Article 4 Modified Direction of DEM Test Suggests Differences in Naming and Eye Movements

Background: The Developmental Eye Movement Test (DEM) is a screening and clinical test used to evaluate ocular motility and naming skills with respect to developmental age. The DEM test combines a vertical condition to assess naming with a horizontal condition to assess naming and ocular movements. The aim of this study is to verify the assessments of naming and ocular movement in the vertical, horizontal, or combined directions. Method: The participants were 157 children in the age range from six to 14 years. Standard DEM cards (A, B, C) were used, together with a modified version, in which stimuli could be presented manipulating the crowding (the space between letters; crowded or uncrowded) and the direction (horizontal or vertical). Results: Results showed that the horizontal ocular movements are faster than the vertical, regardless of crowding between stimuli. We have also shown that the time required to execute the eye movements, which represents the best predictor of movement quality, is strongly related to the classical DEM ratio score. Conclusion: These results confirm that horizontal eye movements are faster than vertical, independent of the crowding condition. Additional information about ocular motility could be obtained by using only one direction (horizontal or vertical) and a subtractive method. Independent of these evaluations, the DEM test remains valid for clinical use because normative data permits these limitations to be bypassed.