Abstract
In Motion-Induced-Blindness (MIB), salient targets superimposed on a global moving-dots pattern are perceived to disappear and reappear alternatively after prolonged viewing (Bonneh, Cooperman, & Sagi, 2001). This oscillation of target disappearance and reappearance in MIB reflects an alternation state of conscious experience that occurs with unvarying stimulus over time. However the relationship between this kind of alternation state and the ongoing brain activities has been less studied (cf. Donner, Sagi, Booneh, and Heeger, 2008). Here we investigate the changes in the frequency spectrum of the electroencephalogram (EEG) on the perception of MIB. We collected brain activities specifically associated with the timing when observers reported (1) the illusory disappearance of the MIB target (the MIB condition), (2) the real disappearance of the target (the real-disappearance condition), and (3) the motor responses as in the former two conditions but now a blank field was seen (the motor-control condition). The average power spectra of the 1 sec pre- and post-response periods were computed for the three conditions, and so were the amplitudes of total power and relative band powers of the delta (0.5–4 Hz), theta (4–7.5 Hz), alpha (7.5–13 Hz), beta (13–30 Hz), and gamma (30–70 Hz) frequency bands. The results revealed that MIB targets led to larger and smaller amplitude spectra in the relative power of the delta and alpha bands, respectively, compared to the motor control. Moreover, MIB targets led to smaller amplitude spectra both in the delta and alpha bands compared to the real-disappearance condition. These results imply that the perception of the disappearance of MIB targets could be reflected in the delta and alpha rhythms of the EEG, which may explain significant variability in the perceptual processes.
NSC 95-2413-H-039-002, 96-2413-H-039-001-MY2, and 96-2413-H-002-009-MY3.