The Expanding Spotlight uses Gaussian apertures centered on the observers' fixations that dynamically and progressively expand (at a rate of 1degree every 25ms) as a function of fixation time, such as the longer the fixation duration, the larger the Spotlight aperture size becomes. The Spotlight aperture is contracted to 2 degrees (foveal region) at each new fixation.
This novel technique has the tremendous advantage to simultaneously identify the qualitative use of information and to provide an estimate of the quantity of information necessary at each fixation location to achieve this process, in a parametric unbiasedmanner.
Miellet, S., Vizioli, L., He, L., Zhou, X., & Caldara, R. (2013). Mapping face recognition information use across cultures. Frontiers in Perception Science, 4, 34. [PDF]