Naturalistic Stimuli in Affective Neuroimaging: A Review.

Heini Saarimäki

doi:10.3389/fnhum.2021.675068

Abstract

Naturalistic stimuli such as movies, music, and spoken and written stories elicit strong emotions and allow brain imaging of emotions in close-to-real-life conditions. Emotions are multi-component phenomena: relevant stimuli lead to automatic changes in multiple functional components including perception, physiology, behavior, and conscious experiences. Brain activity during naturalistic stimuli reflects all these changes, suggesting that parsing emotion-related processing during such complex stimulation is not a straightforward task. Here, I review affective neuroimaging studies that have employed naturalistic stimuli to study emotional processing, focusing especially on experienced emotions. I argue that to investigate emotions with naturalistic stimuli, we need to define and extract emotion features from both the stimulus and the observer.

Highlights

A touching movie, a horror story, or a vivid discussion all evoke strong emotions
What are the neural dynamics of emotional processing in such natural conditions? Affective neuroimaging has traditionally used simple, controlled paradigms, that rely on varying one aspect of a stimulus at the time and often use short, prototypical emotion stimuli such as static images, movie clips, or facial expressions
Emotions are generally defined as momentary processes caused by internal or external stimuli and leading to automatic changes in multiple functional components, including physiology, behavior, motivation, and conscious experiences (e.g., Barrett et al, 2007; Scherer, 2009; LeDoux, 2012; Anderson and Adolphs, 2014)

Summary

INTRODUCTION

A touching movie, a horror story, or a vivid discussion all evoke strong emotions. What are the neural dynamics of emotional processing in such natural conditions? Affective neuroimaging has traditionally used simple, controlled paradigms, that rely on varying one aspect of a stimulus at the time and often use short, prototypical emotion stimuli such as static images, movie clips, or facial expressions. While the controlled paradigms are powerful in investigating the neural processes underlying a specific emotional component, such as the recognition of facial expressions, they lack the complicated dynamics of real-life emotional encounters Naturalistic stimuli such as longer movies and stories have emerged as a possibility to merge ecologically valid stimuli and FIGURE 1 | A framework for extracting emotion features in naturalistic paradigms. Naturalistic stimuli allow investigating multiple functional components simultaneously, modeling emotion dynamics at different timescales, and studying individual variation. Emotional processing includes activating widespread functional components within the observer, such as those corresponding to bodily changes and motor planning, which are not directly related to the incoming stimulus but affect the resulting emotional experience (Damasio and Carvalho, 2013; Barrett, 2017; Nummenmaa and Saarimäki, 2019).

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CONCLUSION