I have been studying shame for several years using the Internalized Shame Scale which I developed. When the focus of emotional phenomena becomes solely fixed on cognitions the essential role of the biologically based affects can become lost in the process. It is relatively easy to conceptualize guilt in cognitive terms because guilt implies the crossing of a boundary, the violation of some standard, be it external or internal, and as such requires some cognitive development for guilt to appear. The confusion of guilt with shame is legion it seems. In Silvan Tomkins' affect theory shame is the primary affect.
Guilt is a variant of that affect.
Much of what Weiss and his associates is describing is more properly understood as shame affect appearing as one or another of the four typical defenses described by Nathanson as the Compass of Shame. The research which purports to establishd guilt as a more significant variable in psychopathology than shame is, of course, based on the Weiss questionnaire which I have not seen and cannot, therefore, properly evaluate. But the theoretical structure of the questionnaire makes it likely that the items are likely to be substantially correlated with measures of shame, again confounding conclusions about guilt. In any case, we are dealing with a significantly painful emotion that has biological roots in the case of shame. To take a purely cognitive view of emotion by concocting several variants of guilt, labeling guilt as a primary emotion, and then arguing that it supercedes shame as a precursor to pathology flies in the face of much of the research and theory that has focused on shame as a primary human emotion.