People addicted to watching pornography on the internet are in danger of suffering from short-term memory loss, researchers say.

German scientists studied the part of the brain responsible for keeping information in the mind while using it to complete a task, critical for understanding, reasoning, problem solving and decision making.

In the first research of its kind, they asked 28 men - all heterosexual with an average age of 26 - to look at a number of computer images, some pornographic and some nonsexual.

The clean images included pictures of people doing a number of activities, like laughing, playing sports or carrying a weapon.

As the volunteers viewed the pictures, they touched a "yes" or "no" key to indicate whether the picture was the same as one they had seen four slides previously.

The men logged a significantly greater number of incorrect answers when they viewed the porn than when they saw the nonsexual images.

On an average, they answered correctly 67 percent of the time when they viewed pornographic pictures, which rose to 80 percent when they saw the clean pictures.

According to researchers at the University of Duisburg-Essen, the findings could help psychologists understand why some people with internet porn addictions forget to sleep, miss appointments, shirk job responsibilities and neglect relationships.

"Sexual arousal and its impacts on cognitive processes might explain parts of these negative effects," the Daily Mail quoted the researchers as writing.

The study has been published in the Journal of Sex Research.