Although Selinker did not, in his original article, explicitly state what has now come to be known as the interlanguage hypothesis, he laid the groundwork for a number of studies based on this notion. It can succinctly be stated as follows:
There exists a separate linguistic or psycholinguistic system (interlanguage)
which forms in the mind of the learner and may take the form of a
pidgin and which may develop into a language in its own right.