Fig. 1.

Graphical depiction of the simple and competing stimulus paradigms. The gray circles represent a neuron's visual (dark gray) and auditory (light gray) excitatory receptive fields (ERFs). A: the simple paradigm: 2 stimuli are either separately or jointly presented inside the neuron's ERFs. This excitatory stimulus is denoted by the subscript “i.” B: the competing paradigm: stimuli are presented simultaneously inside (excitatory stimulus) and outside (competitor stimulus) the neuron's ERFs in all possible combinations. The competitor stimuli are denoted by the subscript “c.” The dotted lines represent the vertical meridian.