Emotion analytics

Introduction endnote 4, from How Emotions are Made: The Secret Life of the Brain by Lisa Feldman Barrett.
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Companies like Affectiva and Realeyes offer to help businesses detect their customers’ feelings through 'emotion analytics.'

Emotion analytics is an emerging field with the goal to identify human moods, stress levels, and emotions from text and from physical measurements of the voice, face, and body. Some companies that claim to be able to objectively measure human sentiments in this way include Affectiva, Autoemotive, Apple's Emotient, EQ-Radio, Sensoree, and Zensorium.