Abstract:

The automatic detection of facial emotion changes is crucial for survival. Numerous studies using the event-related potential (ERP) technique have found that the amplitude of emotion-related visual mismatch negativity (EMMN) could be used to test the automatic processing of facial emotion. Previous studies suggested that deviant - standard stimulus (D-S) pair (different/same) and emotion type (negative/non- negative) might modulate the EMMN effect, however, the evidence so far was mixed. Therefore, we conducted a meta-analysis to analyze the findings of 35 studies (involving 721 healthy participants) on EMMN, among them, 26 (K = 43), 30 (K = 50), 22 (K = 24), and 24 (K = 26) studies (Kis the number of effect sizes) were used to analyze early EMMN effect, late EMMN effect, the negative bias of early EMMN effect and EMMN effect.

Results showed that: (1) EMMN effects emerged at both the early- (0~200 ms) and late- (200~400 ms) stages, demonstrating that infrequently presented deviant stimulus elicited more negative ERPs at both the early- and late-stages(early: g = -0.66, 95% CI: [-0.77 -0.56]; late:g= -0.61, 95% CI: [-0.76 -0.47]). This suggests that EMMN reflects the probability effect of early- and late- stages emotion-related ERP components; (2) the type of D-S pair moderated the EMMN effect at the early-(Q(1) = 8.58, p < 0.01) but not the late-stages( Q(1) = 2.92, p = 0.09). Specifically, the EMMN effect of different D-S pairs(g = -0.83, 95% CI: [-0.98 -0.68]) was significantly larger than that of the same D-S pairs(g = -0.52, 95% CI: [-0.66 -0.37]) at the early-stage; (3) in the studies of same D-S pairs, the evidence between equiprobable and non-equiprobable paradigm showed no significant differences in EMMN at both stages(early:Q(1) = 1.29, p = 0.26; late: Q(1) = 0.79, p = 0.38); (4) a negative bias was found in both early(g = -0.28, 95% CI: [-0.48 -0.09]) and late EMMN(g = -0.32, 95% CI: [-0.54 -0.10]), i.e., the EMMN elicited by the angry, fearful, angry faces was significantly larger than that of happy faces.

These results indicate that the EMMN effect is affected by experimental manipulations such as D-S pair type and emotion type. The influence of D-S pair type on the EMMN effect indicated that a low level of physical information would affect the early EMMN effect, which suggested that we should avoid using the traditional oddball paradigm to study the EMMN effect; In the study of the same D-S pair, the probability difference of D-S pair did not affect the EMMN effect, which indicated that visual refractoriness did not affect the EMMN effect. This suggests that it is feasible to study the EMMN effect by using the reverse oddball paradigm and the equiprobable paradigm. However, more evidence is needed for this conclusion, as the number of studies with the equiprobable(2) is far less than that of non-equiprobable(11). In addition, the EMMN effect is sensitive to emotion type, which negative emotion induces a greater EMMN effect. These results indicate that the EMMN is a crucial electrophysiological index for automatic facial emotion processing.

Key words: emotion-related visual mismatch negativity (EMMN), meta-analysis, negative bias, deviant- standard stimulus pair