According to a study in the Frontiers in Psychology Journal effectiveness of ads on YouTube can be predicted by neural networks and neuroscience-based metrics with 82.9% accuracy (Guiexeres, et. al 2017). The biometric markers were things like brain response, heart rate variability and eye tracking.
As we get aroused we often collect, encode information which in turn can lead to better recall. There is an emotional response to some of the things we like and don't like. By using these biometric markers we are better able to determine on a deeper neural level what people like and don't like.
While the study was limited with 35 participants it does highlight the ability to test advertisements, images, and possibly word choices on target populations before actually spending lots of money on marketing. We may know what is better what will create a brand versus what might not. Our marketing choices will be much more pointed and effective with pre-testing campaigns.
Guixeres, J. et. al. (2018). Consumer Neuroscience-Based Metrics Predict Recall, Liking and Viewing Rates in Online Advertising. Frontiers in Psychology, 8.