The human brain can quickly and accurately split speech units from continuously changing auditory signals, then recognize correct words and integrate them with the preceding context to understand speech, involving hierarchical and dynamic interaction processes. Prediction, operating by pre-activation, may be one of the intrinsic mechanisms in speech comprehension. Production-based prediction may be the underlying mechanism in making active prediction, and the theory claims that comprehenders use their production system to predict upcoming words, which can occur at any level and stage, with lower-level information following higher-level information. Although many studies have explored the contents of lexical prediction and verified the pre-activation effect at multiple levels, the relevant experimental paradigms and the nature of hierarchical speech prediction are not yet been fully understood. Therefore, the present study conducted three experiments to explore the validity of the visual world paradigm as well as to investigate the relationship between high-level semantic prediction and low-level phonological prediction, gradually.
Experiment 1 focused on the possible influence of the preview duration on the preactivation effect in a visual world paradigm experiment. Results showed that shortening the preview to 1000 ms affected the onset of the pre-activation effect but still reproduced the effect similar to the previous study which was conducted under 2000 ms preview, indicating that changing the preview did not fundamentally affect the emergence of the semantic and phonological pre-activation effect, which reveals that the lexical pre-activation effect is somewhat robust. Experiment 2 focused on the influence of sentence context on the semantic pre-activation effect, and found that the experimental effect was stronger when the semantically related words were more easily integrated with the sentence context, so the semantic pre一activation effect at this time was essentially a joint outcome of contextual integration and lexical prediction rather than the pre-activation effect alone, suggesting that the contextual integration factor may interfere with the interpretation of the semantic pre一activation effect when using visual world paradigm to explore lexical prediction. Using materials that could exclude the influence of sentence context, Experiment 3 focused on the time course of semantic and phonological pre-activation effect and the hierarchical relationship between them again. Results showed that the semantic pre-activation effect occurred earlier and was stronger than the phonological pre-activation effect, which is in line with the hypothesis of the prediction-by-production theory, supporting the statement that "the pre-activation at lower levels follows pre-activation at higher levels".
In conclusion, this study explored the cognitive process of lexical prediction during speech comprehension. After determining the validity of the experimental paradigm and excluding contextual interference, this study observed the existence of semantic and phonological pre-activation effects and characterized their differences in time course and effect strength, providing experimental evidence to support the prediction-by-production theory. This study helps convey a contribution to the future exploration of the cognitive mechanism of speech comprehension and prediction and provides a potential reference for fields of brain-inspired AI.
修改评论