Theta activity and cognitive functioning: Integrating evidence from resting-state and task-related developmental electroencephalography (EEG) research.

The theta band is one of the most prominent frequency bands in the electroencephalography (EEG) power spectrum and presents an interesting paradox: while elevated theta power during resting state is linked to lower cognitive abilities in children and adolescents, increased theta power during cognitive tasks is associated with higher cognitive performance. Why does theta power, measured during resting state versus cognitive tasks, show differential correlations with cognitive functioning? This review provides an integrated account of the functional correlates of theta across different contexts. We first present evidence that higher theta power during resting state is correlated with lower executive functioning, attentional abilities, language skills, and IQ. Next, we review research showing that theta power increases during memory, attention, and cognitive control, and that higher theta power during these processes is correlated with better performance. Finally, we discuss potential explanations for the differential correlations between resting/task-related theta and cognitive functioning, and offer suggestions for future research in this area.

Out of sight, out of mind: Foveal processing is necessary for semantic integration of words into sentence context.

Word recognition begins before a reader looks directly at a word, as demonstrated by the parafoveal preview benefit and word skipping. Both low-level form and high-level semantic features can be accessed in parafoveal vision and used to promote reading efficiency. However, words are not recognized in isolation during reading; once a semantic representation is retrieved, it must be integrated with the broader sentence context. One open question about parafoveal processing is whether it is limited to shallow stages of lexico-semantic activation or extends to semantic integration. In the present two-experiment study, we recorded event-related brain potentials in response to a sentence-final word that was presented in foveal or parafoveal vision and was either expected, unexpected, or anomalous in the sentence context. We found that word recognition, indexed by the N400, ensued regardless of perception location whereas identification of the semantic fit of a word in its sentence context, indexed by the late positive component, was only observed for foveally perceived but not parafoveally perceived words. This pattern was not sensitive to task differences that promote different levels of orthographic scrutiny, as manipulated between the two experiments. These findings demonstrate separate roles for parafoveal and foveal processing in reading. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Are eye movements and EEG on the same page?: A coregistration study on parafoveal preview and lexical frequency.

Readers extract visual and linguistic information not only from fixated words but also upcoming parafoveal words to introduce new input efficiently into the language processing pipeline. The lexical frequency of upcoming words and similarity with subsequent foveal information both influence the amount of time people spend once they fixate the word foveally. However, it is unclear from eye movements alone the extent to which parafoveal word processing, and the integration of that word with foveally obtained information, continues after saccade plans have been initiated. To investigate the underlying neural processes involved in word recognition after saccade planning, we coregistered electroencephalogram (EEG) and eye movements during a gaze-contingent display change paradigm. We orthogonally manipulated the frequency of the parafoveal and foveal words and measured fixation related potentials (FRPs) upon foveal fixation. Eye movements showed primarily an effect of preview frequency, suggesting that saccade planning is based on the familiarity of the parafoveal input. FRPs, on the other hand, demonstrated a disruption in downstream processing when parafoveal and foveal input differed, but only when the parafoveal word was high frequency. These findings demonstrate that lexical processing continues after the eyes have moved away from a word and that eye movements and FRPs provide distinct but complementary accounts about oculomotor behavior and neural processing that cannot be obtained from either method in isolation. Furthermore, these findings put constraints on models of reading by suggesting that lexical processes that occur before an eye movement program is initiated are qualitatively different from those that occur afterward. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Semantic parafoveal processing in natural reading: Insight from fixation-related potentials & eye movements.

Prior research suggests that we may access the meaning of parafoveal words during reading. We explored how semantic-plausibility parafoveal processing takes place in natural reading through the co-registration of eye movements (EM) and fixation-related potentials (FRPs), using the boundary paradigm. We replicated previous evidence of semantic parafoveal processing from highly controlled reading situations, extending their findings to more ecologically valid reading scenarios. Additionally, and exploring the time-course of plausibility preview effects, we found distinct but complementary evidence from EM and FRPs measures. FRPs measures, showing a different trend than EM evidence, revealed that plausibility preview effects may be long-lasting. We highlight the importance of a co-registration set-up in ecologically valid scenarios to disentangle the mechanisms related to semantic-plausibility parafoveal processing.