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Results from the present ERP study suggested that Schirmer and Kotz’s (2006) hierarchical model of prosody processing may also extend to emotional non-verbal vocalisations. However, the distinct emotion processing stages seem to be occurring earlier for vocalisations compared to prosody which may be due to prototypical representation of emotions in vocalisations. Further, the present study did not find pre-emotional stages of sensory processing, which suggest very rapid and automatic processing of emotional vocalisations.

In order to increase statistical significance in the present ERP study, it is necessary to increase the number of participants. Further, the current data may have contained some low levels of noise as it was conducted during hot summer days and sweat may influence electrical skin conductance and consequently decrease statistical power (Kappenman & Luck, 2010). Additionally, it was not possible to relate brain activity to behavioural findings due to a technical error. Hence, it is not known whether the ERP signal corresponds to accuracy rates of emotion categorisation across modalities. Further, the current ERP study was conducted with male participants only; hence, the results can neither be generalised across gender now can it explore potential gender differences during emotion recognition in voices and faces. However, since the behavioural chapters in this thesis did not find any main effects of gender, this was not the main focus of this ERP study.

Possible implications may arise from the current study: If applied to the real world, it is possible that voices communicate emotional intend earlier than face expressions. In an evolutionary context, it is possible that recognising emotional voices rather than emotional faces is important for threat avoidance in situations where vision is limited such as in darkness. This reflects verbal

feedback from participants after the ERP study who found the voices as ‘more exciting’ than the faces which in turn possibly motivated attention and emotion processing.

5.4.5. Conclusion

In conclusion, the present ERP study investigated in a within-subject design how similar emotion processes across two separate modalities are. Whilst the current data did not suggest significant emotion categorisation effects across any of the three time-windows for faces, voices showed distinct and hierarchical stages of processing with early discrimination of emotional versus neutral vocalisations and subsequent discrimination of angry versus happy vocalisations.

194 In terms of modality similarities, the current study could not confirm equal emotion-processing stages across faces and voices. However, there were also some similarities – at least to a degree - between emotion processing across faces and voices: for example, during the structural face and voice- decoding response such as the N170 and FTPV at around 150-170ms, neither of the modalities showed waveforms that were influenced by the emotionality of stimuli.

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General Discussion & Conclusions

How do we recognise emotions from individual modalities such as faces or voices? The aim of the present thesis was to investigate the above question in a multi-method manner and to

investigate how this ability develops with age and how it varies depending on cultural factors. Implementing a within-subject design to rate emotions across modalities counteracts the many different measures and stimuli previously used in emotion recognition research which make comparisons of results difficult (Bayer & Schacht, 2014). For the present investigation, cognitive, developmental, longitudinal, cross-cultural and neuroimaging studies as well as an online-survey were conducted in order to investigate from several viewpoints whether emotion recognition was

comparable across faces and voices.

Chapter 2 suggested that emotions presented in one modality can be recognised in comparable manner with emotions presented in a second, separate modality. Consequently, there is a possibility that emotions are categorised more on the appraisal of the events itself (Scherer, 1984) rather than on perceptual features such as the typical smile in happy faces (Ekman & Friesen, 2003). It has been hypothesised that there may be one general emotion core network which acts independently of modality (Peelen et al., 2010) and the current behavioural data supports this statement.

Chapter 3 suggested that this modality-independent emotion processing may be a feature of development because as age increased, recognition across modalities became more similar. Across both modalities, emotion recognition improved with age. Findings from the child Chapter 3 additionally validated the newly developed child face database DDCF (Dalrymple, Gomez, & Duchaine, 2013) for the use in children which has not been tested before. The present longitudinal study indicated, however, that emotion processing development in faces may happen in stages which cover periods longer than 1.5 years before changes are visible. Overall, children’s facial emotion recognition was not influenced by in-group age effects.

The originality of the current investigation into emotion recognition has further been demonstrated by comparing German and British individuals in their emotion recognition. Chapter 4, showed universal signs of basic emotion recognition which were coloured by subtle differences depending on culture, in line with the Dialect theory (Elfenbein & Ambady, 2003). It is possible that underlying differences in display rules such as the German reservedness (e.g. Wouters, 2011) may be linked to dampened intensity perception in the German compared to the British sample.

196 Children on the other hand showed less vulnerability to culture effects during emotion recognition; hence, it is possible that whilst general developmental aspects drive emotion recognition during childhood, only in adulthood does culture drive emotion recognition.

Lastly, the present ERP Chapter 5 aimed to investigate neurophysiological features of emotion processing across two separate modalities. Hierarchical emotion processing stages were found on the voice condition with emotion processing visible as early as 100ms after stimulus onset. However, no emotion effects were visible for the face condition. Overall, the results of the current ERP study remain preliminary and further testing needs to be conducted with a larger sample size.