We study the influence of the intensity of light and the wavelength of an imposed parallel striped mask on the development of striped Turing patterns. Depending on the ratio R = lambda(F)/lambda(P) of the wavelength of the mask to the wavelength of the natural pattern and on the amplitude of forcing, stripes develop parallel or perpendicular to the orientation of the mask. For R near 1.5 or 3, zigzag patterns develop. When weak forcing is applied, stripe splitting is observed for R near 2. For strong forcing, stripe splitting occurs over a wider range of R, and two sequences of splitting are observed when R = 4. At large R, fingers of spreading patterns develop, which propagate and reconnect to form stripes perpendicular to the mask orientation.