Mayer et al., view intelligence as a general descriptive term referring to a hierarchy of mental abilities. This model consists of several hierarchical levels: basic mental abilities, broader cohesive groups of abilities and on the highest level general intelligence (of all domains).

Emotional intelligence is defined as the ability to carry out accurate reasoning about emotions and the ability to use emotions and emotional knowledge to enhance thoughts. Almost all mental activities involve emotion and intelligence, but the difference with Emotional Intelligence is the involvement of a primary focus on a specific area of problem solving.

Different approaches to emotional intelligence in the literature:

1. Theoretical Approaches to Emotional Intelligence

2. Specific-Ability Approaches to Emotional Intelligence: consider individual mental capacities important to EI. Some of these abilities are emotional perception (nonverbal perception is recognizing the social information about power and emotional expressions), use of emotional information in thinking (people with higher EI can be more objective when something is related to emotions), reasoning about emotions and emotion management.

3. Integrative-Model Approaches to Emotional Intelligence: regard EI as a cohesive, global ability, in which several specific abilities are related to the overall sense of EI. An example of an integrative model is the Four-Branch Model of EI, in which EI is considered as the joining abilities of four areas: accurately perceiving emotion, using emotions to facilitate thoughts, understanding emotions and managing emotions.

4. Mixed-Model Approaches to Emotional Intelligence: mixes noncognitive, capabilities, competences or skills, emotionally and socially intelligent behavior and dispositions from the personality domain.

Measuring Emotional Intelligence is possible in very many ways. The key question by choosing for a specific test is: do these tests measure what they claim to? An adequate test design has a content evidence of validity (do I measure what I want to know?), response-process evidence of validity (linking individual answers to criterion of correctness), reliability of emotional intelligence measures (consistency) and validity evidence from factor structure.

Topics, which can be predicted by emotional intelligence:

1. Social Relations in Childhood and Adolescence: EI is positive correlated with good social relations and negative correlated with social deviance.

2. Social Relations in Adulthood: Higher EI leads to greater self-perception of social competence and a decreased use of destructive interpersonal strategies.

3. Scholastic Outcomes from Grade school to College: Higher EI leads to higher academic achievements, but not always to higher grades because that is influenced by IQ.

4. Emotional Intelligence at Work: High EI gives better social relations during work performance and in negotiations.

5. Psychological and Physical Well-Being: EI is correlated with greater life satisfaction and self-esteem and lower ratings of depression.

6. Better family and intimate relationships.

7. High EI individuals are perceived more positively by others.