The effect of depolarizing collisions on the shape of the spectrum in the quadratic Stark effect or anomalous Zeeman effect is conSidered. It is shown that collisions may result in merging (collapse) of the allowed spectral components. It is found that exchange between the Stark and Zeeman components can be observed by analyzing the structure of the Lamb dip. An additional (certral) dip is detected. Methods for experimental determination of the collisional relaxation constants and of the parameters of the Stark and Zeeman structures of the spectrum are mentioned. (auth)