[1][2] Vainikka received her Ph.D. in Linguistics in 1989 from the University of Massachusetts, Amherst, with a dissertation on Finnish syntax, one of the first on this topic.
[4] At the time of Vainikka's death from cancer in 2018, she was an adjunct professor at the University of Delaware in the Department of Linguistics and Cognitive Science.
[6] Vainikka was most notable within linguistics and SLA for developing the Minimal Trees Hypothesis with Martha Young-Scholten,[7] an "important theory,"[8] where 'tree' is a metaphor of syntax for the branching structure showing how words of a phrase or sentence co-relate.
Whereas many researchers lean towards a 'Full Transfer' view in which all the L1 grammar transfers[10] - i.e. the initial state of the L2 is the final state of the first - Young-Scholten and Vainikka argued that only lexical categories (e.g. the noun phrase) are drawn from the L1, and that functional categories (e.g. the inflectional phrase that represents tense) do not; rather, the learner 'grows' new ones because they start their L2 acquisition with only a 'minimal' syntactic tree.
Several competing accounts for the role of transfer and universal grammar persist in SLA; the Minimal Trees Hypothesis remains particularly controversial, and has been strongly critiqued in syntactic research on both empirical and conceptual grounds: some researchers argue that linguistic behaviour does not follow the model,[11] and others claim that it is theoretically misconceived.