Why are some people very aloof and unattached in their relationships, while others are clingy and need constant validation? According to attachment theory, it's because different people have different attachment styles.

Here's everything you need to know about the four attachment styles, how they're formed in childhood, and how to develop a secure attachment style.

An attachment style is a specific pattern of behavior in and around relationships. There are four adult attachment styles: secure attachment, anxious attachment, avoidant attachment, and fearful-avoidant (aka disorganized) attachment.

According to attachment theory, first developed by psychologist Mary Ainsworth and psychiatrist John Bowlby in the 1950s, a person's attachment style is shaped and developed in early childhood in response to their relationships with their earliest caregivers. Essentially, our adult attachment style is thought to mirror the dynamics we had with our caregivers as infants and children.

Attachment style includes the way we tend to respond emotionally to others, how we usually interact with partners in relationships, and how we behave when it comes to relationships in general, according to therapist Alyssa "Lia" Mancao, LCSW.

Some research measures the four attachment styles based on an individual's levels of avoidance and anxiety in relationships, as seen in the chart below.

Secure attachment style refers to the ability to form secure, loving relationships with others. A person with a secure attachment style is able to trust others and be trusted, love and accept love, and become close to others with relative ease. They're not afraid of intimacy, nor do they feel panicked when their partners need time or space away from them. They're able to depend on others without becoming totally dependent.

About 56% of adults have a secure attachment type, according to foundational attachment research by social psychologists Cindy Hazan and Phillip Shaver in the 1980s.

Secure attachment is considered the healthy ideal for relationships. All other attachment styles that are not secure are known as insecure attachment styles.

More about the secure attachment style:

Anxious attachment style is a type of insecure attachment style marked by a deep fear of abandonment. People with an anxious attachment style tend to be very insecure about their relationships, often worrying that their partner will leave them and thus always hungry for validation.

Anxious attachment is associated with "neediness" or clingy behavior in relationships, such as getting very anxious when your partner doesn't text back fast enough and constantly feeling like your partner doesn't care enough about you.

Anxious attachment is also known as anxious-preoccupied attachment, and it generally aligns with the anxious-ambivalent attachment style or anxious-resistant attachment style observed among children. Some 19% of adults have the anxious attachment type, according to Hazan and Shaver's research.

More about the anxious attachment style:

Avoidant attachment style is a type of insecure attachment style marked by a fear of intimacy. People with an avoidant attachment style tend to have trouble getting close to others or trusting others in relationships, because they ultimately don't believe their needs can get met in a relationship.

In relationships, avoidant people typically maintain some distance from their partners or are largely emotionally unavailable. They may even find relationships suffocating and avoid them completely, preferring to be independent and rely on themselves.

Avoidant attachment is also known as dismissive-avoidant attachment, and it generally aligns with the anxious-avoidant attachment style observed among children. Some 25% of adults have the avoidant attachment type, according to Hazan and Shaver.

More about the avoidant attachment style:

Fearful-avoidant attachment style is a combination of both the anxious and avoidant attachment styles. People with fearful-avoidant attachment both desperately crave affection and want to avoid it at all costs. They're reluctant to develop a close romantic relationship, yet at the same time, they feel a dire need to feel loved by others. 

Fearful-avoidant attachment is also known as disorganized attachment because the attachment behaviors displayed by these individuals can seem inconsistent and oscillate between the extremes of avoidance and anxiousness.

In general, the fearful-avoidant attachment style is relatively rare and not well-researched. But we do know it's associated with significant psychological and relational risks1, including difficulty regulating emotions, heightened sexual behavior, and increased risk for violence in their relationships.

More about the fearful-avoidant attachment style:

Below are the descriptions of the main attachment types used in Hazan and Shaver's foundational research on attachment theory. Read the statements and pick the one that most resonates with you:

Once you've picked the number you most resonate with, scroll back up to the descriptions of each attachment style in the previous section of this article. The number you picked here corresponds with your attachment style in the list up there. (Note: Fearful-avoidant attachment, the fourth and rarest attachment type, was not studied in Hazan and Shaver's research and is not included in this mini attachment quiz. The two more detailed quizzes below can tell you if this may be your attachment type.)

Here are two more attachment style quiz options to try:

RELATED: Attachment Style Quiz: A 5-Minute Test To Find Out What Your Attachment Style Is

Attachment styles are typically developed in infancy based on our relationships with our earliest caregivers. Researchers believe attachment style is formed within our first year of living, between 7 to 11 months of age, according to mental health counselor Grace Suh, LMHC, LPC. According to Mancao, it's "determined by how the primary caregiver responds to the child's cues when they are experiencing emotional stress."

"Human beings are born helpless, so we are hardwired at birth to search for and attach to a reliable caregiver for protection," Peter Lovenheim, author of The Attachment Effect, writes at mbg. "The quality of that first bond—loving and stable or inconsistent or even absent—actually shapes the developing brain, influencing us throughout life in how we deal with loss and how we behave in relationships."

