The paper addresses both issues of first language attrition and second language acquisition in the context of two mutually intelligible languages from a psycholinguistic perspective. It investigates how native speakers of Slovak living long-term in Czechia process and produce Slovak and Czech words.
Three groups of participants were tested using lexical decision task and picture naming task. The experimental group (N=64) comprised native speakers of Slovaks living in Czechia, the Slovak control group consisted of Slovaks living in Slovakia (N=47) and the Czech control group comprised native speakers of Czech living in Czechia (N=46).
Both experiments had a Czech and a Slovak version. The experimental group and the Slovak control group participated in both versions.
The Czech control group took part in the versions with Czech stimuli. The stimuli were divided into three groups: (i) identical cognates, (ii) non-identical cognates, and (iii) differing words.
Reaction times to Slovak stimuli in both experiments were significantly longer for differing words as opposed to cognates, but only in those participants from the experimental group whose use of Slovak is more limited, use of Czech more extensive and who have been living in Czechia for a long period of time. The performance of this group of participants in experiments using Czech stimuli were more similar to that of the native speakers of Czech.
The study thus gives evidence of a) first language attrition and b) diminishing cognate effect which is associated with conditions supporting second language acquisition in two closely related languages.