Background–Adult Attachment Theory and Research: A Brief Overview  by R. Chris Fraley:

The theory of attachment was originally developed by John Bowlby (1907 – 1990), a British psychoanalyst who was attempting to understand the intense distress experienced by infants who had been separated from their parents. Bowlby observed that separated infants would go to extraordinary lengths (e.g., crying, clinging, frantically searching) to prevent separation from their parents or to reestablish proximity to a missing parent. At the time of Bowlby’s initial writings, psychoanalytic writers held that these expressions were manifestations of immature defense mechanisms that were operating to repress emotional pain, but Bowlby noted that such expressions are common to a wide variety of mammalian species, and speculated that these behaviors may serve an evolutionary function.

Drawing on ethological theory, Bowlby postulated that these attachment behaviors, such as crying and searching, were adaptive responses to separation from a primary attachment figure–someone who provides support, protection, and care. Because human infants, like other mammalian infants, cannot feed or protect themselves, they are dependent upon the care and protection of “older and wiser” adults. Bowlby argued that, over the course of evolutionary history, infants who were able to maintain proximity to an attachment figure via attachment behaviors would be more likely to survive to a reproductive age. According to Bowlby, a motivational system, what he called the attachment behavioral system, was gradually “designed” by natural selection to regulate proximity to an attachment figure.

The attachment behavior system is an important concept in attachment theory because it provides the conceptual linkage between ethological models of human development and modern theories on emotion regulation and personality. According to Bowlby, the attachment system essentially “asks” the following fundamental question: Is the attachment figure nearby, accessible, and attentive? If the child perceives the answer to this question to be “yes,” he or she feels loved, secure, and confident, and, behaviorally, is likely to explore his or her environment, play with others, and be sociable. If, however, the child perceives the answer to this question to be “no,” the child experiences anxiety and, behaviorally, is likely to exhibit attachment behaviors ranging from simple visual searching on the low extreme to active following and vocal signaling on the other (see Figure 1). These behaviors continue until either the child is able to reestablish a desirable level of physical or psychological proximity to the attachment figure, or until the child “wears down,” as may happen in the context of a prolonged separation or loss. In such cases, Bowlby believed that young children experienced profound despair and depression.

From Attachment Styles and the Art of Self-Control | Psychology Today:

Self-control is fundamental to social life and underlies the ability to interact effectively with others. But efforts at self-control deplete the mental energy needed to keep your impulses, negative thoughts, and emotions in check. Psychological researchers call this loss of energy ego-depletion.

Each attachment style experiences ego-depletion from different sources and in different ways. Secure attachment is associated with being able to get emotional needs met directly by seeking closeness to others who are available to act as secure bases. Insecure attachment styles, on the other hand, are defensive adaptations that develop when secure bases are inconsistent, not available, or downright scary. When secure bases (e.g., parents in childhood or romantic partners in adulthood) respond inconsistently (sometimes warm and embracing; sometimes cold or rejecting), people develop anxious/preoccupied attachment styles and manage their emotions through hyperactivation of their attachment systems. Hyperactivation corresponds with high sensitivity to social cues, strong emotional reactions, and attempting to manage social perceptions.

On the opposite end of the spectrum, those with avoidant/dismissing attachment styles control their emotions through deactivation of their attachment system. Deactivation corresponds with low sensitivity to social cues, blunted emotions, and ignoring or suppressing negative social perceptions. Suppressing unwanted thoughts and memories is one of the hallmarks of dismissing attachment. If you ask a dismissing person about memories of their early childhood, for example, they will give you a very general and very positive statement (e.g., my childhood was fantastic!) devoid of specifics or actual examples. If you press them for specific memories, they are likely to respond with a statement that they have very little memory of their earlier childhoods.