Even with a constant task, human performance fluctuates in time-scales from seconds to minutes in a fractal manner. In a recent study a research group found that the individual variability in the brain dynamics as indexed by the neuronal scaling laws predicted the individual behavioral variability and the conscious detection of very weak sensory stimuli. These data indicate that individual neuronal dynamics underlie the individual variability in human cognition and performance. Results may also have a strong impact in understanding the neuronal mechanism of neuropsychiatric diseases in which behavioral dynamics are abnormal.