Seeing slow and seeing fast: two limits on perception

Trends Cogn Sci. 2009 May;13(5):216-21. doi: 10.1016/j.tics.2009.02.005. Epub 2009 Apr 20.


Video cameras have a single temporal limit set by the frame rate. The human visual system has multiple temporal limits set by its various constituent mechanisms. These limits seem to form two groups. A fast group comprises specialized mechanisms for extracting perceptual qualities such as motion direction, depth and edges. The second group, with coarse temporal resolution, includes judgments of the pairing of color and motion, the joint identification of arbitrary spatially separated features, the recognition of words and high-level motion. These temporally coarse percepts might all be mediated by high-level processes. Working at very different timescales, the two groups of mechanisms collaborate to create our unified visual experience.

Publication types

  • Review

MeSH terms

  • Cerebral Cortex / physiology
  • Discrimination, Psychological*
  • Flicker Fusion / physiology
  • Humans
  • Reaction Time / physiology
  • Sensory Thresholds / physiology*
  • Time Factors
  • Time Perception / physiology*
  • Visual Pathways / physiology*
  • Visual Perception / physiology*