This is a registered report aimed at assessing the role of the vestibular system in the attribution of value to positive and negative reinforcers, and consequent modulations of conflict costs caused by (valuable) distractors. TIMELINE OF EVENTS 2020, October 2: the paper has been accepted and it is now published on Cortex as a registered report. DOI: https://doi.org/10.1016/j.cortex.2020.09.004 2020, September 3: we received peer reviews from Cortex on July 31. We revised the manuscript accordingly, re-submitted the paper to the journal, and updated the pre-print posted on BiorXiv. 2020, May 23: The preprint for this project is available on biorxiv (https://www.biorxiv.org/content/10.1101/2020.05.17.100255v1). The paper has been submitted to Cortex as stage 2 registered report. 2020, May 14: all the scripts for both pre-registered and exploratory analyses have been uploaded. Scripts come in the form of html files, which are handy because they can be clearly annotated and all the produced plots are embedded in the files. A pre-print summarising the analyses and results will be produced shortly. 2019, October 28th: the laboratory log has been uploaded. This is the official file sent to the promotor of the study (the hospitals of Lyon) in accordance with the ethics protocol and French laws. Please note that the the first 32 subjects in the log refer to a previous study (Cortex, 2018), as it was approved on the same protocol. Recruitment for the current study starts from subject 33 and ends at subject 74 (42 participants overall). The file reports the inclusion date (medical screening plus informed consent signature) and that of the last experimental session. 2019, September 18th: the last participant has been tested (N= 42 total). All raw data files have been uploaded (September 19th). 2019, May 22th: The first participant (first session) has been tested - medical screening done on May, the 13th. 2019, May 7th: we received In Principle Acceptance from the journal Cortex, thus the study now officially begins. 2019, March 20th: we received peer-review from the journal Cortex. We have thus amended the manuscript and experimental tasks as a consequence (Stage 1, version 2). The most substantial revision concerned the introduction and its structure. We have made more explicit the mechanistic model that was driving our predictions, and we have downplayed the reference to addiction disorders. We have also better justified several methodological choices. 2018, December 10th: the first version, not peer-reviewed, of the stage 1 protocol has been uploaded. The scripts for running the tasks have been uploaded (they require the free program OpenSesame). The script for the power analysis has been uploaded.