Middle-schoolers' reading and lexical-semantic processing depth in response to digital and print media: An N400 study.

We report the first use of ERP measures to identify text engagement differences when reading digitally or in print. Depth of semantic encoding is key for reading comprehension, and we predicted that deeper reading of expository texts would facilitate stronger associations with subsequently-presented related words, resulting in enhanced N400 responses to unrelated probe words and a graded attenuation of the N400 to related and moderately related words. In contrast, shallow reading would produce weaker associations between probe words and text passages, resulting in enhanced N400 responses to both moderately related and unrelated words, and an attenuated response to related words. Behavioral research has shown deeper semantic encoding of text from paper than from a screen. Hence, we predicted that the N400 would index deeper reading of text passages that were presented in print, and shallower reading of texts presented digitally. Middle-school students (n = 59) read passages in digital and print formats and high-density EEG was recorded while participants completed single-word semantic judgment tasks after each passage. Following digital text presentation, the N400 response pattern to moderately-related words indicated shallow reading, tracking with responses to words that were unrelated to the text. Following print reading, the N400 responses to moderately-related words patterned instead with responses to related words, interpreted as an index of deeper reading. These findings provide evidence of differences in brain responses to texts presented in print and digital media, including deeper semantic encoding for print than digital texts.

Evaluation of mismatch negativity as a marker for language impairment in autism spectrum disorder.

BACKGROUND: The identification of an early and objective marker of language impairment in autism spectrum disorder (ASD) has the potential to lead to earlier language intervention for affected children. The mismatch negativity (MMN), a passive auditory evoked potential, offers insight into the brain's ability to direct attention to novel sounds. Since exposure to speech is necessary for learning to map meaning onto phonemes, we predicted slower MMN responses to speech sounds would indicate presence of language impairment in ASD. METHODS: We explored the relationship between MMN latency in children ages 5-10 with ASD plus language impairment (ASD + LI), ASD minus language impairment (ASD-LI), and typically developing children (TD) during an auditory oddball experiment presenting speech and pure tone sounds. RESULTS: Contrary to our prediction, children with ASD + LI demonstrated decreased MMN latency in the left hemisphere in response to novel vowel sounds compared to children with ASD-LI and TD controls. Parent responses to the Sensory Experiences Questionnaire revealed that all participating individuals with ASD were hypersensitive to sounds. CONCLUSIONS: Our results lend support to the theory that some children with ASD + LI have increased connectivity in primary sensory cortices at the expense of connectivity to association areas of the brain. This may account for faster speech sound processing despite low language scores in these children. Future studies should focus on individuals with language impairment and hyper-or hyposensitivity to sounds.

Visually Evoked Response Differences to Contrast and Motion in Children with Autism Spectrum Disorder.

High-density electroencephalography (EEG) was used to examine the utility of the P1 event-related potential (ERP) as a marker of visual motion sensitivity to luminance defined low-spatial frequency drifting gratings in 16 children with autism and 16 neurotypical children. Children with autism displayed enhanced sensitivity to large, high-contrast low-spatial frequency stimuli as indexed by significantly shorter P1 response latencies to large vs. small gratings. The current study also found that children with autism had larger amplitude responses to large gratings irrespective of contrast. A linear regression established that P1 adaptive mean amplitude for large, high-contrast sinusoidal gratings significantly predicted hyperresponsiveness item mean scores on the Sensory Experiences Questionnaire for children with autism, but not for neurotypical children. We conclude that children with autism have differences in the mechanisms that underlie low-level visual processing potentially related to altered visual spatial suppression or contrast gain control.