Morphing face discrimination
In the morphing face discrimination task, half of the trials were physically the same (the 0% morph level) and half were different (all other morph levels); therefore, we adopted the signal detection theory (SDT)18 to code the responses into four categories: hits, miss, false alarm, correct rejection, and calculated the perceptual sensitivity index d’, defined as [Z(Hit)-Z(False Alarm)] (See the bottom half of Table 1). We defined “Hit” as responded as “different’ when the comparison face was physically different (“Hit” was computed by averaging across the responses at the 20%, 40%, 60%, and 80% morph levels). “Miss” was responded as “same” when the comparison was physically different (“Miss” was also computed by averaging across the 20%, 40%, 60%, and 80% morph levels). “False Alarm” was responded as “different” when the…
