Burning love, cold comfort, a prickly problem. “When we talk about our emotions, we don’t call them sightings or smellings,” says neuroscientist David J. Linden. “Relating our internal emotional state to the sense of touch is not some accident of English. Touch and emotion are inextricably linked in the brain.” His new book, Touch: The Science of Hand, Heart and Mind, is a treasure trove for anyone wanting to decode the frisson of a lover’s caress. After all, the skin, says Linden, is a social organ.

Turned On, Tuned Out
There’s a whirlwind of activity in the brain during an orgasm—the same pleasure circuit lights up when you quench your thirst, satiate your hunger, drink booze, smoke pot or take cocaine—but there’s also deactivation. The area in your brain related to fear perception shuts down, allowing you to relax. “You’re not vigilant at the moment of orgasm; you’re not worried about who’s going to come out of the back of the cave and eat you,” says Linden. Higher social cognition and reasoning centers also deactivate. “We’re not choosing the mutual funds in our retirement plans at the moment of orgasm.”

Rejection Stings
Experiencing social rejection isn’t just emotionally painful—it can hurt physically. “The phrase hurt feelings actually represents deep biological truths,” says Linden. “When someone’s feelings are hurt, that activates the same part of the brain that’s involved in emotional aspects of pain. Hurt feelings and hurt skin overlap in terms of the way they activate emotional pain circuits.” Just got dumped? Taking a Tylenol can help reduce the feeling of heartache.

Feeling It
Hold a warm mug while sizing someone up and you’ll likely perceive the person as warmer—more likable, more social. But hold a chilly iced coffee, say, and you’ll perceive the person as colder. “Warm and cold as we apply them to personality seem to overlap in our minds with warm and cold as we perceive them on the skin,” says Linden. Similarly, if a résumé is clipped to a heavy board, the applicant is evaluated as more serious and more competent than an applicant whose résumé is attached to a lightweight clipboard. Incidental sensations, it seems, color our judgments.

What does this mean for a first date? “One could speculate that meeting over a hot beverage might be in some ways preferable to meeting over icy drinks.”

Case Sensitive
Your fingertips, lips, corneas and the head of your penis are all extremely sensitive body parts, but not equally so. Corneas and genitals lack certain sensors, making them less good at distinguishing fine location. (That’s why you can feel a piece of grit in your eye but not know exactly where.) “Even though the tip of your penis is supersensitive, it is not superdiscriminative,” says Linden. “As a consequence, you couldn’t do something like read braille with it.” You could, however, read braille with your lips, which have many shallow touch receptors.

That Tickles
Why is it that tickling works only if someone does it to you? “It turns out we’re hardwired to pay less attention to sensations that result from our own motion,” says Linden. The region of the brain involved in moving your arm and fingers to tickle yourself signals the sensory part of the brain to dial down the feeling. “When someone else tickles you, there’s no reduction in that sensation.”