FIGURE 8.

Event-related averages of channels-of-interest in participant 17. The two graphs on the left are event-related averages from the fifth answer decoding run, in which the participant encoded a “yes” answer. The two graphs on the right are event-related averages from the sixth answer decoding run, in which the participant encoded a “no” answer. The top two graphs depict the oxygenated hemoglobin (HbO) response, whereas the bottom two graphs depict the deoxygenated hemoglobin (HbR) response. Each graph is the event-related average of five individual trials, with the darker average signal line and its standard deviation (lighter colored band surrounding the average signal line). Notice the absence of a typical hemodynamic response function during both tasks: there is no clear positive deflection in HbO, nor a negative deflection in HbR. The gray band from 0 to 10 s signifies the mental imagery time interval.