This has always been somewhat of a gray area in the canon from what I have seen. Now it is commonly understood that Pariahs have no souls. This of course manifests itself as them having no presense in the Warp. However in a classical sense a soul is where feelings, empathy and love come from as well. So, the question is do Pariah's and other soulless being have emotions like the rest of us, or does their lack of soul render them numb?