From complexity to distinctiveness: The effect of expertise on letter perception.

Fluent, adult readers of alphabetic languages encounter hundreds of millions of individual letters. What is the impact of such extensive experience on the perception and identification of letters? Recent evidence indicates that expert and naïve observers perceive letters differently. Here, we focus on the relationship between expertise and letter complexity (number of visual features) and distinctiveness (overlap in features with the other letters of the alphabet). Using a same-different letter judgement task, we examined the performance of individuals with high levels of expertise with Roman letters, but with different amounts of experience with the Arabic alphabet. The results reveal a trade-off between letter complexity and distinctiveness, such that while naïve individuals are sensitive only to letter complexity and not distinctiveness, the opposite is true for individuals with high expertise with an alphabet. These findings reveal a learning trajectory in which, with increasing experience, the influence of letter complexity is supplanted by distinctiveness, which requires an understanding of the relationship of each letter to the other possible letter shapes in the alphabet as a whole.