Strategic design of protocols to evaluate vision in research on aphasia and related disorders

Background: Most experimental and assessment tasks in studies of neurogenic language disorders rely on visual information processing. Given that many patients with such disorders have visual deficits, failure to describe and/or control for visual function may lead to invalid data collection and interpretation. A review of literature on participant description in aphasia research indicates a clear need for improvement in the description of and control for visual acuity, colour perception, visual fields, visual attention, and ocular motor functions. Few authors control for or describe even basic aspects of vision. Aims: Strategic design of visual screening protocols is advocated. Appropriate selection of screening methods depends on specific assessment and experimental tasks to be administered in a given study. Researchers are encouraged to implement, and to describe in published reports, specific procedures to address visual acuity, colour perception, visual fields, visual attention, and ocular motor functions. Main Contribution: Visual characteristics are presented within a framework of (1) those that may be evaluated as part of a case history and (2) those that may be directly screened by experimenters or assessed by collaborating professionals. Recommended screening procedures, and their relevance to various assessment and experimental tasks, are described to assist researchers in strategically designing visual assessment protocols for future studies involving individuals with aphasia and related disorders. Conclusions: Improved assessment of visual function will improve the validity, quality, and replicability of research as well as readers' interpretations of published data and authors' conclusions. Formative feedback concerning appropriate participant control and description is critical for improving the peer review process for research publication and funding. As training in visual assessment is not central to the training of most researchers in neurogenic communication disorders, further focus on this important issue within graduate programmes and continuing education curricula is needed.