Studies show most of the lies are motivated either by your emotion or that of the receiver.
The cognitive and Emotional cause of lie as explained in Joseph Gaspar of Rutgers University and Maurice Schweitzer of the Univeristy of Rennysylvania Wharton school‘s ‘Emotion Deception Model‘: An emotion leads us to lie and we also feel an emotion after a lie.
An Envy caused by upwards ‘Upward Social Comparison’ i.e seeing someone better than you, could lead you into lie. When you are jealous of someone’s success. For instance, a friend talk to you about an achievement; if you are the jealous type, an emotion can prompt you to say ‘I did the same,’ whereas you lied. This is beyond intentional, it’s emotion.
You can also be urged to lie by the emotion displayed by the person you are talking to.
The feeling you think you would acquire after a lie can also trigger you to speak lie. For instance, you are in the middle of trouble of which your only chance to be happy for the rest of the day is to lie.