Concrete thinking is a problem associated with various psychiatric disorders such as schizophrenia. It is defined as inability to think in abstract terms. Abstractions and symbols are interpreted superficially without fact, finesse or any awareness of nuance. The person is unable to free himself from what the words literally means. In the process, excludes more abstract ideas.
In addition to schizophrenia, concrete thinking can be seen in coarse brain disorders and learning disability.
This can be tested using proverbs. Person with concrete thinking would not be able to perform proverb testing tasks. However, testing should be done carefully, because people with poor educational background will not be able to perform proverb testing which results in a wrong impression.
However, concrete thinking in schizophrenia can be diagnosed easily because of other symptoms of it. In addition, concrete thinking seen in schizophrenia is incorporated into the diagnostic guidelines as part of formal thought disorder. But the weight given to it in practice is much less and usually schizophrenia should be diagnosed by other psychiatric symptoms of schizophrenia.
Symptoms of mind by Andrew sims