Six basic human emotions are happiness, fear, surprise, sadness, anger and disgust, according to Julie Beck for The Atlantic. However, the media outlet reported in February 2014 on a study conducted at the University of Glasgow that suggests there are four basic emotions because anger and disgust were alike, and fear and surprise appeared similar in facial expressions. The study measured responses of observers to computer-generated images of human faces.
Beck explains psychologists determined that the differences between anger and disgust, along with fear and surprise, are sociological rather than biological. This is because the emotions are different inside the mind, but the external reactions appear the same to observers. Distinctions between biological and sociological emotions denote human evolution since humankind no longer needs survival instincts in the wild.
Psychologist David Straker compiled several theorists and their lists of basic human emotions on his website ChangingMinds.org. Magda B. Arnold believed there are 11 basic emotions, adding courage, dejection, desire, despair, hate, hope and love to fear, sadness, anger and disgust. Caroll Izard maintains 10 basic emotions, including contempt, distress, guilt, interest and shame on top of disgust, anger, happy, surprise and fear.
Straker explains basic emotions have secondary emotions to further classify human feelings. For instance, joy has the subcategories cheerfulness, zest, contentment, pride, optimism, enthrallment and relief. Each of these secondary emotions are further broken down into tertiary emotions. For example, optimism also means eagerness and hope.