To oversimplify a secure attachment, the child develops a strong internal representation of the Other. My understanding is that this contributes to the ability to "hold both truths," enabling repression to occur over suppression and splitting. Cognitive development is a complicated process, but seems to involve a relationship with the world in which experience and information must be held, 'internalized,' etc, to develop into knowledge, understanding, and the capacity to see multiple perspectives. I am wondering about research that correlates any level of abstract thought with the internal representation of the attachment figure.
In broader terms (but perhaps too broad), what do we know about how cognitive development is influenced by emotional development?