‘Only connect,” the British novelist E.M. Forster famously wrote in 1910, encapsulating in two words the core human need to bond with and relate to others at every stage of life. He did not know then that in the century that followed, massive amounts of interdisciplinary research would back up the scientific truth behind the simple-sounding motto he coined. “Only attach” might even serve as the briefest precis possible of the field now known as attachment theory.

It is one of the most influential concepts today in developmental psychology, but when it comes to parenting, it has also become one of the most misunderstood. That’s mostly due to the controversial “attachment parenting” method propounded by pediatrician William Sears and his wife, Martha, in their best-selling “The Baby Book.” Its fans are legion, and so are its critics.

One naysayer was author and new mother Bethany Saltman. The more she read, the more disaffected she became with what she viewed as the book’s over-the-top insistence on nonstop baby-centric care. The goal of attachment rang true to her, but the nature of the bond itself seemed to get lost in all the rules. Frustrated but intrigued, she set out on a years-long quest in pursuit of the ideas, applications and implications that animate attachment theory, and delved into the myriad ways the earliest parent-baby connection can affect the pathways of human development throughout life. The result is her absorbing and edifying corrective, “Strange Situation: A Mother’s Journey Into the Science of Attachment.”

Saltman tells two separate stories here: One is her personal journey as a mother, the other the story of the science of attachment. But the narratives are also deeply intertwined. How could it be otherwise when her drive to understand attachment is fueled by her desire to settle her doubts about her maternal instincts and capabilities? Even the fact that her daughter, Azalea, is growing up well-adjusted and happy can’t stop Saltman from constantly second-guessing herself. She also agonizes over her own upbringing, wondering if she is unconsciously repeating the errors she perceives in her mother’s caregiving. All these worries carry echoes of the ingrained but unreachable, perfectionistic standards of motherhood so many of us carry. But Saltman’s refrain of self-reproach can grow tedious, as can her tendency to invoke Zen philosophy.

By contrast, her research enlivens her. She becomes enthralled with Mary Ainsworth (1913-1999), the pioneering child-development psychologist who helped formulate attachment theory, and whose landmark Strange Situation experiment provides the title for Saltman’s book. Early in her career, in the 1950s, Ainsworth collaborated with the renowned psychologist John Bowlby (1907-1999) on a study of the adverse impact on young children of the death or loss of their primary (usually maternal) caregiver. This was the start of what would become Bowlby’s lifelong research focus and would in time lead to his three-volume masterpiece, “Attachment and Loss.”

For the rest of their lives, Ainsworth and Bowlby would maintain a collegial friendship and correspondence, sharing their ideas and helping refine each other’s insights about the nature of attachment. Both were also influenced by the work of ethologist Konrad Lorenz. He had observed that in some bird species, newly hatched offspring would become “imprinted” by and immediately bond with whatever they saw first — typically, their primary caregiver, their mother. Lorenz further noted what he believed were instinctual attachment behaviors. These most notably included the offspring routinely following the mother around, and the constant exchange of calls and responses between babies and mothers to ensure they remained in close contact with each other and out of danger. The similarity to patterns of mother-child attachment in humans was inescapable.

These thoughts remained with Ainsworth when she accompanied her husband to Kampala, Uganda, in 1954. There, with the help of an interpreter, Ainsworth went about befriending, interviewing and observing a number of young mothers as they cared for their babies. Her detailed notes were both expansive and extensive, and her chief finding was the solid connection between a secure maternal-infant attachment and the child’s robust physical and cognitive development.

By the time she published her findings in her book “Infancy in Uganda” in 1967, Ainsworth had joined the faculty of Johns Hopkins University. That is where she designed and introduced the Strange Situation experiment. It unfolds as a series of carefully choreographed and observed interactions between a mother and her baby — and a “stranger” who over the course of approximately 21 minutes enters and exits, creating different scenarios for the baby to react to: alone with her mother; alone with the stranger; simply alone; and no longer alone, reunited with her mother. On the other side of the one-way mirror, trained observers of these scenes of connection, separation and reunion note the emotional impact on both baby and mother of each scenario. Does the baby cry in distress when the mother leaves? Is the baby easily comforted by her mother when she returns? Are the mother and baby in sync — or not — with each other’s responses? Does the baby keep crying, perhaps even rejecting the mother, when she returns?

Ainsworth’s key finding was that the more sensitive and responsive the mother was to the baby’s needs, the more securely attached the baby would be. In what Ainsworth termed a “secure attachment,” the mother would be the secure base from which the growing child could begin to explore the world as an independent being.

The good news was that the great majority of the mother-baby pairings — about 70 percent — fell into this category of secure attachment. The other mothers were either inconsistent in or unresponsive to meeting their babies’ needs, signs of distress or attempts to engage in play. These responses Ainsworth categorized as “insecure attachment.” Subsequent research has shown an association between the array of insecure attachment styles Ainsworth observed (and meticulously described and classified) and the risk for social, psychological and relationship difficulties down the line. Today, clinicians still use this experiment, as well as the more recently developed Adult Attachment Interview (AAI), as part of their assessment and therapeutic tool kits. In addition, programs based on attachment theory are now used to enhance parenting skills in low-income families and to help mothers at risk of losing their children to foster care.

Saltman energizes her account of Ainsworth’s studies by including her own experiences in learning to administer and assess both the Strange Situation experiment and the AAI. She also undergoes the AAI — and persuades her mother to do the same. Despite her nervous anticipation of what the results will reveal, in a nice twist, they affirm that, despite Saltman’s anxieties, she and her mother have been more firmly and finely attuned to each other throughout their lives than she had recognized. Their newfound closeness might even be described as an example of attachment theory as a successful catalyst for family healing.

Saltman is at her best in her chapters on Ainsworth and the development of attachment theory. Yet she can go overboard in her identification with Ainsworth, venerating her as an idealized mentor and mother figure. She also hypothesizes, without any evidence, that had Ainsworth been able to bear and raise children of her own, she would not have chosen to pursue attachment research. “I doubt she would have had the heart to look so closely into the workings of maternal love,” Saltman writes. Huh? To my mind, this is an attachment gone too far. Fortunately, for the most part Saltman remains securely attached to her material and to the science itself. Of that, Ainsworth would have surely approved.

Strange Situation

A Mother's Journey Into the Science of Attachment

By Bethany Saltman

362 pp. $27