A gut feeling: how your brain (and your guts) affect your decisions – preliminary results

Risk-taking behavior and intertemporal choices are common sources of inconsistences in decision-making. Although both phenomena have high economic and societal impacts, little is
known about their underlying neurological processes. This knowledge is essential to understand its mechanisms and correlations. Since this remains an open question in economics and neuroscience, we explore such underlying mechanisms, aiming to clarify if these processes are correlated and how they are processed. Risk-taking behavior was chosen as our topic based on the positive correlation between a rich gut microbiota and risk-taking behavior with rodents (Chumney & Robinson, 2006). Considering the promising results presented by studies
replicating such experiments with humans (Dinan et al., 2013), we believe we can prove the influence of the gut-brain axis on risk-taking behavior. Moreover, based on the possible common neural mechanisms underlying risk and time preferences (Bechara & Damasio, 2005), we also investigate the gut-brain influence on intertemporal choices. To explore such neurological processes we manipulate the gut microbiota, employing our most innovative
contribution, which is the use of probiotics to investigate how the gut-brain axis is involved in decision-making. Our experiment uses a mixed design with two sessions (28 days gap), and
different economic games to elicit risk-taking behavior and intertemporal choice. The preliminary results indicate that risk-taking and intertemporal choices are only correlated in
specific scenarios. This correlation was present when participants faced risk-choices with low contrast between the options' expected values, and with intertemporal choices involving longer
intervals. The probiotics intervention did not affect participants' stress response or intertemporal choices. However, a decrease in risk-taking behavior was observed after probiotics administration, which suggests an effect of the microbiota-gut-brain axis on decision-making under risk.