This lack of affective modulation of the startle response has been documented previously in studies that investigated affective reactivity in both clinically and nonclinically depressed individuals (Allen, Trinder, & Brennan, 1999; Dichter, Tomarken, Shelton, & Sutton, 2004; Dichter & Tomarken, 2008; Forbes, Miller, Cohn, Fox, & Kovacs, 2005; Kaviani et al., 2004; Larson, Nitschke, & Davidson, 2007; Mneimne, McDermut, & Powers, 2008). Four studies found that while the startle responses of nondepressed individuals reflected the prototypical valence modulation, the startle responses of patients who were diagnosed with major depressive disorder were neither attenuated by pleasant stimuli nor potentiated by unpleasant stimuli (Allen et al., 1999; Dichter et al., 2004; Dichter & Tomarken, 2008; Forbes et al., 2005). Furthermore, there were some indications that the relationship between depression and affective modulation of the startle response might be moderated by the severity of the patients’ depressive symptoms. That is, the lack of affective modulation of startle response was only found in highly depressed patients (Allen et al., 1999; Kaviani et al., 2004) and in patients who reported a high level of anhedonic symptoms (Kaviani et al., 2004).
