Transient phonemic codes and immunity to proactive interference.

Empirical data indicate that when memory for subspan lists of taxonomically related material is tested immediately after study, prior experience with lists involving the same material has no effect upon recall or recognition. In six experiments, we explored the possibility that immunity to proactive interference (PI) is related to discriminative information that is provided by transient phonemic codes. In these experiments, we manipulated the strength of phonemic codes as well as their presence or absence. Immunity to PI was found only when it was presumed that a phonemic representation of the target items existed and that information provided discriminative information. In all other cases, PI was observed. The finding that PI effects correspond with the manipulation of phonemic information in a principled fashion provides strong evidence for the role of phonemic codes in producing short-term PI effects.