Capgras Syndrome

It seems interesting to note that the idea of others being inhabited by or replaced by impostors is based on an actual psychological syndrome: The Capgras Syndrome. What happens to an individual with Capgras is that they suddenly believe that their loved ones and friends (usually just focused on one in particular) are no longer themselves, and have been replaced by an imposter. Despite their loved one's exact appearance and behavior, they do not recognize them as the same person and insist that they are a fraud. The person afflicted with Capgras even recognizes that the 'imposter' looks the same and acts in familiar ways, but cannot recognize them as the person they love.
As Shelina points out in her post, one excellent interpretation of the doubles in the film replacing their originals, is that of 1950's Americans losing themselves to McCarthyism. Further, the idea of communism infiltrating American society as these pod people and living among originals as normal. This relates to the Capgras Syndrome quite well. However, it is mental illness on the side of the people who perceive these pod people to be imposters. This seems to complicate Shelina's idea that it is the people who are losing themselves to ideas like McCarthyism and Communism. Could it be that this is a comment on McCarthy himself and the people surrounding him who had the idea that Soviet spies were replacing Americans? It seems that he and his committees are the ones who are being afflicted, as Capgras affects the beholder.
With this idea, it is interesting that the Capgras Syndrome can be spread with force. Indeed, McCarthy would compel people to list suspect people. In many ways, the fact that he and the committee forced people to inform on their friends, relates to this idea of the Capgras Syndrome.