The time course of the lexicality effect during reading aloud: impact of block displays and task instructions

The time course of the lexicality effect during reading aloud: impact of block displays and task instructions

First Author: --
Additional authors/chairs: 
Pascal Zesiger; Marjolaine Cohen; Marina Laganaro
Keywords: Reading, reading strategies, visual word recognition, ERP, French
Abstract / Summary: 

Purpose. The time course of the lexicality effect is highly debated, with ERP studies reporting effects as early as in the N170 time window, while others suggest later effects (i.e., around 300-400 ms). However the time course of the lexicality effect has mostly been investigated using lexical decision tasks, which highlight the difference between words and pseudowords, thus possibly biasing the results. The aim of the present study was to investigate the time course of the lexicality effect in reading aloud, and to determine whether it is affected by block displays and task instructions.
Method. Nineteen French-speaking adults performed two reading aloud tasks in which words and pseudowords were displayed in separated blocks (with specific task instructions for each kind of stimulus type) or in mixed blocks (without any specific instructions concerning stimulus type). EEG was recorded continuously using 128 channels and both amplitude waveform and topographic analyses were performed on ERP data.
Results. When words and pseudowords were displayed in separated blocks, a lexicality effect appeared as early as in the P100/N200 time window, suggesting a difference in the visuo-orthographic analysis when stimulus type was predictable. In contrast, when words and pseudowords were displayed in mixed blocks, later lexicality effects were observed (i.e., around 300 ms).
Conclusions. Taken together, our main finding suggests that the time course of the lexicality effect is highly influenced by stimulus display and task instructions and warns against experimental bias in investigating this effect.