Comparing Neural Correlates of Human Emotions across Multiple Stimulus Presentation Paradigms

Abstract

Most electroencephalography (EEG)-based emotion recognition systems rely on a single stimulus to evoke emotions. These systems make use of videos, sounds, and images as stimuli. Few studies have been found for self-induced emotions. The question “if different stimulus presentation paradigms for same emotion, produce any subject and stimulus independent neural correlates” remains unanswered. Furthermore, we found that there are publicly available datasets that are used in a large number of studies targeting EEG-based human emotional state recognition. Since one of the major concerns and contributions of this work is towards classifying emotions while subjects experience different stimulus-presentation paradigms, we need to perform new experiments. This paper presents a novel experimental study that recorded EEG data for three different human emotional states evoked with four different stimuli presentation paradigms. Fear, neutral, and joy have been considered as three emotional states. In this work, features were extracted with common spatial pattern (CSP) from recorded EEG data and classified through linear discriminant analysis (LDA). The considered emotion-evoking paradigms included emotional imagery, pictures, sounds, and audio–video movie clips. Experiments were conducted with twenty-five participants. Classification performance in different paradigms was evaluated, considering different spectral bands. With a few exceptions, all paradigms showed the best emotion recognition for higher frequency spectral ranges. Interestingly, joy emotions were classified more strongly as compared to fear. The average neural patterns for fear vs. joy emotional states are presented with topographical maps based on spatial filters obtained with CSP for averaged band power changes for all four paradigms. With respect to the spectral bands, beta and alpha oscillation responses produced the highest number of significant results for the paradigms under consideration. With respect to brain region, the frontal lobe produced the most significant results irrespective of paradigms and spectral bands. The temporal site also played an effective role in generating statistically significant findings. To the best of our knowledge, no study has been conducted for EEG emotion recognition while considering four different stimuli paradigms. This work provides a good contribution towards designing EEG-based system for human emotion recognition that could work effectively in different real-time scenarios.

Small Urban Green Spaces: Insights into Perception, Preference, and Psychological Well-being in a Densely Populated Areas of Tehran, Iran

“…The gamma band exhibited the highest classification performance, indicating its crucial role in capturing information related to emotion processing. 96 This finding is consistent with previous research that has associated gamma oscillations with visual cognition, emotion, attention, and memory. 97 , 98 The higher classification accuracy of the gamma band suggests its sensitivity to emotional stimuli and its potential as a neural marker of emotional states.…”

“…The identification of the gamma band as a robust neural marker of emotion processing in green spaces opens up avenues for further investigation. 96 Future studies could explore the specific cognitive and affective processes associated with gamma oscillations during exposure to green spaces. Additionally, the role of other frequency bands, such as alpha and theta, in emotional experiences within green environments could be investigated to gain a more comprehensive understanding of the neural mechanisms at play.…”

Alpha‐band oscillations and emotion: A review of studies on picture perception

“…Alpha band activity has long been examined in psychophysiological research in the context of the orienting response to visual and acoustic stimuli (e.g., geometric figures and tones); however, oscillatory activity during emotional processing has been less widely investigated. Previous literature reviews assessing EEG oscillatory activity during picture perception focused on a small number of studies showing inconsistent findings, and concluded that the emotional effects on alpha band activity were unclear (Güntekin et al, 2017; Güntekin & Başar, 2014; Masood & Farooq, 2021). Recently, systematic research has been conducted, and the studies reviewed here indicate that alpha desynchronization (ERD) over posterior sensors is reliably enhanced when viewing emotional compared with neutral pictures.…”

“…This phenomenon is called "Negative bias" and appears to be pervasive, as evidence has been found in a number of domains (Baumeister et al, 2001;Hilgard et al, 2014). While no conclusive evidence was reported in previous reviews of alpha activity (Başar & Güntekin, 2012;Güntekin & Başar, 2014;Masood & Farooq, 2021), a large and consistent body of evidence has demonstrated that emotional engagement modulates both cortical and autonomic responses, and this modulation is primarily driven by motivational intensity (or arousal) induced by visual stimuli, regardless of hedonic content (i.e., similar reactivity for unpleasant and pleasant, compared with neutral, stimuli; Adolphs & Anderson, 2018;Bradley et al, 2001Bradley et al, , 2012Codispoti & De Cesarei, 2007;Keil et al, 2008;Sabatinelli et al, 2005;Schupp et al, 2006;Zald, 2003). Therefore, one focus of the present review will be the valence-specificity of alpha emotional modulation, i.e., whether alpha activity is modulated only by unpleasant stimuli or also by those that are pleasant and whether the modulation is more pronounced for unpleasant, compared with pleasant, stimuli.…”

“…In a previous literature review assessing EEG oscillatory activity during emotional visual perception, Güntekin and Başar concluded that the effects of emotional processing on alpha band activity were unclear and inconsistent (Başar & Güntekin, 2012; Güntekin & Başar, 2014; Güntekin et al, 2017; see also Bekkedal et al, 2011; Knyazev, 2007; Masood & Farooq, 2021). However, despite many studies on alpha activity being available, they were not included in the reviews mentioned above.…”