Final answer:
Martin Seligman realized that his theory of authentic happiness was lacking the concept of meaning and purpose in life, which led to the development of the PERMA model that includes this vital aspect of well-being alongside positive emotions and character strengths.
Step-by-step explanation:
Martin Seligman, renowned for his contributions to positive psychology, initially addressed the concept of authentic happiness in his theory. However, he later recognized that something crucial was missing from his original framework. What did Martin Seligman think was missing from his original theory of authentic happiness? The answer is the concept of meaning and purpose in life.
Seligman's evolution of thought led him to the understanding that while positive emotions and character strengths are vital, they do not entirely capture the complexity of human well-being. Therefore, he introduced the model of well-being in addition to his authentic happiness theory, emphasizing the four elements: Positive emotion, Engagement, Relationships, Meaning, and Achievement (PERMA). This model suggests that a sense of purpose and meaning in life enhances one's fulfillment beyond the transient positivity of emotions.