After a yawn in my session today the circle got bigger and stayed that way for a long time. What puzzled me is that the line on the graph was so close to the baseline during that time.
When the circle is small, the line dips below the baseline so I expected the line to go above the baseline when the circle got big. I am assuming the bigger the circle, the more my frontal cortex is oxygenated therefore the higher the line on the graph should go.
What information am I not knowing here?