Assessing beliefs about 'environmental illness/multiple chemical sensitivity'

Knowledge representation was used to characterize beliefs in patients with Environmental Illness/Multiple Chemical Sensitivity (EI/MCS). EI/MCS patients, allergy and asthma patients, doctors and controls made relatedness judgments on concepts relevant to EI/MCS. Associative networks showed that EI/MCS patients viewed these concepts differently from others. Multiple chemical exposure was central in EI/MCS networks, with many links to every other concept, but was only peripherally connected in the other subject networks. Similarity comparisons to an EI/MCS prototype network discriminated EI/MCS patients from the other control populations, as did an index based on critical concept pairs. This approach shows promise for distinguishing patient groups using belief structure.