Explanation:

- David Cooper: A noted psychiatrist, associated with the anti-psychiatry movement like Laing, but did not specifically refer to the family as a "matrix."

- R. D. Laing: Correct Answer. Laing, a famous psychiatrist, referred to the family group as a "matrix," especially in the context of social and psychological development.

- Edmund Leach: An anthropologist known for his work on kinship and marriage, but did not refer to family as a matrix in the context asked here.

- Vogel and Bell: Known for their studies in the sociology of the family, but did not use the "matrix" term for family group.