I have been reading the Opposable Mind by Roger Martin and have come across many similarities between the method of integrative thinking described in the book and the practice of qualitative research.
One of the key elements of successful design research is the practitioner's ability to understand people's (be it users of a service, customers, etc.) motivations, needs, and attitudes. Throughout the research process the practitioner aims to understand people by observing and supplementing his understanding by asking the right questions. A good practitioner will empathise with his subjects without necessarily agreeing with what is observed or discussed. The right approach and skill to separate ones own preconceived ideas and beliefs from the subjects' mental models is key to the success of any design research project. The practitioner will later use his experience, subject matter expertise, and understanding of client needs to design a service or product to meet those needs.
This approach of understanding and empathising in order to design a user centric solution is similar to the method of assertive inquiry described by Martin in the book:
"When you use assertive inquiry to investigate someone else's mental model, you find saliences that wouldn't have occurred to you and causal relationships you didn't perceive. You may not want to adopt the mental model as your own, but even the least compelling model can provide clues to saliences or causal relationships that will generate a creative resolution. ... assertive enquiry involves a sincere search for another's views. ... It aims to learn about the salient data and causal maps baked in to another person's model, then use the insight gained to fashion a creative resolution." p.157