Some empirical findings in this area are ambiguous with respect to possible third variables of the kind that can make difficult causal interpretation in studies of job characteristics (see chap. 8). Outcomes apparently deriving from social contagion might be caused at least in part by unmeasured features that are correlated with those inputs. For example, Griffen (1983). pointed our that cues provided about job content in his investigation (see earlier description) were sometimes accompanied by wider employee-supervisor interactions, as conversations developed around a supervisor’s initial remakes. Those conversations could have modified some environmental features such as feedback to an employee or supervisor support. Similarly, the confederate in Barsade’s (2002) study may have transmitted information about additional personal characteristics or opinions beyond merely pleasantness or unpleasantness. (Howover, no evidence of such contaminations was found in postexperimental cheeks.) The two sets of leaders in the research by Sy et al. (2005) could have discussed different issues with their colleagues, not only reflecting a negative or positive mood.