Complex sentence: Where the original report had 42 subjects (21 in each condition), Ranehill and colleagues had 200, and the experimenters were kept unaware of which condition each subject was in to avoid experimenter bias.
Split into simpler sentences: Where the original experiment had 42 subjects (21 in each condition), Ranehill et al had 200. The experimenters were kept unaware of which condition each subject was in to avoid experimenter bias.