## 3 Results
### Cognitive Attention Test Pilot Human Study with SCISCCO
Unsatisfactory signal quality was defined as when the SNR between two adjacent measurements was more than three standard deviations from the mean. Finally, yet another three participants had more than three out of nine data blocks with HbO concentrations lower than the baseline, and they were discarded because we expected increasing HbO during the attention blocks, as established by prior research [41]. All of these eight participants discarded were probably due to improper placement of the probe, motion artifacts, or other environmental fluctuations leading to data errors. After the first step in our data screening of removing the outliers, we were left with 17 participants' data out of the original 25 participants. We then further filtered the data in two different ways (described in more detail below and in Appendix B) to remove artifacts in the data sets from these 17 participants that may have been related to motion during the data acquisition time. Both screening methods provided comparable results and supported the following hypothesis: during the attention task, although the HbO concentration increased, the redox state of CCO decreased. It is noteworthy that HbO and CCO are not always uncorrelated when measured in other parts of the body. For example, in the blood pressure test previously discussed, CCO was more or less constant, while the HbO increased initially (Figure 8). In the second screening step, we did not accept all nine blocks of attention test data for the 17 participants remaining after removing the outliers. To further remove data affected by motion artifacts, we used one of two second screening methods. The first method is called the \"best of six\" approach, described further in Appendix B. The table in Figure 16 shows the results of applying the best of six screening method after the outliers were  
Figure 15: Illustration of the SCISCCO system detection time (orange blocks) relative to the attention test protocol. During each 60-s attention task, 2 data blocks were collected. removed. Figure 17 illustrates the change in HbO, HbR, and the redox state of CCO after applying \"best of six\" screening. The lines show the average values, while the error bars indicate the standard error. During the attention test period, the HbO increased on average, while the redox state of CCO decreased on average. The HbR was more unpredictable, but this may be because HbR is generally harder to measure and has a lower signal-to-noise ratio in the measurement. As an alternative second screening method, we applied \"HbO increasing\" processing after removing the outlier participants. This alternative second screening yielded approximately the same results of HbO increasing and the redox state of CCO decreasing during the attention test, although with a larger contrast for the CCO change and HbO  
Figure 16: Table illustrating the “best of 6” screening of the 17 participants after removing the outliers. The second column represents the number of data blocks with CCO decreasing. Figure 17: Using the “best of six” screening, average of the change in HbO, HbR, and the redox state of CCO during the attention test. The error bars indicate the standard error. change. The table in Figure 18 illustrates the data selection. For the \"HbO increasing\" data selection method, Figure 19 shows the change in HbO, HbR, and the redox state of CCO during the attention test. The lines correspond to the averages of the data, while the bars indicate the variance in the measurements. As in the previous analysis, we found that the HbO increased during the attention test and the CCO decreased. With the HbO screening method, the amount of the concentration change was larger, but the results were consistent with the \"best of six\" approach. As before, the HbR did not show a clear trend, which may have been due to the difficulty of measuring HbR. Figure 19: Using the “HbO increasing” screening, average of the change in HbO, HbR, and the redox state of CCO during the attention test. The error bars indicate the standard error.