Most studies on bistable perception have used a single bistable stimulus—with the notable exception of binocular rivalry necessarily involving two stimuli. The first investigation of bistability with several bistable stimuli—two Necker cubes presented in the two hemifields—was conducted by Flugel (
1913) who reports that observers can dissociate their perceptual alternations when asked to attend to a single stimulus. Studying the effects of a contextual stimulus on bistable perception can provide relevant evidence to disentangle and improve models of perception. For instance, whether contextual stimuli alter the dynamics of bistability may bring evidence that not only local processes—the limited neuronal assemblies activated in alternance by a focal stimulus in visual areas—but also long-range processes determine bistable perception dynamics. An effect of a context on bistability may involve lateral low-level interactions (Klink, Noest, Holten, van den Berg, & van Wezel,
2009; Ramachandran & Anstis,
1985), feedback from remote visual areas (Rock, Hall, & Davis,
1994; Strüber & Stadler,
1999; Toppino,
2003), more cognitive top-down processes, including decisional, attentional, inferential, or volitional effects (Kornmeier, Hein, & Bach,
2009; Meng & Tong,
2004; van Ee, van Dam, & Brouwer,
2005; for a review, see Long & Toppino,
2004), or depend on a specific subcortical modulatory influences (Carter & Pettigrew,
2003; Miller et al.,
2000; Ngo, Liu, Tilley, Pettigrew, & Miller,
2008; Pettigrew,
2001).