That’s according to Eric Rassin and colleagues who asked students to imagine a battle scene from either the Second World
War or from Medieval times. Students who imagined a Medieval scene rated their own imagery as more vivid than those who imagined a Second World War scene. And students whose Second World War imagery was less vivid agreed more strongly with the suggestion that history books exaggerate Nazi atrocities.
“…perhaps people may conclude that a particular event cannot have taken place because they are unable to imagine it”, the authors speculated. “[And this] activation of unclear mental imagery may foster readiness to deny Nazi cruelties”, they continued. In which case, “…next to political reasons there may also be a cognitive reason for Nazi cruelty denial”.
"...for educational purposes it would be better to show people modern films like Saving Private Ryan..."
Rassin, E. & van Rootselaar, A-F. (2005). Nazi cruelties: are they literally hard to imagine? British Journal of Psychology, 96, 321-329.