London: It seems to be very difficult for viewers to tell the difference between real and artificially rendered 3-D films, according to new research. Examining the effects of various technologies, the researchers found that it plays virtually no role in the viewer's experience whether a 3-D film was originally produced as such or whether it was later converted from 2-D to 3-D using algorithms as, for example, is the case with new 3-D televisions. "That is surprising when you consider how much time and money goes into producing real 3-D films," said primary author of the study Andreas Baranowski from Johannes Gutenberg University Mainz (JGU) in Germany. In the study, participants were shown six short film sequences, two each from the categories horror, action, and documentary films. While there were no detectable differences when it came to the two 3-D technologies, there was divergence in the way that the three individual categories were assessed. The 108 participants of the study were given 3-D glasses and had to rate the impressions made on them by the film segments. For example, they had to say whether the story in the film drew them in, whether they were impressed by the technological aspects of the film, what type of emotion or excitement they experienced, and whether they felt any sort of queasiness due to the camera movements. They were also asked what they thought of the main characters in the films. According to the results, published in the journal Displays, 3-D films essentially inspire stronger feelings of being drawn into the story than 2-D films. However, 3-D films also more often cause slight nausea because of what can be described as 'motion sickness'. The researchers also discovered that the viewers found 3-D technology particularly interesting for action and horror films, but less for documentaries. It was of virtually no significance whether the 3-D aspect of the film was real or an algorithmic conversion, the study showed.