adolescence.

Rate of information segregation in developmentally dyslexic children

Slowed processing of sequential perceptual information is related to developmental dyslexia. We investigated this unimodally and crossmodally in developmentally dyslexic children and controls ages 8-12 years. The participants judged whether two spatially separate trains of brief stimuli, presented at various stimulus onset asynchronies (SOA) in one or two senses, were synchronous or not. The stimulus trains consisted of light flashes in vision, clicks in audition, and indentations of the skin in the tactile sense. The dyslexic readers required longer SOAs than controls for successful performance in all six comparisons. The crossmodal spatiotemporal resolution of the groups differed more than unimodal performance. The dyslexic readers' segregation performance was also less differentiated than that of the controls. Our results show that not only sensory but also polysensory nonverbal information processing is temporally impaired in dyslexic children.