Final answer:
There are six personality types in John Holland's theory, corresponding to the RIASEC acronym. The theory holds that work satisfaction and success are likely when one's job environment matches the dominant personality type among the six.
Step-by-step explanation:
In John Holland's theory, there are six personality types. These types are Realistic, Investigative, Artistic, Social, Enterprising, and Conventional, commonly remembered by the acronym RIASEC. This theory posits that people are happier and more successful if their work environment matches their personality type. The types help individuals understand where they might be most satisfied and effective in their careers. Holland suggested that most people are a combination of these types, but one or two are usually more dominant.
Another well-known personality framework is the Five Factor Model, also known as the Big Five, which includes the factors: openness to experience, conscientiousness, extroversion, agreeableness, and neuroticism. The acronym OCEAN is used as a helpful mnemonic to remember these factors. Between Cattell's 16 factors, Eysenck's two-factor system, and the Five Factor Model, it is recognized that modern psychology strives to categorize the complex aspects of human personality into understandable models.