Basora, A. 1 , Jin, Y. . 1 , Martin, I. 2 & Sebastián, N. . 1
1 Cognition and Brain Research Unit, UPF
2 Cancer Epigenetics and Biology Program, IDIBELL
It is known that humans differ in their ability to master a second language (L2). Previous studies showed that the age of acquisition, the amount of experience and the motivation are important factors in second language learning. However, individual differences in language learning ability are usually understood in terms of “aptitude”, which is related to genetic differences. It is unclear what is the determinant factor in mastering a L2: environment or genes? In this study, first, we aimed at finding a new index to estimate similarities in twins’ speech perception ability and, second, we also wanted to find the relevance of the environmental factors in L2 perception. In order to do that, we recorded event-related potentials (ERPs) from both monozygotic (MZ) and dizygotic (DZ) twins. They performed a task related to speech and acoustic change detection, specifically, native (/o/-/e/) and non-native (/o/-/ö/) phonetic contrasts. Two different analyses (Peak and Wavelet) were carried out to compare the brain activity from each pair of twins. For Wavelet analysis two indexes were created: the Similarity Distance Index and the Within Population Rate. The results showed that (1) the Similarity Distance Index could be a good measure to estimate similarities in twins’ speech perception ability and (2) MZ twins were more similar than DZ twins in phoneme perception.