stronger reductions of P3 amplitudes for intonations spoken in high emotional intensity. This may suggest that individuals with difficulty identifying and verbalizing feelings generally ascribe less significance to emotional speech qualities, a process that may be particularly prominent in the case of disgusted prosody. Regarding the affective alexithymia dimension, this process might be even more pronounced for emotional prosody spoken with high intensity. A specific role for disgusted prosody. Though all prosodic emotions tested in the present study were affected by alexithymia, we observed some indications for a specific role of disgusted prosody. Individuals with difficulty identifying feelings as part of the cognitive alexithymia dimension exhibited overall delayed eMMN peak latencies for disgusted prosody, suggesting a delay in the unattended acoustic encoding of disgust conveyed by speech. Further, individuals with difficulty verbalizing feelings showed particularly reduced P3 amplitudes in response to the detection of disgusted prosodic deviants. Though no special role of disgust at the electrophysiological level was found in relation to the affective alexithymia dimension, both dimensions were associated with impaired identification of disgusted prosody at the behavioral level. These results may indicate a specific role of disgusted prosody during emotional speech processing in alexithymia. However, previous findings on facial emotion recognition do not seem to suggest a specific role of disgusted emotion, but indicate a more general deficit in emotion recognition associated with alexithymia [82,85,86]. As the auditory perception of disgust has not been investigated before in relation to alexithymia, it may be worthwhile to test the possibility of a specific deficit in the processing of disgusted prosody in future studies. Summary In summary, the present findings hint toward a dissociable impact of the cognitive and affective alexithymia dimensions on the processing of emotional speech qualities. These results provide further support to the notion that the two alexithymia dimensions may be differentially linked to emotional processing [9,10]. Based on the distinction between these two dimensions, the existence of two different subtypes of alexithymia has been proposed [8,87]. Individuals with type I alexithymia are thought to be characterized by a general lack of responsiveness to emotion at both the cognitive level and the level of emotional experience, whereas individuals with type II alexithymia experience feelings to a normal or even heightened degree, whereas their ability to cognitively regulate their feelings is impaired, possibly putting them at risk to develop psychopathological conditions characterized by affect dysregulation [10]. Future studies could attempt to differentiate between different alexithymia subtypes taking into account the affective alexithymia dimension in addition to its cognitive dimension, rather than considering alexithymia as a unitary construct. Such a differentiation would be beneficial to a better understanding of the neurophysiological basis of emotional References 1. Salminen JK, Saarija¨rvi S, A¨a¨rela¨ E, Toikka, T, Kauhanen, J (1999) Prevalence of alexithymia and its association with sociodemographic variables in the general population of Finland. Journal of Psychosomatic Research 46: 75–82. 2. Taylor GJ, Bagby RM, Parker JDA (1997) Disorders of Affect Regulation: Alexithymia in Medical and Psychiatric Illness. Cambridge: Cambridge University Press. 3. Berthoz S, Hill EL (2005) Reliability of the Bermond-Vorst Alexithymia Questionnaire: data from adults with autism spectrum disorder, their relatives and normal controls. European Journal of Psychiatry 20: 281–298. 4. Bird G, Silani G, Brindley R, White S, Frith U, et al. (2010) Empathic brain responses in insula are modulated by levels of alexithymia but not autism. Brain 133: 1515–1525. The Sound of Feelings processing deficits associated with this multifaceted personality construct. Limitations It should be kept in mind that the sample of the present study comprised only female participants, and that our results may therefore not be generalizable to male individuals with alexithy- mia. Also, mood states of participants were not assessed though alexithymia has been associated with reduced positive affect [88]. Further, the range of affective alexithymia scores in our sample was relatively small compared to the range of scores on the cognitive alexithymia dimension. Future studies should try to overcome these limitations by testing a sufficient number of female and male individuals with a broad range of scores on both the affective and the cognitive dimension of alexithymia. In addition, we used sad prosody as standards during attended processing in task 2 as we were interested in measuring changes between emotional intonations as they often occur in daily conversations instead of changes from a neutral to an emotional intonation. However, since neutral prosody served as standards during unattended processing in task 1, it should be noted that the results of the two tasks are not directly comparable. Future studies could attempt to keep paradigms and stimuli identical during unattended and attended processing if specific effects of attention on emotional prosody processing in relation to alexithymia are of interest. Conclusions In conclusion, alexithymia seems to modulate electrophysiolog- ical responses to emotional speech during attended as well as unattended processing. The two alexithymia dimensions appear to exert a dissociable impact on emotional prosody processing, with a left-hemisphere bias characteristic for the cognitive alexithymia dimension during early stages of unattended processing. The affective alexithymia dimension seems to influence the perception of emotional prosody at later processing stages than the cognitive dimension, and appears to be additionally sensitive to the intensity of emotional speech. These results suggest that alexithymia indeed affects the way emotional speech qualities are processed in the brain, which could be a contributing factor to problems in interpersonal communication associated with this personality construct. Acknowledgments We thank Michelle Servaas for her support in participant recruitment and EEG recordings, and Peter Albronda for technical support during the EEG sessions. Author Contributions Conceived and designed the experiments: KG AA SM. Performed the experiments: KG. Analyzed the data: KG AA SM. Contributed reagents/ materials/analysis tools: KG AA SM. Wrote the paper: KG. 5. Frith U (2004) Emanuel Miller lecture: confusions and controversies about Asperger syndrome. Journal of Child Psychology and Psychiatry 45:672– 686. 6. Hill EL, Berthoz S, Frith U (2004) Brief Report: cognitive processing of own emotions in individuals with autistic spectrum disorder and in their relatives. Journal of Autism and Developmental Disorders 34: 29–235. 7. Sifneos PE (1973) The prevalence of ‘alexithymic’ characteristics in psychoso- matic patients. Psychotherapy & Psychosomatics 22: 255–262. 8. Vorst HCM, Bermond B (2001) Validity and reliability of the Bermond-Vorst Alexithymia Questionnaire. Personality and Individual Differences 30: 413–434. 9. Bermond B, Bierman DJ, Cladder MA, Moormann P, Vorst HM (2010) The cognitive and affective alexithymia dimensions in the regulation of sympathetic responses. International Journal of Psychophysiology 75: 227–233. PLoS ONE | www.plosone.org 12 May 2012 | Volume 7 | Issue 5 | e36951