Here's a quick primer on what circumstances lead to each of the four attachment types:

Caregivers are not the only ones who shape your attachment style, however. People's attachment styles may also be influenced by other significant relationships throughout their lives, such as friendships and past romantic relationships. "A person can have had a secure attachment during childhood; however, betrayals and infidelity in adulthood can lead to an insecure attachment," says Mancao. 

It's also possible to have a different attachment style in different situations, according to Mancao. "While we may have a primary attachment style, depending on our relationships, we may feel more secure with one person than we do with another," she explains. "For many people, their attachment style is not the same in every relationship they encounter. Things that contribute to this are their counterpart's (romantic or platonic) personality and feelings of safety."

RELATED: How To Tell Someone's Attachment Style On A First Date

Although often referenced as "Bowlby's attachment theory," attachment theory as we know it today was developed by several researchers over the course of the late 20th century. British psychoanalyst John Bowlby developed the concept of attachment behaviors around the 1950s. His theory was that children's tendency to emotionally attach to their caregivers and to become distressed and seek them out in their absence was an adaptive evolutionary trait, something that allowed children to survive by clinging to an attachment figure who provided support, protection, and care when they were too young to care for themselves.

Mary Ainsworth, a psychologist and one of Bowlby's colleagues, expanded on Bowlby's original attachment theory by identifying individual differences in how infants handled separations from their parents. Her famous "strange situation" experiment in 1969 identified four attachment types among infants: secure, anxious-resistant, avoidant, and disorganized.

Later in the 1980s, social psychologists Cindy Hazan and Phillip Shaver began to apply Ainsworth and Bowlby's attachment theory to adult romantic relationships, giving birth to the concept of the adult attachment styles we know today. In 1998, research psychologist Kelly Brennan and her colleagues further expanded on adult attachment, demonstrating two distinct dimensions that shape attachment patterns: attachment-related anxiety and attachment-related avoidance. People can be low in both, high in one and low in the other, or high in both, which determines their attachment style. (See above graphic.)

Today, there's some criticism of attachment theory among psychologists who say it's a stretch to believe caregivers can so dramatically shape infants' future relationships from such a young age. Indeed, thus far, studies attempting to draw a line between infant attachment patterns and their adult attachment styles have only found "small to moderate" correlations, according to Fraley himself. "Based on these kinds of studies, it seems likely that attachment styles in the child-parent domain and attachment styles in the romantic relationship domain are only moderately related at best," Fraley writes in a University of Illinois article.

But the concept of attachment styles is enduring for a reason: It gives people language to describe the distinct ways they show up in their relationships, and it challenges them to look to their past experiences to help them understand why they are the way they are.

RELATED: Ambivalent Attachment: 7 Signs, Causes + Steps To Heal

In 1969 and subsequent years, psychologist Mary Ainsworth and her colleagues ran experiments known as The Strange Situation that identified and observed attachment behaviors in children. Her team brought mothers and their infants into the lab and had them play in a room with toys on the floor and with various other adults coming in and out of the room. At some point, the mothers would get up and leave the room without their child. After a while, they'd return. The researchers wanted to observe how children responded first to their caregiver leaving and later to their caregiver returning to them.

Here are some of the patterns they observed:

Start by thinking about your relationship with your parents as a child, says Suh. She recommends asking yourself questions like:

This will help you get more clarity on what may have shaped your attachment style.

"Assess your current and past attachment style and identify if there are any patterns in choosing romantic partners," Suh says. "Be aware of your childhood history; the familiarity is comforting, whether it was good or bad. Meaning, your past unhealthy relationship patterns from childhood can recreate in adulthood."

Low self-esteem is a common characteristic across all insecure attachment styles, says Suh.

"Learn to embrace, value, love, and care for yourself first," she recommends. "If you cannot fathom what self-love is because you were neglected, abused, and dismissed as a child, you can start with self-tolerance and self-neutrality. This can look like, 'I'm a person, and everyone deserves to be valued' instead of forcing yourself with empty words of, 'I'm beautiful and valuable.'" 

(Here's more on learning to love yourself, plus how to raise your self-esteem after a breakup specifically.)

At the end of the day, all insecure attachment styles are people who tend to form insecure relationships because of deeply held fears that their relationships will not work out. So it's important to figure out how to make yourself feel more secure in your relationships. Part of that involves being aware of what your needs and desires are in relationships. 

"Learn to be assertive and set boundaries. Honor what you feel, and express your needs in words without manipulation and hidden meanings," Suh says. "Securely attached people are often direct and appropriately confrontational to create a healthy and meaningful relationship."

"Therapy is helpful, both individual and couples," Suh says. "A quality therapist will help you to dive into your attachment style, past wounds, ways to identify, establish appropriate boundaries, and promote a healthy relationship."