Allen F. Harrison and Robert M. Bramson, both researchers of human behavior, published The Art of Thinking in 1981 (later revised and republished). It is the popular, accessible cousin of Sternberg's academic framework — written for general audiences, complete with self-tests and everyday examples.
Their framework identifies 5 basic styles of thinking, derived from empirical research on how people actually approach problems, decisions, and disagreements in everyday and professional life. The associated psychometric instrument is called the InQ (Inquiry Mode Questionnaire).
The central claim: everyone has a dominant thinking style (or combination of styles) that shapes how they perceive problems, what information they seek, how they make decisions, and how they communicate. These styles are shaped by fundamental beliefs about reality — beliefs so deeply held that they're often invisible to the person who holds them.
Core belief: Reality is conflict. Truth emerges from contradiction.
Synthesists see the world in terms of opposites and polarities. When you say black, they think white. When you say long, they think short. They are drawn to conflict and contradiction not because they're argumentative (though they may appear so), but because they believe that genuine understanding requires holding opposing views in tension.
Core belief: There is a better way. Everything can be improved toward an ideal.
Idealists take a broad, holistic view of things and are oriented toward the future. They think about goals, values, and what should be. They are big-picture people who are less interested in detail and more interested in direction.