I don't know if anyone has heard of the Gamma-Lambda effect. I did a little research into this sometime ago. Average gradient is affected by the wavelength of light. Blue light tends to decrease the gradient while green tends to increase the film gradient. Red and white light tends to fall somewhere in between. My tests confirmed this. I tested nine films using tri-color filters with my EG&G. Hold times were identical and the film was processed together in a dip & dunk. The differences weren't great but there were differences.
This is an example from the those tests.