טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentSinai Alon
SubjectEvoked Potentials in First and Second Language Processing:
The Time Course of Linguistic Processing
DepartmentDepartment of Medicine
Supervisor Professor Emeritus Hillel Pratt


Abstract

The purpose of this research was to study processing of first and second language in the human brain. Event-Related brain potentials (ERPs) were recorded from scalps of native Hebrew speakers that know English as a second language. In the first experiment, under attention distraction, the subjects listened to pairs of words and pseudowords in Hebrew and English. In the main experiment, with subjects attending, pairs of stimuli included the same categories along with words in Hebrew and English each in the other language accent, and words played backwards. Analysis included ERP peaks, principal component analysis and source estimation using the LORETA algorithm.

The results showed that the early (until 200 msec) ERP components are sensitive to acoustic differences between languages as voice onset time. First language stimuli drew more automatic attention than second language stimuli. Partial semantic processing was evident in the absence of awareness. The priming effects indicate processing of the linguistic context even without awareness.

Linguistic and non-linguistic stimuli evoked different responses. Language-specific acoustic factors, such as accent, were found influential on the early part of processing. Later stages showed differences in processing first and second language. Activation in the auditory cortex was observed beginning at 40 ms and continued until 750 ms after stimulus onset. Hemispheric dominance fluctuated between left and right temporal regions. Second language involved more right hemisphere activity than first language. Priming effects were observed and manifested, in early stages, in weaker activation of regions that were activated previously by the prime, while in later times activation pattern tended to be similar to the prime.

The processing pattern beginning by sorting acoustic features and then analyzing properties of specific stimuli are in line with the concept of speech being a particular case of auditory object processing.