Dissociation of the Confounding Influences of Expectancy and Integrative Difficulty Residing in Anomalous Sentences in Event-related Potential Studies

Summary

We present a protocol to dissociate the intertwining factors of integrative difficulty and unexpectedness in semantically anomalous sentences by applying multiple repetitions to enhance participant's expectancy for anomalous sentences. The dissociation helps to investigate the major contributor of elicited event-related potentials (ERP) effects such as N400 in language studies.

Abstract

The confounding factors of unexpectedness and semantic integration difficulty naturally residing in anomalous sentences in language studies make it difficult to determine the underlying processing mechanism of ERP components. Unlike the traditional static approach of manipulating expectancy through corpus frequency or cloze probability, this protocol proposes a dynamic method to enhance participants' expectancy for rarely-met anomalous sentences by multiple repetitions while maintaining their semantic integration difficulties. To address the time cost increase resulting from multiple repetitions, this protocol proposes to repeat only the strictly simplified core structure extracted from the anomalous sentence before presenting the semantically enriched, much more informative complete anomalous sentence containing the anomalous core structure to reinitiate the semantic integration processing. The complete anomalous sentence elicited a P600 effect. It suggests that the participants did not give up processing the anomalous information after repetitions and the same semantic integration difficulty was successfully reinitiated. Importantly, the representative experimental results reveal that the greatly attenuated N400 effect caused by multiple repetitions was not recovered by the follow-up reinitiated semantic integration difficulty. It suggests that the attenuated N400 effect should be mainly attributed to the enhancement of expectancy for anomalous information by multiple repetitions. The experimental results show that this method can effectively enhance participants' expectancy for anomalous sentences while retaining the semantic integration difficulty.

Introduction

Anomalous sentences are widely used by linguists to study online cognitive processing of normal languages. For example, in event-related potentials (ERP) studies, sentences with semantic anomalies (e.g., "He spread the warm bread with socks.") were reported to elicit an N400 effect¹ (but also see some other studies reporting a semantic P600 effect^2,3), while sentences with syntactic difficulties or anomalies (e.g., "The woman persuaded to answer the door…") were reported to elicit a P600 effect^4<....

Protocol

The present protocol was approved by the Institutional Review Board of Tsinghua University.

1. Stimuli construction

1. Construct critical anomalous sentences for the repetition and non-repetition groups
   1. Prepare an adequate number of correct sentences for the construction of anomalous sentences (no less than 40). For example, “These two components were separated by a centrifugal device.” Try to use only emotion-free sentences as.......

Discussion

Experimental results and significance
In the repetition part, the results demonstrated that the N400 effect became smaller and smaller until almost non-existent. The greatly attenuated N400 effect proved that multiple repetitions did significantly modulate the amplitude of N400. However, the results in this part cannot show whether N400 was actually affected by the change of expectancy or semantic integration. The attenuated N400 effect can still be explained differently. One explanation is that ex.......

Materials

Name	Company	Catalog Number	Comments
BrainAmp DC amplifier system (Brain Products GmbH)	Brain Products, Gilching, Germany		BrainAmp S/N AMP13061964DC Input 5.6DC=150mA Operation 7mA Standby
Easycap (Brain Products GmbH)	Brain Products, Gilching, Germany		62 Ag/AgCl electrodes with a configuration of the international 10–20 system of electrode