The Eysencks suggested that sociopaths and criminals are high on psychoticism and schizophrenics are the highest of all. Accordingly, the Eysencks built their Psychoticism Scale primarily around aspects of personality often found in sociopaths and criminals. Nielsen and Petersen developed a scale of schizophrenism, which they defined as a subschizophrenic trait indexed by withdrawal and cognitive peculiarities. Venables et al. needed a schizotypy scale for a research project in Mauritius and found that none of the previously published scales quite met their needs. They wanted a scale to measure positive and negative symptoms of schizotypy, types of symptoms that they believed might correspond to positive and negative schizophrenia. A number of researchers have investigated the usefulness of various Minnesota Multiphasic Personality Inventory (MMPI) scales and indicators for the detection of schizotypy. Schizoidia is the underlying syndrome that gives rise to schizotypal symptoms.