Decades of research have long established that people's reasoning can be biased by their intuitions and deviate from logical norms. Popular dual process models that characterize thinking as an interaction between intuitive and deliberate thought processes have presented an appealing explanation for this observation. Within this account logical reasoning is traditionally considered as a prototypical example of a task that requires effortful deliberate thinking. In recent years, however, a number of findings obtained with new behavioral paradigms have questioned the traditional dual process characterization. A key observation is that people can process logical principles in classic reasoning tasks intuitively without deliberation.

The fast or intuitive logic findings have far stretching theoretical implications for dual process theories and our view of human rationality. However, the nature of this newly discovered fast logical reasoning is not clear. One limitation is that its neural basis has not been explored. The primary goal of this project is to address this shortcoming in a functional magnetic resonance imaging (fMRI) study. In the study adult participants will solve classic reasoning problems (i.e., variants of the bat-and-ball problem) in the scanner. Half of the trials will be traditional "Slow" trials in which participants get ample time to deliberate (i.e., 20 s). The other half of the trials will be "Fast" trials in which people do not get sufficient time to deliberate (i.e., 4 s deadline) and need to rely on intuitive processing.

All participants in the fMRI study will be healthy adults aged between 18-45. In addition to contrasting correct responders' brain activation during fast and slow trials, we will also contrast the fast and slow activations for correct and incorrect responses. This will allows us to identify brain regions associated with both correct and incorrect fast and slow logical responses and reach our study objective.

Inclusion Criteria:

• right-handed
• signed informed consent form
• medical, neurological, neuroradiological healthy
• social security number
• use of contraception for female subjects

Exclusion Criteria:

• standard contra-indication for MRI examination (pacemaker, metallic implants/dental braces, claustrophobia, pregnancy)
• chronic drug or alcohol user
• cognitive disorders linked to cardiovascular accidents
• chronic neurological or psychiatric disorder
• history of major illness (diabetes, metabolic, cancer, immunological)
• use of medicines that can potentially interfere with cerebral imaging (psychotropic drugs, hypnotics, anxiolytics, neuroleptics, anti-parkinson drugs, benzodiazepines, steroidal anti-inflammatory drugs, antiepileptics, anti-histamines, central analgesics and muscle relaxants)
• dyschromatopsia
• pregnant female
• non-MRI compatible tattoo

Healthy adults

We plan to share the anonymized study data (behavioral scores and imaging data) on the open-science framework. This will allow other researchers to verify or statistical analyses.