An experiment that changed psychology
What truly bonds a baby to its mother? Is it only the need for food… or is there something deeper?
This was the big question psychologist Harry Harlow set out to answer in the 1950s. He did so through one of the most famous—and controversial—studies in psychology: the attachment experiment with rhesus monkeys.
The results shocked the world: babies didn’t just seek food, but also affection, physical contact, and emotional security.
What Harlow’s experiment consisted of
Harlow separated infant monkeys from their mothers and placed them in a cage with two artificial figures:
- A “mother” made of wire, cold and rigid, but with a bottle of milk.
- A “mother” covered in soft cloth, without food, but warm and comforting to touch.
Logic would suggest the babies would spend more time with the wire mother that provided nourishment. But the opposite happened: the monkeys clung to the cloth mother for hours, only approaching the wire mother briefly to feed.
The conclusion was clear: attachment is not based only on food—it depends on affection, safety, and physical closeness.
The impact on attachment theory
Until then, many believed babies loved their mothers simply because they fed them. Harlow showed that view was incomplete.
His research strongly influenced John Bowlby’s attachment theory, which emphasized that early emotional bonds are the foundation of healthy psychological development. Without secure attachment, children may face greater emotional and social difficulties later in life.
Today, this idea is essential in child psychology, education, and conscious parenting.
Real-life examples of attachment
You’ve probably seen similar situations yourself:
- A baby who calms down not when fed, but when held in their caregiver’s arms.
- A child who prefers sleeping with a soft toy rather than being alone in bed.
- Even adults: after a tough day, we don’t always need “solutions,” we need a hug that makes us feel safe.
These examples show that human contact and affection are as vital as food.
Criticism and ethical dilemmas
Although Harlow’s findings were groundbreaking, they raised serious ethical concerns. The monkeys were deprived of natural maternal care, and some suffered long-term emotional damage.
Such experiments would not be allowed today, but their impact on psychology remains immense.
Why it’s still relevant today
Harlow’s lesson is not just historical—it’s something we experience every day. The need for affection and attachment runs through all human relationships:
- At work, we perform better when we feel supported.
- In romantic relationships, we don’t just seek company, but emotional safety.
- In friendships, genuine care helps us overcome hard times.
The experiment reminds us: love and human connection are basic needs, not optional extras.
Final reflection
Harry Harlow’s study left us with a profound lesson: we are not only beings who need food or success—we are beings who need affection, connection, and emotional security.
Next time you think about what truly bonds people together, remember those little monkeys: they chose the warmth of a hug over food.
👉 For a clear, visual breakdown of this experiment and its impact on our lives, check out the full video on our YouTube channel, PsyLife.
