This study explores the use of task that can be applied in a uniform fashion across
different languages to compare levels of vocabulary development in foreign language
learning. Experiment 1 tested native speakers of Russian and German and demonstrated the
basic comparability of subjects’ judgments for both words and nonwords. The results for
Russian showed an influence of word length which can be understood in terms of the
Orthographical Depth Hypothesis. Experiment 2 applied the same task to learners of
Russian and German and found that learners of Russian had achieved a lower level of
vocabulary control than learners of German at comparable language exposure levels. This
disadvantage for Russian can be attributed to the novelty of the Cyrillic graphemic system
which restricts the accessibility of written language input at early stages. There was a
nonlinear increase over time in word sensitivity that can be attributed to the increasing
contribution of lexical plausibility factors at later stages of learning. Also, the lexical
decision task appeared to be sensitive to inhibitory effects of concurrently studied
languages, as well as decay due to lack of regular exposure. Together, these results indicate
that the lexical decision task can be a useful tool for the assessment and crosslinguistic
comparison of lexical development in foreign language learning.