Abstract Human performance in the domain of signal detection is analyzed with respect to the formation of streaks. Streakiness was found to be a general property of auditory and visual discrimination in the sense that correct and incorrect responses have a positive sequential dependency. Success tends to follow success and failure tends to follow failure. Level of streakiness was discovered to be a function of the attentional demand required by the discrimination. Discriminations that make the least demand on attentional resources produce the highest level of streakiness. Monte-Carlo simulations of the observed data sequences suggest that streaky performance is a residue of wave-like variations in perceptual and attentional resources.