Defects in reversal of serial order of symbols

Many patients with aphasia or an organic mental syndrome who can spell a five-letter word or recite a five-digit number forward fail to do so backwards. Errors also occur in reading letters of a printed word backwards whereas no errors appear in reading conventionally. Memory defects, dysnomia, dyscalculia, learning disorders, and perseveration may co-exist with an impaired ability to reverse a serial order of symbols. It would appear that a defect in the ability to reverse a serial order may be similar to defects in other faculties observed in aphasia, e.g. anomia, acalculia, and alexia. Reversability is probably a characteristic of normal cognitive function and language processes. A defect in RS of two-, three-, or four-letter words may be considered a significant sign of cerebral dysfunction due to either a localized lesion in the dominant hemisphere or a diffuse bilateral encephalopathy.