Though the Beatles confidently tell us that 'all you need is love,' behavioral psychologists were skeptical that people and animals need--or are motivated by--anything other than food, water, shelter and sex. Psychologists Harry and Margaret Harlow decided to determine scientifically whether love is something we really need or just a feeling that we have toward things that satisfy our more basic, concrete, physical needs.
Harry Harlow founded a primate lab and started studying how infant monkeys developed when separated at birth from their mothers. He put these lonely monkeys in cages with two dolls. One was made out of wire with a wooden head and contained a bottle for the monkey's nourishment. The other was made of soft foam and covered in cuddly cloth but did not have a bottle. With this setup, Harlow attempted to separate the two things the monkey gets from its mother: nourishment and comfort. The wire mother gave food, while the cloth mother gave warmth and comfort.
The prevailing behaviorist theories of the time would predict that the lonely monkey would quickly grow attached to the wire mother, since it dispensed the food. But Harlow was surprised to observe that the monkeys spent an overwhelming amount of time with the cloth mother, moving to the wire mother only when they needed to eat. Their affection for the cloth mother had nothing to do with food and everything to do with warmth and comfort.
To further test the monkeys' attachment to the cloth mother, Harlow decided to scare them to see how they'd react. He created an ugly, scary paper monster to surprise and frighten them. When the monster appeared, the monkeys screeched and cried and ran immediately to the cloth mother for comfort and security. For all measurable purposes,...