On vs. off-object probes produce differential ERPs and reversal latencies in binocular rivalry

Binocular rivalry occurs when two highly incompatible images are presented simultaneously but separately to each eye. Rather than settle on one image, perception alternates between the two. Prior research has shown that briefly-presented probes modulate perception such that dominant-eye probes decrease the likelihood of a reversal while suppressed-eye probes increase reversal likelihood (measured as reversal latency from probe onset). We have previously shown that probe modulation varies as a function of whether probes appear on vs. off rivalry objects. Specifically, relative to off-object probes, on-object probes increase reversal likelihood when they appear in the suppressed-eye, and decrease reversal likelihood when they appear in the dominant eye. This suggests that probes boost activity for the object over which they appear, perhaps by drawing attention to that image. Here, we use ERPs to better understand why on-object probes more effectively modulate perception, separately as a function of whether probes appear in the suppressed or dominant eye. We replicate prior behavioral work showing that on-object probes modulate perception more effectively, increasing reversal likelihood for on-object suppressed-eye probes while reducing reversal likelihood for on-object dominant-eye probes. Critically, however, we show that on- vs. off-object probes significantly differ in N2 and P3b ERP activity, both of which have been implicated in higher-order attention-related processes. Relative to off-object probes, on-object probes presented to the suppressed-eye elicit increased N2 activity followed by increased P3b activity. Relative to off-object-probes, on-object probes presented to the dominant-eye also elicit increased N2 activity, but are not followed by increased P3b activity. The data suggest that suppressed-eye on-object probes draw attention (as indexed by N2 amplitude time-locked to probe onset) to the object over which they appear, thereby increasing the likelihood of a perceptual reversal. Meeting abstract presented at VSS 2017