Health communication and risk perception : A neuroscientific perspective

   Risk perception is a fundamental variable in models on health behavior change. Based on the assumption that personal risk perception influences behavior change, the dissertation aims to capture mechanisms underlying the perception of health-related risks. Furthermore, the potential of neural measures to assess health communication is examined. In two streams of research, personal risk perception is studied using two common risk behaviors: sexually transmitted infections (STI) and risky alcohol use.

   The first part of the dissertation targets mechanisms underlying intuitive social risk perceptions in two studies. Previous work on visually presented social information showed that STI risk perceptions about a person are made fast, effortless, and related to affect. Accordingly, intuitive processes have been ascribed a key role for social risk perception.
   One study used event-related potentials (ERP) and a simulated online dating platform to study the perception of multi-modal risk information. The main finding was an interaction of verbal and visual information, seen over anterior-temporal sensors between 270 to 430 ms - indicative of the integration of risk information early in the processing stream. This effect was driven by persons revealing both high verbal and high visual risk. Previous studies related ERP differences in response to persons perceived as risky to affective significance and enhanced attention. Hence, the findings are interpreted as a tagging of high-risk information serving as an alarm function.
   A second study had the aim to identify potential stereotypes underlying these social risk perceptions. The main result was that people seem to use a systematic set of cues when asked to evaluate HIV risk and trustworthiness based on person pictures. Furthermore, the cues were used to predict ratings of riskiness and trustworthiness in a new set of pictures.
Overall, the findings of these two studies corroborate the notion of intuitive influences in health-related social risk perceptions. Moreover, the findings support that stereotypical impressions of HIV risk are related to perceived trustworthiness.

   From an applied perspective, it is highly relevant to reveal how risk perception is effectively influenced to reach behavior change. Mass-media messages are a crucial strategy to promote public health. Media influences on risk perception, however, do not show simple sender-receiver relations, and many questions remain about how messages affect recipients. Thus, the second part expands the focus to real-life risk communication within three further studies. Short videos are commonly used in health communication. This requires an analysis approach for functional neuroimaging data (fMRI) that can handle complex naturalistic stimuli. Thus, the inter-subject correlation (ISC) analysis was used to elucidate how real-life risk communication unfolds its effects among recipients.
   A first study was focused on the properties of fMRI-ISC in use with short video segments. The findings indicated that fMRI-ISC offers a reliable measure of response similarities in use with short videos. The study revealed a gradient of ISC from primary-sensory to integrative, post-sensory regions related to psychological processes, such as saliency or personal relevance. Taken together, the findings suggest the ISC approach as a tool to assess dynamic processes underlying the perception of real-life risk information.
   In a second study, fMRI was used to examine how young adults “tune in” to real-life videos about risky alcohol use. The main finding of the study was that strong videos, evaluated to be more effective, commanded enhanced ISC. The enhancement was seen in cortical midline regions and the insula, which have previously been related to narrative engagement, self-relevance, and attention towards salient stimuli. The findings suggest that strong video health messages have greater “neural reach” across the brains of an audience.
   The third study expanded the approach to EEG to elucidate the processing of risk communication with a high temporal resolution, and in a further, independent target group. The EEG results revealed consistent ISC differences between strong and weak messages. In an additional stream of analysis, EEG-ISC was connected with fMRI data to identify sources of the spatially distinct correlated components. EEG-ISC co-varied over time with fMRI signal captured in another audience. Specifically, distinct correlated EEG components were related to higher-order, post-perceptual brain regions, such as the insula, the precuneus, the posterior and anterior cingulate and the medial prefrontal cortex. Finally, the potential of EEG-ISC to predict behavior change was explored and revealed relations between ISC and drinking at follow-up for components related to higher-order brain regions. The extension to EEG has translational potential as it provides a more accessible measure to quantify the impact of health messages within the brains of a target audience.
The findings of the three studies suggest that strong messages lead to enhanced engagement of the audience, reflected within more reliably shared brain responses. This engagement is found across two neuroscientific measures and is presumably related to psychological variables, such as saliency or personal relevance. The ISC approach thus offers a promising strategy for tracking the “neural reach” of health communication in target groups.

   Overall, the dissertation takes a perspective influenced by health psychology, communication science, and affective neuroscience. A neuroscientific perspective allows a systematic study of how risk information is processed, of what constitutes compelling risk information, and within which group of receivers the information is effective. This perspective presents a promising approach to a better understanding of message reception and behavior change. A better understanding of these mechanisms can improve strategies for communicating health risks and, ultimately – lead to healthier behavior.