First let the Mage be proficient with Detect Magic.
Let him then select a person or place to be examined.
Let the Mage then Read the person or place, as in Detect Magic.
With this spell however, let the Mage read more than the impressions upon the place or person. He shall leave himself open to feel as the person feels.
With proficiency and experience, the Mage will be able to determine not only the target's tendencies, but the specific emotions attached to them.