A new experimental technique has been invented in which two different events can be presented independently to a pair of subjects sitting side-by-side in front of the same screen so as to make them believe that they are watching the same event simultaneously. Two video projectors with polarizing filters diagonal to each other projected different moving pictures on the same screen. These were observed by a pair of subjects wearing polarizing sunglasses suitable for one or the other video projector. Using this experimental technique, thirty pairs of undergraduates observed basically the same event but three nonconforming points were included. Each pair of subjects were asked to report individually on what they had seen— Pre-Discussion Report. Then they were allowed to discuss the event they had just observed, and were asked to report again— Post-Discussion Report. Subjects were invited to come to the laboratory a week later to report what they had seen the week before— Week-Later Report. Fifteen pairs of the subjects were instructed to come to agreement during the discussion whereas the other fifteen pairs were simply instructed to discuss what they had seen. In the Week-Later Report, subjects in the former group tended to change their memory of the event, either consciously or subconsciously, whereas this tendency was much less in the latter group. In general, the Post-Discussion Reports were more complete than the Pre-Discussion Reports, that is, the discussion inproved the subjects' memory of the events.