2007 Sensory Physiology

light represents ELECTROMAGNETIC energy - it has the properties of both particles (photons) and waves (FREQUENCY - perceived as colour; and INTENSITY - perceived as brightness)

visible light (i.e., the components of the spectrum that humans can see) has a wavelength between 350 and 750 nm

• dark-adapted photoreceptors (rods) can detect light as dim as 1 photon

the light that is perceived is reflected light - e.g., an object is detected as green if it reflects light of ~530 nm