In this experiment, we examine the behavior of the learner when the input contains error. The learner is given the same 22 noun-pairs from experiment 1 and an incorrect plural form cat[z].
The incorrect form is found not to affect the acquisition of the correct phonological constraints. The learner acquires the same 5 rule-classifiers as in experiment 1. An additional rule-classifier is created to account for the incorrect cat[z]:
6. [dc.[-tense,-strident],t,z]