What EQ actually is
Emotional intelligence (EI or EQ) refers broadly to the ability to perceive, use, understand, and manage emotions — both one's own and others'. The concept was popularised by Daniel Goleman's 1995 book, which made dramatic claims about EQ being more important than IQ for success in life. These claims were not grounded in the research literature at the time and remain overstated today.
Models of emotional intelligence
There are two main approaches to measuring EQ, with very different psychometric properties. Ability models (developed by Mayer, Salovey, and Caruso) treat EQ as a genuine cognitive ability, analogous to IQ — measured with performance tasks where responses have correct and incorrect answers. The Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT) is the main ability-model measure.
Mixed models (Goleman, Bar-On) treat EQ as a combination of personality traits, social skills, and motivation — measured with self-report questionnaires where you rate your own abilities. These measures typically produce higher correlations with outcomes, but this may be because they measure well-established personality dimensions (especially Agreeableness, Emotional Stability, and Conscientiousness) rather than a distinct "EQ" factor.
What EQ predicts
EQ ability measures (MSCEIT) have been found to predict: job performance, particularly in roles requiring interpersonal interaction and negotiation (r≈0.24); leadership effectiveness, with moderate correlations across studies; mental health and wellbeing; and relationship quality. These are real and non-trivial effects.
Mixed-model EQ measures show stronger correlations with outcomes, but these are inflated by overlap with personality traits and by self-serving biases in self-report (people who rate themselves high on EQ also tend to rate themselves highly on other traits).
EQ vs IQ: which predicts what
IQ is a stronger predictor of academic achievement, job training performance, and performance in cognitively complex roles. EQ adds incremental prediction of job performance beyond IQ and personality, particularly in roles requiring emotional labour — management, sales, customer service, counselling, and teaching.
The "IQ doesn't matter after you reach a threshold" argument has some support: above IQ 120 or so, further IQ gains predict less incremental job performance. In this range, interpersonal and emotional competencies may indeed become relatively more important differentiators. But this is different from saying EQ is "more important" than IQ overall.
The scientific controversy
The scientific community is more sceptical of EQ claims than the popular press suggests. A 2004 paper by Locke argued EQ is not a valid construct. A 2005 review by Mayer, Roberts, and Barsade defended ability-model EQ while distancing it from the popular mixed-model approaches. The debate centres on whether EQ measures something genuinely distinct from established cognitive and personality variables — the evidence is mixed.
An honest verdict
Emotional intelligence as measured by ability tests (MSCEIT) is a real, modestly valid predictor of outcomes, with validity lower than IQ but meaningful in interpersonal roles. The popular version of EQ — as presented in bestselling books and corporate training — overstates the evidence substantially and confuses genuine emotional ability with personality and social skills.
The framing of "EQ vs IQ" is itself misleading. They measure different things, both contribute to outcomes, and their relative importance depends heavily on the domain and role in question.