We shouldn't fear a bit of messiness in our interactions with people we care about, says psychologist Dr Ed Tronick.
He recently co-authored the book The Power of Discord: Why the Ups and Downs of Relationships Are the Secret to Building Intimacy, Resilience, and Trust with pediatrician Dr Claudia Gold.
Dr Tronick was well-known for the 1975 'Still Face Experiment' which explored how well infants can read emotions and react to them.
At the time, it was generally believed infants couldn't read faces, Tronick tells Kathryn Ryan, but we now know that a sense of emotional connection is absolutely critical for a baby's social development.
"The experiment demonstrated that when you changed the mother's behaviour … that had a profound effect on the infant and how they wanted to engage with the mother."
When the mother and infant started interacting again - after she had presented a still face - they very quickly got back in synch with one another and very quickly re-attuned to each another.
"When they re-engage with other another they actually repaired the interaction."
Tronick defines 'self-regulation' as a person's ability to control their physiology and emotions in the face of some form of stress.
When the babies were dysregulated by their mother's still face, they usually tried to keep themselves under emotional control but over time their capacity to regulate themselves wore thin.
"They use up the resource for doing that. They use up their regulatory capacities, they become distressed and they become disorganised and they're not able to put themselves back together again."
By supporting and calming a child, parents help them to gradually develop the inner resources to regulate themselves, Dr Tronick says.
"The infant is part of a system and the other part of the system is the parent or the carer. And the carer provides resources for the infant that the infant is not able to provide for themselves."
On the parents' side, a new baby provides a really wonderful opportunity to change how you are in the world, he says.
"Being with a new baby, really relating to a new baby, demands that you be open to the experience of what the baby is like and allow yourself to adjust and change to the baby.
"Despite all the crying and stress and sleep fatigue, the baby brings all sorts of positive emotions into the relationship.
"That is a really special period of time and perfect to help parents help infants and also an opportunity for them to reorganise and change themselves.
"With the birth of a new baby and their early development you're in a very messy, very disorganised period of time but what comes out of the messiness … is that you can create something new out of the messiness. When you make the adjustment to the infant you're beginning to figure out some new way of interacting with them. It also gives you new emotions and new feelings that you can have about yourself and about the infant."
The parent-child relationships with the most predictable dynamics often the most problematic, Dr Tronick says.
"If you would see infant and mother always doing the same thing, always having the same kind of interchanges with each other, often those are negative.
"There was in some sense very little messiness, very little non-contingency, in the interaction, whereas the good interactions are ones that have messiness, it gets resolved and then the [relationship] moves into the positive domain."
In intimate adult relationships, messiness isn't a bad sign either, Dr Tronick says.
Adult facial expressions last from a third to half a second and we're picking them up all the time.
Moments in which our emotions don't match another person's are inevitable and unavoidable, and the important part is to get back into synch, he says.
"When you're mismatching … you feel stressed, you feel annoyed with the other person, but when you repair the mismatch your negative emotions get transformed into positive."
Couples stuck in a pattern often perform a repetitive "dance" of negativity, Dr Tronick says: "Two individuals interact in a really stereotypic negative way - one makes the argument, the other one reacts back, the other one has the same reaction they had yesterday to what happened."
A less fixed way of relating is healthier, he says.
"In relationships which have a certain messiness about them you're always creating something new, you're always finding something new to be doing with this person."
When Dr Tronick dances with his wife they are sometimes briefly in synch, he says, but more often out of time with each other.
"But when we resolve that we trust each other, we feel really connected … I feel really excited about it."
Dr Ed Tronick is a developmental neuroscientist, clinical psychologist and the co-founder of the Child Development Unit at Boston Children's Hospital and the Touchpoints program. He is a distinguished professor of psychology and director of the Infant-Parent Mental Health program at the University of Massachusetts Boston and a research associate in newborn medicine at Harvard Medical School.