The French mathematician and philosopher Blaise Pascal once wrote,
‘The heart has its reasons which reason knows not of.’
This message – that emotion and cognition are separate systems that seldom interact – has a long history in Western philosophy and science:
The rational mind is seen as reasonable, logical, and linear. The rational mind is excellent at developing level-headed explanations for behavior (it is so good, it has consumers convinced that they are rational shoppers). The rational mind has overlooked the existence of the emotional mind ever since Descartes’ famous but flawed line, “I think, therefore I am.”
The emotional mind is seen as associative, often subconscious, irrational and intense. The emotional mind is more powerful than the rational mind. It works more quickly than the rational mind. This is partially due to the order in which the brain evolved over millions of years.
Those areas of the brain which are primarily responsible for emotions, the hippocampus, the amygdala, and the insula, among other regions, developed much earlier than the part of the brain responsible for rational thought, the neocortex.
However, the past two decades have seen a significant shift in this view as behavioral and neuroscience research have demonstrated that emotion and cognition not only interact, but that their integrative operation is necessary for people to make sound decisions and simply get along.
Psychologists, neuropsychologists, neuroscientists, and others in the field of emotion research have developed a number of approaches to describe and measure emotions. Two of the most fundamental approaches are the categorical (discrete) approach and the dimensional (continuous).
The categorical approach by Ekman and Friesen  proposes that there are some “fundamental” emotions, where the term fundamental represents those patterns of responses to the world that evolution has equipped us with, due to their necessity for our survival. All other emotions are somehow derived from this small set of simpler emotions. They postulated the initial ”Big Six“ emotions, which are happiness, sadness, fear, surprise, anger, and disgust (Ekman later expanded his list of basic emotions, including a range of positive and negative emotions, not all of which are encoded in facial muscles). 
The dimensional model describes emotions in two independent dimensions (arousal, pleasure) in a Cartesian Space . Based on these two dimensions, Russell created a ‘circumplex of emotions’ . In this model, each emotion has a specific location on the circumplex. Emotions, therefore, are not perceived in categories but in much more complex and fluent manner. They can be measured according to valence and arousal, where valence refers to whether the emotion is positive or negative and arousal refers to the intensity.
 Ekman, P., Friesen, W. V. 1971. Expression and the nature of emotion. In K. Scherer and P. Ekman (Eds.), Approaches to emotion.
 Russell, J. A., Fernandez-Dols, J. .M. 1997. The Psychology of Facial Expression. Cambridge University Press, Cambridge.
 Russell, J.A. 1980. ‘A circumplex model of affect’. Journal of Personality and Social Psychology, 39, 1161-1178.
 Paul Ekman (1999). Basic Emotions. In T. Dalgleish and M. Power (Eds.). Handbook of Cognition and Emotion. Sussex, U.K.: John Wiley & Sons, Ltd
Emotions and the Subconscious Drive Behavior
Emotions and the subconscious are the primary driving forces behind people’s behavior, including buying behavior. Fully engaged people are strongly emotionally attached. On the other hand, actively disengaged people are detached. They are ‘detractors’ that may become virulently antagonistic toward your company or brand, and they’re usually eager to tell others exactly how they feel.
The challenge has been to develop a tool to accurately identify and measure conscious and subconscious emotions in real time.
e.mote® – Measuring Engagement and Predicting Behavior
Inspiration Engine’s e.mote® is based upon a simple algorithm taken from both the Categorical and Dimensional models of measuring emotional engagement. A set of discrete emotions built into an emoticon uses facial expressions to continuously display emotions in terms of valence (positive or negative) as well as their intensity (arousal). Expressions provide a valid set of complex emotional stimuli that avoid all of the methodological baggage associated with laboratory studies of word lists and verbal material in general. The combination of the expressed emotion’s valence and intensity is highly predictive of people’s behavior.