Alpha and theta band dynamics related to sentential constraint and word expectancy

ABSTRACT

Despite strong evidence for prediction during language comprehension, the underlying mechanisms, and the extent to which they are specific to language, remain unclear. Re-analysing an event-related potentials study, we examined responses in the time-frequency domain to expected and unexpected (but plausible) words in strongly and weakly constraining sentences, and found results similar to those reported in nonverbal domains. Relative to expected words, unexpected words elicited an increase in the theta band (4–7 Hz) in strongly constraining contexts, suggesting the involvement of control processes to deal with the consequences of having a prediction disconfirmed. Prior to critical word onset, strongly constraining sentences exhibited a decrease in the alpha band (8–12 Hz) relative to weakly constraining sentences, suggesting that comprehenders can take advantage of predictive sentence contexts to prepare for the input. The results suggest that the brain recruits domain-general preparation and control mechanisms when making and assessing predictions during sentence comprehension.

KEYWORDS:

• Prediction
• language
• sentence comprehension
• pre-stimulus alpha
• frontal theta

Disclosure statement

The authors report no potential conflict of interest.

Notes

1. Descriptions of cluster extent are provided as an indication of the most likely contributors to each effect, but should not be taken to indicate effect onsets and offsets in time, space, or frequency. This is because the statistical test only controls the false alarm rate under a non-specific null hypothesis, namely that of no differences between the complete datasets in the two conditions (Maris, 2012).

2. It should be noted that, although the ERPs show a positive-going difference for this contrast (see Figure 2), in the original study (Federmeier et al., 2007) and its follow-ups, the focus had been on the contrast between unexpected words in strongly versus weakly constraining contexts, which more cleanly separates constraint and cloze probability. However, the expected versus unexpected comparison tested here is more similar to what has been examined in non-language tasks, and exploring similarities was a major aim of this study.

Additional information

Funding

This work was supported by the NIH under Grant number AG026308 to K.D.F.; and by a James S. McDonnell Foundation Scholar Award to K.D.F.