Communications technologies are far from equal when it comes to conveying the truth. The first study to compare honesty across a range of communications media has found that people are twice as likely to tell lies in phone conversations as they are in emails. The fact that emails are automatically recorded-and can come back to haunt (困扰)you appears to be the key to the finding. Jeff Hancock of Cornell University in Ithaca, Mew York, asked 30 students to keep a communications diary for a week. In it they noted the number of conversations or email exchanges they had lasting more than 10 minutes, and confessed to how many lies they told. Hancock then worked out the number of lies per conversation foe each medium .He found that lies made up 14 per cent of emails，21 per cent of instant messages,27 per cent of face-to-face interactions and an astonishing 37 per cent of phone calls. His results to be presented at the conference on human-computer interaction in Vienna, Austria, in April, have surprised psychologists. Some expected emailers to be the biggest liars, reasoning that because deception makes people uncomfortable, the detachment(非直接接触)of emailing would make it easier to lie. Others expected people to lie more in face-to-face exchanges because we are most practiced at that form of communication. But Hancock says it is also crucial whether a conversation is being recorded and could be reread, and whether it occurs in real time. People appear to be afraid to lie when they know the communication could later be used to hold them to account, he says. This is why fewer lies appear in email than on the phone. People are also more likely to lie in real time—in a instant message or phone call, say—than if they have time to think of a response, says Hancock. He fond many lies are spontaneous (脱口而出的)responses to an unexpected demand, such as: "Do you like my dress?" Hankcock hopes his research will help companies work out the best ways for their employees to communicate. For instance, the phone might be the best medium for sales where employees are encouraged to stretch the truth. But, given his results, work assessment where honesty is a priority, might be best done using email. Hancock's study focuses on ____________.