Research

I found a different study online, this one was actually free to access. In the introduction it says that although several independant studies have confirmed the cross-race effect, other studies have lead to different results. They claim that there are a number of possible reasons for this including the type of stimulus used, the encoding time and the delay between study and test. This lead to a number of questions for me, the most important being that I had thought that the study and test were the same thing. But obviously they're not. So, what's the difference?
Well apparently this sort of experiment is made up of two main stages, not one. I'd intended to just show the pictures of models to my volunteers and ask "have I shown you this face before?" all in one go, but this isn't how it's done. Instead the first stage is the study where faces are shown to the volunteers for a set amount of time (in this study it was 3 seconds with an interstimulus time of 1.5 seconds). During the study the volunteers aren't asked any questions about the faces, just told to remember the faces. The next stage is the actual test. The volunteers are shown faces and asked questions (in this study they were asked if they had been shown the faces before and just had to give a yes/no answer. There was no time limit, the picture remained until they had answered.) This method of performing the experiment, with both a study and test, makes a lot more sense. It's rather exciting, I feel like I'm a considerable way closer to performing my SRP.
The report also confused me with mention of an "encoding time". When I first read this phrase I had no idea what it meant, however I think, it refers to how long each image is shown in the study.
Another question the introduction raised for me was "is there more than one type of possible stimulus?" I'd thought not, you could only show pictures (or maybe computer-generated faces). However after reading their method, I think what they mean is the type/quality of picture instead of completely different types of stimulus. For example they go into a lot a detail about the picture: the background was digitally removed, the colour resolution and pixels of the images remained the same the light in the image was fixed etc.
During the discussion of this report, which was titled "Recognizing faces across continents: The effect of within-race variations on the own-race bias in face recognition" the authors suggested another reason that different studies have found varying results. It is because the definition of race in these cross-race effect experiments is rarely given. For example if the races being studied were termed black and white, it would be assumed that white South Africans would be able to distinguish the faces of white Americans as well as other white South African faces, and that they would find black American faces just as hard to distinguish as black South African faces. But this is not always the case. Their conclusion was that own-race bias (another term for cross-race effect) should be "retired from literature" as race cannot be defined with precision and this can result in false conclusions. Basically, they've said me whole experiment is pointless. Ah well, I still find it interesting.
NB. In case anyone's interested, the website where I found all this is http://works.bepress.com/cgi/viewcontent.cgi?article=1039&context=christian=meissner