Threshold detection of intensity flashes in the blowfly photoreceptor by an ideal observer

Detection of intensity flashes in the blowfly photoreceptor is limited by photon noise in the input signal as well as noise contributed by transduction components within the photoreceptor. Our analysis uses an ideal observer and a model of blowfly phototransduction to compute the threshold for optimal detection of intensity flashes as background intensity varies. We find that detection threshold increases with background light intensity according to a power function, that the threshold for low light levels is limited mainly by the photon noise, and that the threshold at high light levels is limited mainly by the channel noise.