The study, conducted at the University of Chicago and published in the online journal Cortext, looked at 38 people who considered themselves “very lonely” and 32 people who didn’t identify as lonely.
From there, researchers conducted something called a Stroop Test, which asks participants to focus first on the color of a word’s lettering rather than its meaning. This allows the meaning or impact of the word to be subconscious. The words fell into four categories: social and positive ( like “party”), nonsocial and negative (like “solitary”), nonsocial and positive (like “joy”) and social and negative (like “sad”).
During this test, an electrode of 128 sensors was placed on the participants’ heads to measure their brain waves for 480 milliseconds. For the first 280 milliseconds, lonely people’s brains responded in the same way to negative and nonsocial words. But after that point, their brains activated in the neural areas devoted to attention when shown socially negative words, whereas non-lonely people responded to both social and non-social negative words for the full 480 milliseconds.
In other words, lonely people focused on the negative while non-lonely people focused on everything.
Although this was a small study and more research needs to be done, researchers Stephanie and John Cacioppo and Stephen Balogh concluded that this subtle difference actually shows that lonely people’s intense response to a social threat over half a second is probably implicit.