
Management guru Peter Drucker once said that the most important thing in communication is to hear what isn't being said. Although the exact figures aren’t agreed upon, most researchers agree that what we say (verbal communication) alone makes up less than 10% of our message, with the receiver taking the rest from non-verbal cues. These cues include kinesics(body language),paralinguistics(vocal nonverbal cues), chronemics(time conveying meaning), objectics(physical objects), oculesics(eye contact), haptics(touch), and proxemics(space and distance).
Sue Shellenbarger recently posted an article on the Wall Street Journal website, titled “For Teens, Has Texting Replaced Talking?” detailing how her kids spend most of their time texting. From the invention of the telegraph, to the everyday use of email and text messaging, we have introduced increasingly elaborate means of communicating with one another. However, it seems that as a result of this, we are in reality cutting down on communication. With increasing use of technology, most of our communication takes the form of the written word alone. Even in the same office, two colleagues who are seated right next to each other will be more likely to send instant messages or emails, rather than talking face-to-face. With the elimination of the interaction between two people, they are unable to observe any non-verbal cues the other may display. This eliminates much of the possible discussion that would otherwise occur. For example, a subordinate may agree with the boss because he doesn’t want to appear uncooperative, but have concerns about a scheme. With face-to-face interaction, the boss can hear the hesitation in his voice (paralingsuistic), and view his less than exuberant enthusiasm about the project (kinesics), allowing him to solicit the employee's opinion.

Our ever more reliance on technology to communicate may result in an eventual inability to interpret such nonverbal cues. We have not yet entirely substituted text messages and emails for face-to-face communication, or even split them 50-50, but in time to come such forms of communication will likely take precedence. Although Ms Shellenbarger doesn’t believe that texting affects one’s ability to read non-verbal cues, she admits that it’s annoying when people try to text and talk to you at the same time. This is in fact an example of how such people don’t realize the non-verbal cues that they’re sending; in this case, ‘I don’t care enough to concentrate on just talking to you’.
References
Sue Shellenbarger, 'Have we lost our ability to communicate?', http://blogs.wsj.com/digits/2009/09/03/for-teens-has-texting-replaced-talking/