ERP data: Attended processing of emotional prosody Figure 3 (right panel) shows the N1, P2, and P3 elicited by deviants in emotional prosody (happy, angry, and disgusted deviants averaged) versus sad standards during attended proces- sing in task 2 (grand average across all subjects at the parietal electrode site Pz). All main effects and interactions for amplitudes and latencies of the N1, P2, and P3 are summarized in table 1 (affective alexithymia dimension) and table 2 (cognitive alexithy- mia dimension). N1. For the cognitive dimension, a significant interaction cognitive dimension 6region [F(2,114) = 4.335, p = .037] was found for peak amplitudes of the N1, suggesting larger N1 amplitudes at centroparietal regions with increasing scores on the cognitive alexithymia dimension. Follow up tests on each cognitive subscale revealed that this interaction was driven only by difficulty analyzing feelings [F(2,114) = 4.677, p = .030]. Peak latencies of the N1 showed no difference as a function of the cognitive alexithymia dimension. The affective dimension was not associated with differences in N1 amplitude or latency. P2. For the cognitive dimension, RM-MANCOVA on P2 peak amplitudes revealed a significant interaction cognitive dimension 6 region [F(2,114) = 4.128, p = .037]. Follow up tests showed that this interaction was driven only by the subscale difficulty analyzing feelings, which was associated with reduced frontal P2 amplitudes. For the affective dimension, there was also a significant interaction affective dimension 6 region [F(2,114) = 6.836, p = .006]. Follow up tests revealed that this interaction was driven by the The Sound of Feelings fantasizing subscale [F(2,114) = 6.077, p = .010], which was found to be associated with reduced frontal P2 amplitudes (Figure 4, left). Peak latency of the P2 did not vary as a function of either alexithymia dimension. P3. For the cognitive dimension, RM-MANCOVA showed a significant interaction cognitive dimension 6 region [F(2,112) = 9.125, p = .003], suggesting reduced amplitudes of the P3 at parietal regions with increasing scores on the cognitive alexithymia dimension. Follow up tests on each subscale revealed that this interaction was driven by difficulty verbalizing feelings [F(2,112) = 12.544, p,.001] and difficulty identifying feelings [F(2,112) = 5.711, p = .017], which were both associated with reduced P3 amplitudes at parietal regions. In addition, the verbalizing subscale showed a significant three-way interaction verbalizing 6 emotion 6 region [F(4,224) = 3.087, p = .046]. Follow up tests on each emotion revealed a significant interaction verbalizing 6 region [F(2,112) = 7.946, p = .001] for disgusted prosody, indicating that difficulty verbalizing feelings was associated with reduced parietal P3 amplitudes particularly during the detection of disgusted prosodic deviants (Figure 4, right). For the affective dimension, RM-MANCOVA showed a signif- icant affective dimension 6 intensity interaction [F(1,56) = 5.792, p = .019], which was further qualified by the factor region [affective dimension 6 intensity 6 region: F(2,112) = 4.093, p = .046]. Follow up tests on each affective subscale revealed significant effects of both the emotionalizing and the fantasizing subscale: For the emotionalizing subscale, there was a significant interaction emotionalizing 6 intensity [F(1,56) = 6.433, p = .014], suggesting that the reduction in P3 Table 2. Statistical results of the RM-MANCOVA including the cognitive alexithymia dimension as a covariate. Main effects and interactions Post hoc tests EMMN Amplitude Latency LMMN Amplitude Latency N1 Amplitude Latency P2 Amplitude Latency P3 Amplitude Latency Region F (4,216) = 8.327, p = .002 Laterality 6 Region F (8,432) = 4.554, p = .002 Laterality F (2,108) = 4.616, p = .012 Region F (4,216) = 6.341, p = .003 Laterality 6 Cognitive Dimension F (2,108) = 4.160, p = .018 Laterality 6 Region F (8,432) = 3.696, p = .007 Emotion F (3,162) = 4.775, p = .003 Laterality F (2,108) = 4.338, p = .015 No significant effects Region F (2,114) = 17.738, p,.001 Laterality 6 Cognitive Dimension F (2,114) = 4.128, p = .037 Laterality F (2,114) = 8.897, p,.001 Region F (2,114) = 4.304, p = .037 Region 6 Cognitive Dimension F (2,114) = 4.335, p = .037 Emotion F (2,112) = 3.378, p = .038 Laterality F (2,112) = 8.013, p = .001 Region F (2,112) = 21.881, p,.001 Region 6 Cognitive Dimension F (2,112) = 9.125, p = .003 Region F (2,112) = 14.277, p,.001 Earlier left-hemispheric and trend toward delayed right- hemispheric eMMN peak amplitude (p,.1) with increasing scores on the cognitive alexithymia dimension (verbalizing and identifying subscales) Enhanced N1 peak amplitudes at centroparietal regions with increasing scores on the cognitive alexithymia dimension (analyzing subscale) Reduced P2 peak amplitudes at frontal regions with increasing scores on the cognitive alexithymia dimension (analyzing subscale) Reduced P3 peak amplitudes at parietal regions with increasing scores on the cognitive alexithymia dimension (verbalizing and identifying subscale) Post hoc tests are significant at p,.05 (Sidak-corrected) unless otherwise specified. doi:10.1371/journal.pone.0036951.t002 PLoS ONE | www.plosone.org 9 May 2012 | Volume 7 | Issue 5 | e36951