“…explain the individual differences in temperament traits'' (p. 135). In other words, individual differences in psychological reactivity (measured using self-report methods) are merely proxies for physiological traits (for examples of PSA research using measures of psychological reactivity, see Clay, Fisher, Xie, Horvath, Moss, Xie, Sawyer, & Behnke, 2004;Kopecky, Sawyer, & Behnke, 2004;Winters et al, 2007).…”