When incompatible images are presented to corresponding retinal locations of each eye, perception becomes unstable and alternates between the images. This phenomenon is known as binocular rivalry (Wheatstone,
1838; see Blake & Wilson,
in press for a recent review). During rivalry, one of the images will be temporarily dominant in perception, while the other will be suppressed. Several studies on the nature of binocular rivalry suppression show that sensitivity to probes presented in the suppressed image is reduced by a factor of about 2 to 3 (Blake & Fox,
1974; Ooi & Loop,
1994; O'Shea & Crassini,
1981). Traditionally, this suppression of an image during binocular rivalry is considered to be non-selective: All inputs from the suppressed eye (i.e., the eye to which the suppressed image was presented) are thought to be uniformly affected (e.g., Blake,
1989; Blake & Fox,
1974; Blake & Logothetis,
2002; Blake, Westendorf, & Overton,
1980; Fox & Check,
1966,
1968; Freeman, Nguyen, & Alais,
2005; Nguyen, Freeman, & Wenderoth,
2001; Wales & Fox,
1970). However, evidence that challenges this view is accumulating (Alais & Parker,
2006; O'Shea & Crassini,
1981; Paffen, Alais, & Verstraten,
2005; Stuit, Cass, Paffen, & Alais,
2009; Vergeer & van Lier,
2010). These latter studies argue that the magnitude of suppression during rivalry depends on the similarity in feature content between the competing images. For example, sensitivity to oriented probes presented in a suppressed image depends on the orientation difference between the probe and the suppressed image (Stuit et al.,
2009). A similar dependency was shown for spatial frequency content. In addition, these studies suggest that the above dependency is only apparent for the features that
drive the interocular conflict. For instance, variations in the magnitude of suppression for different combinations of spatial frequencies can only be found when rivalry is based on conflicting spatial frequencies of the images, not when the images have conflicting orientations with the same spatial frequency (Stuit et al.,
2009). These findings show that suppression during binocular rivalry is indeed
(feature) selective: Inputs originating from a suppressed image are not necessarily affected equally.