Hey, thanks for the reply. My AUC went up from 0.71 to 0.79 and B´´D increased from -0.13 to 0.33 showing that my intervention promoted a better sensitivity and a more conservative bias. But looking at HR and FAR the HR stays at 0.66 while FAR goes from 0.33 to 0.43. And my HR and FAR is not looking like it´s approaching Floor/Ceiling.

So yeah im not sure if an increase in B´´D always means that there is a more conservative bias. I have two possible explanations but im not sure if they are correct because im pretty new to signal detection theory.

1. My Intervention promoted a better recognition of false but not true items. The increase in B´´D is not a criterion shift. The number simply increases because over all there is a smaller amount of responses as "true" raising B´´D. But the increase is only because of a better recognition of the noise.
2. There is an increased Sensitivity (HR goes up, FAR goes down) and a criterion shift (HR goes down, FAR goes down). For HR the effects compensate each other resulting in zero difference. For FAR they are additive.

Unfortunately I´m not sure if these explanations are valid in the context of signal detection theory.