The research that we report in this chapter was motivated by three surprisingly simple questions that turn out to have deep consequences for cognitive brain architecture:

Like any other form of computation, brain computing takes time. Thus, it may seem obvious that each of our decisions should take some minimal duration, ultimately linked to axonal, synaptic, and dendritic propagation delays. Yet the intriguing question is: Why does it take so much time to take a decision? We do not necessarily refer here to the arbitrary long durations of certain choices (although this too plays its part). It can take hours, days, or months to choose where and for how long to go on vacation, and with whom, and how, and so on and so on. Decision difficulty is illustrated by the metaphor of Buridan’s ass (honoring the 14th-century French philosopher Jean Buridan), who supposedly died when placed in between a stack of hay and a pail of water, unable to decide whether to eat

or drink first. But far from the limits of starving or pathological decision making, simply deciding which of two numbers is larger, or which of two tones is of a higher pitch, takes between 500 and 1500 ms-a surprisingly long time, when considering synaptic delay and the timing of selective responses to sensory stimuli.