Comparison of Slides and Video Clips as Different Methods for Inducing Emotions: An Electroencephalographic Alpha Modulation Study

Abstract

Films, compared with emotional static pictures, represent true-to-life dynamic stimuli that are both ecological and effective in inducing an emotional response given the involvement of multimodal stimulation (i.e., visual and auditory systems). We hypothesized that a direct comparison between the two methods would have shown greater efficacy of movies, compared to standardized slides, in eliciting emotions at both subjective and neurophysiological levels. To this end, we compared these two methods of emotional stimulation in a group of 40 young adults (20 females). Electroencephalographic (EEG) Alpha rhythm (8–12 Hz) was recorded from 64 scalp sites while participants watched (in counterbalanced order across participants) two separate blocks of 45 slides and 45 clips. Each block included three groups of 15 validated stimuli classified as Erotic, Neutral and Fear content. Greater self-perceived arousal was found after the presentation of Fear and Erotic video clips compared with the same slide categories. sLORETA analysis showed a different lateralization pattern: slides induced decreased Alpha power (greater activation) in the left secondary visual area (Brodmann Area, BA, 18) to Erotic and Fear compared with the Neutral stimuli. Instead, video clips elicited reduced Alpha in the homologous right secondary visual area (BA 18) again to both Erotic and Fear contents compared with Neutral ones. Comparison of emotional stimuli showed smaller Alpha power to Erotic than to Fear stimuli in the left precuneus/posterior cingulate cortex (BA 7/31) for the slide condition, and in the left superior parietal lobule (BA 7) for the clip condition. This result matched the parallel analysis of the overlapped Mu rhythm (corresponding to the upper Alpha band) and can be interpreted as Mu/Alpha EEG suppression elicited by greater motor action tendency to Erotic (approach motivation) compared to Fear (withdrawal motivation) stimuli. Correlation analysis found lower Alpha in the left middle temporal gyrus (BA 21) associated with greater pleasantness to Erotic slides (r38 = –0.62, p = 0.009), whereas lower Alpha in the right supramarginal/angular gyrus (BA 40/39) was associated with greater pleasantness to Neutral clips (r38 = –0.69, p = 0.012). Results point to stronger emotion elicitation of movies vs. slides, but also to a specific involvement of the two hemispheres during emotional processing of slides vs. video clips, with a shift from the left to the right associative visual areas.

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

“…A similar pattern of findings was also observed in previous research using dynamic stimuli (film clips, or looming stimuli), in which it was reported that emotional stimuli trigger a greater alpha sustained decrease compared to neutral stimuli (Kim et al, 2021; Romeo et al, 2022; Sarlo et al, 2005; Vagnoni et al, 2015). The impact of unpleasant film clips on oscillatory activity was investigated by Sarlo et al (2005) who wanted to clarify the specificity of alpha changes induced by different unpleasant contents.…”

“…Consistently, this pattern of ERD findings has been observed not only with pictures but also with other emotional reactivity induction techniques, such as film clips (Romeo et al, 2022). Romeo et al (2022) reported a larger alpha ERD for erotic and fear-inducing film clips compared to neutral ones, and, in addition, a larger alpha ERD for erotic compared to fear-inducing film clips over posterior regions. Although picture repetition does not affect the alpha ERD for either pleasant or unpleasant stimuli, an enhanced alpha ERD has been observed when novel emotional stimuli (pleasant and unpleasant), but not neutral ones, are presented after an extensive phase of stimulus repetition.…”

“…Most studies failed to find a difference between pleasant and unpleasant contents (Cui et al, 2013; De Cesarei & Codispoti, 2011; Messerotti Benvenuti et al, 2019; Murphy et al, 2020; Wang et al, 2021), while in two studies erotica elicited a larger alpha ERD than mutilation/injury (Ferrari et al, 2020, 2022). Consistently, this pattern of ERD findings has been observed not only with pictures but also with other emotional reactivity induction techniques, such as film clips (Romeo et al, 2022). Romeo et al (2022) reported a larger alpha ERD for erotic and fear‐inducing film clips compared to neutral ones, and, in addition, a larger alpha ERD for erotic compared to fear‐inducing film clips over posterior regions.…”

Gender effect in affective processing: Alpha EEG source analysis on emotional slides and film‐clips

“…The differences emerged in the last decades of research (e.g., engagement of left versus right regions; contribution of different EEG rhythms) may depend on the kind of stimuli used for inducing emotional reactions (e.g., pictures, faces, clips). Notably, the presentation of static pictures and dynamic clips elicited different EEG patterns of activation in the same group of participants (Romeo et al., 2022). Moreover, ecological and multimodal materials (e.g., movie clips) are more effective in prompting subjective and physiological emotional responses compared to images (Gross & Levenson, 1995; Palomba et al., 2000; Rottenberg et al., 2007; Schaefer et al., 2010).…”

“…Source localization was computed by means of sLORETA, the most widely used approach in the field because of its accuracy and speed of computation (Asadzadeh et al., 2020; Pascual‐Marqui, 2002). sLORETA is also widely used in emotional research (Ertl et al., 2013; Maffei et al., 2019; Romeo et al., 2022; Romeo & Spironelli, 2023).…”