|Author(s)||Krummenacher P. (1), Brugger P. (1), Fathi M. (2) & Mohr C. (3)|
|Addresse(s)||(1) Department of Neurology, University Hospital Zurich, Switzerland; (2) Clinical Chemistry Central Lab., University Hospital Geneva, Switzerland; (3) Department of Neurorehabilitation, University Hospital Geneva, Switzerland|
|Title||Dopamine, paranormal ideation, and the detection of meaningful stimuli.|
|Text||Dopamine (DA) is suggested to improve perceptual-cognitive decisions by increasing the signal-to-noise ratio. Somewhat paradoxically, hyperdopaminergia has also been implied in the genesis of unusual experiences like hallucinations and paranormal thought. To explore these assumptions, we used two lateralized decision tasks, one with lexical (tapping left hemisphere functions), the other with facial stimuli (tapping right hemisphere functions). Subjects were 40 healthy right-handed men, of whom 20 reported unusual, 'paranormal'experiences and beliefs ('believers'), while the remaining subjects were unexperienced and critical ('sceptics'). Levodopa (200mg) or placebo administration was balanced between belief groups (double-blind procedure, oral administration). We calculated sensitivity (d-prime) and response criterion (C) values, as introduced by signal detection theory, for each task and visual field, respectively. Our findings showed a typical right visual field advantage for the lexical decision task and a higher d-prime for verbal than facial stimulus material. Levodopa decreased subjects'd-prime, an effect that was, however, confined to the sceptics. Criterion analyses revealed that believers favoured false alarms over misses while sceptics displayed the opposite preference. Unexpectedly, levodopa reduced these decision preferences in both groups. We thus showed that levodopa 1) decreases sensitivity in perceptual-cognitive decisions, but only in sceptics, and 2) makes sceptics less and believers slightly more conservative. These results stand at odd to the common view that DA generally improves signal-to-noise ratios. Paranormal ideation is an important personality dimension that should never be left unassessed in tasks that investigate the detection of signals in noise.
|Theme||Cognition and behaviour
Human cognition and behaviour / Other higher functions