Figure 2.

Autocorrelation function of fMRI time series during rivalry. (A) Data from a voxel in the calcarine sulcus (V1; x = −12, y = −96, z = −3). (B) Data from a voxel in the middle occipital gyrus, close to the lateral occipital sulcus (BA 18/19; x = 36, y = −87, z = 9). (C) Synthetic data from a model of hemodynamic responses to perceptual alternations. Autocorrelations are shown for increasing lags (expressed in number of scans) with all time series mean-corrected and normalized to unit SD. Points above or below the dashed horizontal lines exceed the 99% confidence limit for significant effects. Note the absence of significant correlation in V1 for all but the trivial zero lag. In contrast, the time series from BA 18/19 and the model both show significant correlation between successive fMRI measurements (corresponding to a time lag of 4.1 s).