Fig. 2.

Effect of signal prewhitening on fNIRS data. Prewhitening using an autoregressive filter removes serially correlated errors in the signals. In panels (a) and (b), raw signals with no motion artifacts and with artifacts are shown. After filtering, the innovation (prewhitened) versions of these signals is shown in panels (c) and (d). This figure shows the same data presented in Fig. 1. (a) No motion (raw signal), (b) motion affected (raw signal), (c) no motion (prewhitened), (d) motion affected (prewhitened), and (e) autocorrelation.