Tasting rewards. Effects of orosensory sweet signals on human error processing

ABSTRACT

Human research has shown interactions between rewards and cognitive control. In animal models of affective neuroscience, reward administration typically involves administering orosensory sugar signals (OSS) during caloric-deprived states. We adopted this procedure to investigate neurophysiological mechanisms of reward-cognitive control interactions in humans. We predicted that OSS would affect neurophysiological and behavioral indices of error processing oppositely, depending on the relative weight of the OSS-induced ‘wanting’ and ‘liking’ components of reward. We, therefore, conducted a double-blind, non-nutritive sweetener-controlled study with a within-subject design. Fasted (16 hr) participants (N = 61) performed a modified Flanker task to assess neurophysiological (error-related negativity [N_e/ERN]) and behavioral (post-error adaptations) measures of error processing. Non-contingent to task performance, we repeatedly administered either a sugar (glucose) or non-nutritive sweetener (aspartame) solution, which had to be expulsed after short oral stimulation to prevent post-oral effects. Consistent with our hypothesis on how ‘liking’ would affect N_e/ERN amplitude, we found the latter to be decreased for sugar compared to aspartame. Unexpectedly, we found post-error accuracy, instead of post-error slowing, to be reduced by sugar relative to aspartame. Our findings suggest that OSS may interact with error processing through the ‘liking’ component of rewards. Adopting our reward-induction procedure (i.e. administering OSS in a state of high reward sensitivity [i.e. fasting], non-contingent to task performance) might help future research investigating the neural underpinnings of reward-cognitive control interactions in humans.

KEYWORDS:

• Carbohydrate mouth rinsing
• reward
• 'liking'
• 'wanting'
• error negativity/error-related negativity (N_e/ERN)
• fasting
• sweet taste‌
• error processing
• performance monitoring

Acknowledgements

We gratefully thank all the following people and organizations for the support: all of the German Sport University interns (Lili Dubreuil, Marina Griesbach, Julia Pelzer, Geraldy Tokplen, and Lorenzo Fenu) for their help in carrying out the experiment, Markus Raab for providing the laboratory, Alice Heinrich for technical support, UD Chemie GmbH Wörrstadt for providing the aspartame free of charge, and Hans Braun for his inspiring teaching that motivated TJH to conduct this experiment. Finally, we would like to thank Kirsten Neumann and Matthew Watson for proofreading.

Author contributions

TJH, SH, and SL conceived and designed the study. TJH and NB carried out the data collection. TJH, AL, TJ, and MS performed the data analysis. TJH, TJ, and MS interpreted the data. TJH drafted the article. All authors revised the draft critically and approved the final version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by research funds from the German Sport University Cologne in the form of a grant awarded to TJH (grant no: 2017, Call No. 1, internal research funds).

Notes on contributors

Thomas J. Hosang

Thomas J. Hosang (MSc) is a PhD student in experimental and biological psychology in Professor Jacobsen’s research group. His research focuses on the the effects of sweet taste on human cognition.

Sylvain Laborde

PD Dr. Dr. Sylvain Laborde is a lecturer at the German SportUniversity Cologne (Institute of Psychology, Performance Psychology Department). His research focuses on heart rate variability as a selfregulation marker, and on emotional intelligence.

Michael Sprengel

Michael Sprengel (MSc) is a PhD student in experimental and biological psychology in Professor Jacobsen’s research group. M. Sprengel is currently focused on disentangling the mechanisms underlying adaptive behavior in exprimental conflict protocols.

Andreas Löw

Dr. Andreas Löw is Laboratory Manager at the Helmut-Schmidt-University. Dr. Löw’s research focuses on cognitive and affective neuroscience. He has extensive experience in psychophysiological methods and biosignal analysis.

Niels Baum

Niels Baum is a bachelor student at the German Sport University. During his bachelor, he specialized on the effect of sweet taste on human cognition.

Sven Hoffmann

Dr. Sven Hoffmann is senior researcher at the departments “Psychological Methods and Evaluation” and “General Psychology” at the University of Hagen. He is interested in the question: What is action? Using behavioral and psychophysiological measures (like EEG) he investigates what processes are involved in initiating, guiding, and evaluating the outcomes of action. Particularly errors and their cognitive processing play a crucial role in this regard. Also, he is interested in neuroscientific and statistical methods, in particular, multivariate statistics in psychophysiology (e.g. independent component analysis or machine learning).

Thomas Jacobsen

Prof. Dr. Thomas Jacobsen is a university professor of experimental and biological psychology. His research is on mental function, frequently taking a neuroscientific approach.