
The errors seem paradigmatic of rule use, hence bear on central issues in the psychology of rules: how creative rule application interacts with memorized exceptions in development, how overgeneral rules are unlearned in the absence of parental feedback, and whether cognitive processes involve explicit rules or parallel distributed processing (connectionist) networks.

Children extend regular grammatical patterns to irregular words, resulting in overregularizations like comed, often after a period of correct performance ("U-shaped development").
