Is there a cost when predictions are not met? A VWP study investigating L1 and L2 speakers

Research has found that both first language (L1) and second language (L2) speakers make predictions about upcoming linguistic information, with predictive behaviour being impacted by individual differences and methodological factors. However, it is not clear whether a cost is incurred when a prediction is made, but not met. L2 speakers have less experience with their L2 and parsing can be cognitively demanding, which together may lead L2 speakers to incur prediction costs differently relative to L1 speakers. In this study using the visual world paradigm, we test whether L1 and L2 speakers predict in the same way, within the same time frame, and incur the same costs if predictions are not met. We also explore the role of proficiency and speech rate. We found that both groups predict in a similar way and within a similar time frame. In addition, neither group incurred a prediction cost when the target was the most likely alternative, though L2 speakers take longer to shift their attention to the target object when predictions are not met. We argue that this reflects a slowing of lexical access rather than a specific cost of prediction. We only found prediction differences when speech rate was included in the analysis, highlighting the importance of attending to speech rate in studies using the visual world paradigm. Overall, this study supports research showing that both L1 and L2 speakers may make multiple partial predictions about upcoming information rather than predicting one specific lexical candidate while inhibiting less likely lexical candidates.