Hi Brian!

To my mind, physical reponses are not problematic for the epiphenomenalist, if these responses are not physical but mental. Nevertheless, the very deep philosophical problem remains: how is mentality in causal connection with physicality?

If 1) mental states such as sensations and images,
  2) cognition such as deciding and perceiving and
  3) emotions such anger and joy

are mental entities, then, for the epiphenomenalist, there is no the following problem: how do mental items cause particular physical responses? In brief, a causality would be the following: a sensation of redness (mental) causes deciding to hold out one's hand (mental).

Thus, why does one name cognitive behaving, for example deciding to pick up, physical? Many cognitive psychologists consider them as psychological as mental states in general.

Finally, if there is no similarity between A and B, how is there a causal connection between A and B? And mentality and physicality are ontologically distinct entities. They are not similar, if I understand their meanings correctly. So, a psycho-physical causality seems to be an inference for many present philosophers. They don't perceive it.