Fig. 9.

Correlation between average normalized similarity and average synergy activation correlation when synergy activation variability was included in the analysis (signal-to-noise ratio of −20 dB, −10 dB, 0 dB, 10 dB, and 20 dB). Results are shown for the three algorithms with the strongest correlation: NNMF, PCA, and pICA. As synergy activation variability increased, average synergy activation decreased. NNMF and pICA had significant increases in normalized similarity with increasing variability, but other algorithms, such as PCA, had smaller changes in normalized similarity.