  We study the action of mirror symmetry on two-dimensional N=(2,2) effective
theories obtained by compactifying Type IIA string theory on Calabi-Yau
fourfolds. Our focus is on fourfold geometries with non-trivial three-form
cohomology. The couplings of the massless zero-modes arising by expanding in
these forms depend both on the complex structure deformations and the Kahler
structure deformations of the Calabi-Yau fourfold. We argue that two
holomorphic functions of the deformation moduli capture this information. These
are exchanged under mirror symmetry, which allows us to derive them at the
large complex structure and large volume point. We discuss the application of
the resulting explicit expression to F-theory compactifications and their weak
string coupling limit. In the latter orientifold settings we demonstrate
compatibility with mirror symmetry of Calabi-Yau threefolds at large complex
structure. As a byproduct we find an interesting relation of no-scale like
conditions on Kahler potentials to the existence of chiral and twisted-chiral
descriptions in two dimensions.
