1. A method for predicting viewership of a content stimulus comprising: exposing an audience to the content stimulus using a media device communicatively coupled to a computer processing system, the computer processing system receives data relating to the content stimulus; measuring a biologically based response during the exposure of the content stimulus using a biometric sensor device communicatively coupled to the computer processing system, the computer processing system receives data related to the biologically based response; and executing instructions with the computer processing system to: divide the content stimulus into a number of intervals; determine for each interval an intensity value as a function of the biologically based response and a synchrony value as a function of a rate of change of the biologically based response for members of the audience during each interval, the synchrony value representing a number of members of the audience with a same biologically based response; obtain an engagement score for each interval of the content stimulus, the engagement score being a function of the intensity value and the synchrony value; use the engagement score to determine a metric including one or more of negative buildup, positive buildup, average engagement score, maximum engagement score, or combinations thereof; and generate for display or output information indicating a prediction of viewership based on the metric.