Forstmann, B. U.
Cognitive Science Center Amsterdam, University of Amsterdam, the Netherlands
For many everyday life decisions, people face the dilemma that fast decisions tend to be error-prone, whereas accurate decisions tend to be relatively slow. In other words, people can choose to respond more quickly at the cost of making more errors, a phenomenon known as the speed-accuracy tradeoff (SAT). In this talk I discuss the neural substrate of SAT using data from functional magnetic resonance imaging (fMRI), diffusion tensor imaging (DTI), and ultra-high resolution 7T MRI. In a series of experiments participants were presented cues that indicated different requirements for response speed. Application of the Linear Ballistic Accumulator model (LBA; Brown & Heathcote, 2009) confirmed that these cues selectively affected response thresholds. Individual LBA parameters were then correlated with functional and structural MRI measures, revealing the involvement of the pre-supplementary motor area (pre-SMA) in concert with the striatum; this finding is consistent with the fact that excitatory signals from pre-SMA to striatum release the motor system from inhibition, thus facilitating faster but possibly premature actions. The present results suggest that individual differences in both brain function and brain structure translate to individual differences in the efficacy with which people change response thresholds.