This is something fascinating that I came across while reading the December 2003 edition of Scientific American.
The cover of the magazine features 6 photographs of the facial profile of a female model. These photographs originated from the same photo source, digitally altered with only minor differences - for example, eye/hair colour, the colour of skin. If each photo were viewed separately, one might not realise that the photos are of the same person: the ‘minor differences’ influences the viewer’s decision to classify the model into different races. In one photo the model looks perfectly Japanese, in another she looks Russian.
Reading into the feature article, I discovered that the amalgam was generated with a computer tool called the Human Race Machine, that was designed by (bioart?) artist Nancy Burson. It’s quite amazing really. Apparently, all one needs to do is to sit in front of the machine and enter a few keys, while the program does the rest of the work.
The artist’s website can be found here. It’s a pity it doesn’t contain the Scientific American photographs since they are a lot more racially ambiguous than the photos in her website.