I study liars. I’ve never seen one like President Trump.

My colleagues and I found it easy to code each of our participants’ lies into just one category. This was not the case for Trump. Close to a quarter of his false statements (24 percent) served several purposes simultaneously.

Nearly two-thirds of Trump’s lies (65 percent) were self-serving. Examples included: “They’re big tax cuts — the biggest cuts in the history of our country, actually” and, about the people who came to see him on a presidential visit to Vietnam last month: “They were really lined up in the streets by the tens of thousands.”

Slightly less than 10 percent of Trump’s lies were kind ones, told to advantage, flatter or protect someone else.