Figure 4.

Classification accuracy remains high with scans as short as 1 min. The classification algorithm was tested initially on the full 10-min scans but then on increasingly shorter scan lengths. In each case, the shorter scan lengths are taken from the beginning of the scan (i.e. 0.5 min refers to the first 30 s of the scan). Eleven different scan lengths from 30 s to 10 min were evaluated. The orange line refers to the overall accuracy in distinguishing all 4 states. Accuracy for individual states is shown in the other 4 colors. An accuracy of 25% reflects chance level classification. The overall accuracy remains at 80% with just 1 min of data. With scan lengths below 1 min, overall accuracy tends to decrease, though all 4 scans were identified with significant accuracy with only 30 s of data (P < 0.001).