The Effect of Orthographic Neighborhood Size on the Extent of Priming

A balance between efficient and accurate reading may be achieved by having tighter coding for words with high neighborhood densities (N) (where many words can be formed by changing one letter in the target word) and looser coding for low N words. Masked priming paradigms in adults (Castles, 1999; Forster et al., 1987) have shown facilitation on lexical decision tasks when low N word targets are preceded by form primes (e.g., ebey-OBEY), but form priming is not seen for high N targets. This finding suggests competition between orthographic neighbors and the target. In contrast, children up to grade 6 showed form priming for low N (i.e., \u3c 4 neighbors) and high N (i.e., \u3e 4 neighbors) words (Castles, 1999). However, it is unclear whether comparable form priming for high and low N words in children resulted from children not knowing the high N words’ neighbors (i.e., whether the high N stimuli were effectively low N in the study). This study used targets with very high N (i.e., \u3e 10 neighbors), assessed children’s knowledge for orthographic neighbors, and tested the developmental trajectory of form priming for low N (i.e., 0 neighbors) and high N (i.e., \u3e 10 neighbors) stimuli using a masked priming, lexical decision paradigm with children (8-12 years), adolescents (13-17 years), and adults (18-23 years). Post-experiment testing indicated that children knew approximately 9.6 of the neighbors for high N words, confirming that these stimuli were high N for children. When primed with a form prime, adults, adolescents, and children showed facilitation for the low N word targets. Children also showed facilitation for the high N targets, whereas adolescents showed non-significant inhibition and adults showed inhibition trending towards significance. The developmental trajectory in high N form priming was approximated using a cubic function, reaching adult-like levels around the age of thirteen. Thus, developmental differences in high N form priming are not the result of smaller effective N in children, ORTHOGRAPHIC NEIGHBORHOOD SIZE 3 suggesting a possible developmental change in how orthographic neighbors of a target word inhibit the target or compete with the target during lexical decision