Explained variance within averaged and non-averaged BOLD signals for different noise levels.

<p>This figure shows the amount of variance explained for averaged and non-averaged BOLD signals based on pRF parameters estimated from these signals as a function of the percent stimulus-related signal in the raw data. The explained variance for non-averaged signals (black line) scales linearly with the percentage of stimulus-related signal in the raw data. That is, the estimated pRF parameters explain as much variance of the overall signal as is actually due to stimulation. For averaged signals, the amount of variance explained both starts off higher and reaches a plateau faster than for the non-averaged signal. This effect is stronger for signal averaged across 20 cycles (blue line) than for signal averaged across 3 cycles (red line).