The goal of the paper was to investigate whether morphological units -- stems and suffixes -- influence orthographic processing by modulating visual attention demands to the task. Orthographic processing was measured with a visual one-back task requiring letters to be detected within pseudowords not including stems/suffixes, or containing real stems or real suffixes. Fourth grade children (between 9.5 and 10.5 years old) who read in a transparent orthography of a morphologically rich and agglutinative language (Basque) were tested. The results showed that the presence of morphemes in the strings did not improve letter detection performance though it slightly modulated the distribution of visual attention, showing a bias toward the processing of central letters in the presence of a stem. We suggest that the presence of highly regular and recurrent structures prioritizes stem identification, which when achieved, reduces visual attention deployment across the remaining letters.