Editor’s Note: This is the third part in a four-part series on attraction.

Whether a person is single, complicated, seeing someone, married, engaged, going steady, dating or divorced, attraction plays a vital role in society. Although each couple’s story is unique, there actually are a few stages and signposts that psychologists have identified in the progression of love.

Lust

“[When I met my boyfriend,] there were definitely some butterflies; I thought he was cute, but I didn’t really know him,” said Kristin Heise, junior in architecture, of her boyfriend, Trey Mason, junior in management information systems.

Kristin’s experience aligns perfectly with the first stage in love – lust. Defined by University of California-Berkley psychologists as an intense desire, lust is usually based upon physical characteristics or assumptions built on observation. Driven by testosterone or estrogen, this stage begins “at first sight,” and only later progresses to the next stage of love.

Attraction

Lust has the potential to deepen into a state of attraction.

“After I got to know Trey, I realized I really liked him and I needed to trust him,” Heise said.

During this stage, sometimes referred to as “puppy love,” there are intense feelings of physical and emotional attachment. The brain releases a series of chemicals, known as monoamines, which include dopamine, norepinephrine and serotonin. Interestingly enough, dopamine is also activated by cocaine and nicotine, causing feelings of addiction and desire. Norepinephrine, commonly known as adrenaline, is responsible for an increased heart rate, sweating palms, shaking hands, and yes, even going weak at the knees. Finally, serotonin boosts feelings of happiness and pleasure. A loss of appetite, need for less sleep and increased energy level also accompany this chemical release.

“When I’m with Kristin, I never want to be anywhere else,” Mason said.

While these chemicals can continue for months at a time, eventually the experience of attraction reaches a critical breaking point. The stimulus, namely the person of attraction, becomes familiar and no longer has the desired effect. One must either move on to the final stage of love, or like so many relationships, go back to the drawing board.

Attachment

The final stage of love, known as attachment, can last for an indefinite period of time. This final stage usually allows couples to stay together for long spans of time and through difficult circumstances.

In attachment, two key chemicals are released in the brain. The first chemical, oxytocin, is released prevalently in only two stages of human development. Initially released during child birth, it accompanies breast milk to cement the bond between mother and child. Later in life, it is released during sexual intercourse, creating a strong psychological bond.

A second chemical, vasopressin, accompanies oxytocin in creating consistent and enduring unity with one’s partner.

These chemicals, along with those released during the attraction stage of love, are magnified with the first experience of sex or love, according an article by the British Broadcasting Corp.

Hence, with each subsequent sexual experience or deep emotional relationship, the power of such bonding chemicals is reduced.

More information on the three stages of love is available at www.bbc.co.uk/science/hottopics/love/.