Passage II

SOCIAL SCIENCE: Passage A is adapted from the article "Talk to the Hands" by Jen Doll (@2013 by The Atlantic Monthly Group). Passage B is adapted from the article "Gestures Offer Insight" by Ipke Wachsmuth (@2006 by Scientific American).

Passage A by Jen Doll

Leaving a group of friends the other night, I turned to wave. "Text me!" one of them said, waggling her thumbs in the air. I didn’t need the words to understand.

Today, we may be more likely to move our fingers across a tablet than turn the pages of a book; to swipe a card, press a button, or enter numbers onto a keypad than turn a key. We type on keyboards more often than we put pens to paper, and we roll down the windows of our cars by pressing a button instead of cranking a handle. Yet when it comes to gesturing, certain outdated motions endure.

Gestures can generally be sorted into two categories, according to Spencer Kelly, an associate professor of psychology at Colgate University. "Co-speech gestures" are the idiosyncratic, often unconscious ways we move our hands as we talk. Researchers believe these gestures help us think and speak and even learn. "Emblematic gestures" are the culturally codified motions that we use to supplement or substitute speech—the peace sign, the thumbs-up. Some of these gestures are symbolic, and some, as in the case of thumb-texting, are imitative.

As with words, we tend to pick up our hand movements from the groups with whom we communicate most frequently—especially our peers. If your friends are thumb-texting at you, you will thumb-text back at them. Soon enough, Kelly says, "the movement of your thumbs can be done without speech, and people know what it is. That’s the definition of an emblem."

Some emblems are recycled, their meanings changing as cultures evolve. Anthony Corbeill at the University of Kansas suspects that the current American connotation of the thumbs-up gesture developed during the 20th century, when GIs used the thumbs-up to signify that a plane was cleared for takeoff. Other emblems are coined afresh, the result of ubiquitous new technology or the quirks of a public figure. The fist bump, which went viral after Barack and Michelle Obama were photographed in action in 2008, can be traced to the germophobic mid-20th-century baseball player Stan Musial, who is said to have preferred it to the high five.

Passage B by Ipke Wachsmuth

The interpretations of sounds and movements are closely related. For years, the link could be demonstrated only indirectly by asking test subjects what information they gleaned from others who were speaking and gesticulating. Recent brain research has provided much better insight. For example, neuroscientist Spencer D. Kelly of Colgate University has studied gestures with the help of event-related potentials—characteristic brain waves consisting of a sequence of peaks and valleys—that occur in certain patterns when one person observes another communicating. The patterns reveal neuronal-processing steps in particular brain regions. One of the negative peaks (a valley), referred to as N400, is especially significant. It occurs when we stumble over an inappropriate and unexpected word, for example, when we hear a sentence like "He spread his toast with socks."

Kelly hooked test subjects to an electroencephalograph and charted their event-related potentials while they watched a video. In it, an actor spoke while using gestures to indicate characteristics of an object. A hand movement might fit a word semantically, such as when the word "tall" was illustrated by gesturing at a long-stem glass on a table. A gesture might also be used to convey additional information, such as when "tall" was accompanied by finger movements that indicated the thinness of the elongated stem of the glass. Viewers saw contradictory scenes, too, in which an actor combined the word "tall" with a gesture that referred to a short object on the table. And sometimes an actor made no gesture at all; in this control situation, the test subjects heard only the spoken word.

Subjects exhibited substantially different brainwave patterns depending on the situation. The researchers found strong negative peaks—a so-called N400 effect—whenever speech and gesture contradicted one another. They interpreted this phenomenon to mean that gestures and words are in fact processed together: observers factor the meaning of a gesture into their interpretation of a word.

This conclusion was supported by the finding that the event-related potentials exhibited no comparable negativity in the control situation. Even during early processing, the curves differ depending on whether the hand movement fits the word, complements it or contradicts it. "The semantic content" of hand gestures, Kelly says, "contributes to the processing of word meaning in the brain."