SENSITIVITY TO VIOLATIONS OF RUN AND TRILL STRUCTURES IN RAT SERIAL-PATTERN LEARNING

Rats learned serial patterns composed of either ''run'' chunks (e.g., 123 234...) or ''trill'' chunks (e.g., 121 232...). For each type of p attern, 1 group of rats encountered an element at the end of the patte rn that violated the run or trill structure. In both run and trill pat terns, violations were unusually difficult for rats to learn, whereas corresponding elements in ''perfect'' patterns that did not violate pa ttern structure were easy. Additionally, rats' errors on violation ele ments conformed to the structure of the patterns in which they were em bedded. Thus, rats were sensitive to the run or trill organization of their patterns and mastered the rules governing the pattern before lea rning ''exceptions to the rule.''