LAUSR

Editor – this is a response to the comment by Watsjold and Coltheart: Evident absence, absent evidence: a comment on Rotgans et al. (2018). In our experiment, we trained medical students to pattern-recognise chest X-rays. Once they had reached high levels of expertise in correctly diagnosing these chest X-rays they proceeded to a test phase. During the test phase, sets of trained and sets of untrained chest X-rays were presented. We were able to demonstrate that, in this withingroup experiment, our students behaved in ways predicted by the cognitive dual-process theory: trained cases led to two times faster processing and three times fewer diagnostic mistakes. More importantly, we were able to show, using neuroimaging, that only when confronted with untrained cases significant prefrontal cortex activity emerged amongst our participants in the form of higher concentrations of oxyhaemoglobin in the prefrontal cortex. No such activity was seen for the trained cases. We construed these findings as neuroscientific evidence supporting dual-process theory: if analytical reasoning is associated with higher concentrations of oxyhaemoglobin in the prefrontal cortex, and if such activity is not seen under recognition conditions, then in the latter case processing must take place elsewhere.