[1]: 240 Polish science fiction scholars Andrzej Niewiadowski [pl] and Antoni Smuszkiewicz [pl] defined inner space as "a category introduced to science fiction by representatives of the New Wave to designate internal, mental experiences as imaginary worlds with no connection to the real world".
They also note that "fantastic images painted by [New Wave artists] are... projections of mental states, symbols of unspecified longings and anxieties of modern people".
[3] She notes that this genre arose when some writers became critical of poorly defined heroic characters and "romantic idealization of the cosmic 'borderland'".
[7]: 489–490 [8] Brian Ash noted that science fiction works dealing with psychological topics existed before the concept was coined and popular.
As well, the mechanics of Gottfried Wilhelm Leibniz's ‘mill argument’ pointing towards the themeatics of entering inside a working mind as if it were physical space.
He notes that Inception marked "the transition of inner space fiction from a marginal genre (SF literature) to a viable mainstream (Hollywood cinema)".