Beyond Letters: A Developmental Study of Multi-Element Processing Across Visual Categories

The multi-element processing (MEP) task measures how individuals visually encode a brief presentation of a string of elements (e.g., letters, numbers, or symbols). There are currently a range of conflicting findings regarding the core mechanism that influences MEP task performance. Previous studies have purported that poor readers struggle to perform well on the MEP task due to a visual attention span (VAS) deficit; however, others have challenged these findings instead citing a letter-sound mapping deficit. These contrasting findings may be the result of experimental differences wherein certain studies have letters (which are verbally re-coded) while others have not. In order to investigate the true deficit underlying poor performance in the MEP task, we administered a partial-report version of the MEP task using both nameable elements (letters, numbers, and objects) and unnameable elements (pseudo-fonts) to 98 children (age range: 5-17 yrs) and 23 adults (age range: 20-34 yrs). Regardless of element type, adults displayed higher MEP task performance than children. Further investigation of the serial position function (SPF), which shows task performance at each position within the string, showed no differences in each element’s SPF shape between children and adults. We also found that MEP task performance was significantly correlated with reading ability for all element types. Interestingly, children in the Control (n = 61) and Dyslexia (n = 37) groups, showed no difference in the shape of SPF. These findings indicate that MEP task performance is influenced by visual processing abilities; therefore, any difference in performance found in poor readers are element-general, and not letter-specific.