Discerning Ambient/Focal Attention with Coefficient K.

We introduce coefficient K, defined on a novel parametric scale, derived from processing a traditionally eye-tracked time course of eye movements. Positive and negative ordinates of K indicate focal or ambient viewing, respectively, while the abscissa serves to indicate time, so that K acts as a dynamic indicator of fluctuation between ambient/focal visual behavior. The coefficient indicates the difference between fixation duration and its subsequent saccade amplitude expressed in standard deviation units, facilitating parametric statistical testing. To validate K empirically, we test its utility by capturing ambient and focal attention during serial and parallel visual search tasks (Study 1). We then show how K quantitatively depicts the difference in scanning behaviors when attention is guided by audio description during perception of art (Study 2).