Final answer:
The specific study by Barton et al. is not referenced, and thus details about their participants and study cannot be provided.
Step-by-step explanation:
The study by Barton et al. is not provided in the reference materials, so it is not possible to accurately state how many participants they used nor what the participants had damage to. It is important to refer to the specific study in question for such details. The provided references (Doyle, K. P., R. P. Simon, et al. 2008) and the snippets supplied are not related to Barton et al. and instead discuss different aspects of psychological and medical research.