What is Behavioral Intent Prediction?

For decades, behavioral intent prediction has been the holy grail of business. The more accurately we can predict when someone will act and what triggers will precipitate that action, the more effective we can be in everything from sales to medical diagnosis. Well before AI and Machine Learning enabled a more in-depth analysis of big data sets, studies were being performed to analyze the relationship between stated intentions and the subsequent behavior of consumers. Did people follow through on their intentions? How honest were they in stating those intentions?