We report on the layer coupling for the electric field induced ferroelectric ordering in antiferroelectric liquid crystals (AFLCs). On approaching the field induced antiferroelectric-ferro electric (AF-FO) transition, the electrooptic response abruptly increases, reaches a maximum, and then saturates with increasing the electric field. Moreover, the associated switching time exhibits two sharp peaks, indicating the existence of an intermediate ferrielectric-like phase in the middle of the AF-FO transition. The anomaly observed is described in terms of layer coupling in a simplified model which contains interactions of both the nearest (N) and next nearest (NN) neighboring layer pairs. The coupling constants for the N and NN neighboring layers are estimated.