Creating Stimuli for the Natural Viewing Task (NVT)
Abstract
Introduction
Understanding the human brain has been a research focus for a century. In fMRI studies, that developed into task-based paradigms with highly structured stimuli and instructions to elicit one specific process [1]. In contrast, resting-state (RS) studies observe functional connectivity (FC) of unconstrained cognition with virtually no stimuli or instructions.
Both task and RS studies have offered us important new insights but face several drawbacks. Task stimuli cannot be found in daily life, so these paradigms face poor ecological validity, risk misunderstanding instructions etc., while RS often includes undesired microsleeps and due to the unconstrained nature of it, makes it hard to separate the signal from noise (e.g., motion) and makes it an unreliable baseline measure to task paradigms (e.g., [1, 2]), which limits the drawn inferences [2].
To curb the drawbacks, naturalistic paradigms have been gaining momentum. These include audio and/or visual narratives (e.g., videos or audiobooks) to which subjects attend as they would at home, for example. Among other improvements, their use does not depend on understanding instructions, increases ecological validity, and avoids active stimuli manipulation as well as unconstrained cognition. They have also been shown to successfully evoke several different cognitive processes, thereby offering a valuable complementary approach [3]. With the increasing use of this approach, there is a need for a set of stimuli that have been shown to reliably elicit specific cognition. Creating a set of such stimuli will be the focus of my thesis.
Methods
We will identify several target processes (e.g., emotion, motor, language) and prepare several audio-visual clips to elicit each target process (e.g., feeling of sadness). On separate samples of 20 healthy participants, we will use phenomenological interviews, a questionnaire (e.g., ReSQ) and fMRI to check how successfully processes were elicited across participants.
Expected Results
A set of clips that will most consistently elicit the target cognitive processes across participants will be chosen to constitute the NVT. NVT will be further validated in a following fMRI pilot study. This could offer an important contribution as an alternative to task and RS studies and aid the development and use of naturalistic paradigms.
References
[1] U. Hasson, ‘Intersubject Synchronization of Cortical Activity During Natural Vision’, Science, vol. 303, no. 5664, pp. 1634–1640, Mar. 2004, doi: 10.1126/science.1089506.
[2] S. Sonkusare, M. Breakspear, and C. Guo, ‘Naturalistic Stimuli in Neuroscience: Critically Acclaimed’, Trends Cogn. Sci., vol. 23, no. 8, pp. 699–714, Aug. 2019, doi: 10.1016/j.tics.2019.05.004.
[3] I. P. Jääskeläinen, M. Sams, E. Glerean, and J. Ahveninen, ‘Movies and narratives as naturalistic stimuli in neuroimaging’, NeuroImage, vol. 224, p. 117445, Jan. 2021, doi: 10/gh5j47.
