Material-specific retroactive interference effects of the Wechsler Adult Intelligence Scale-Fourth Edition on the Wechsler Memory Scale-Fourth Edition in a nonclinical sample.

Introduction: This study investigated proactive and retroactive interference effects between the Wechsler Memory Scale-Fourth Edition (WMS-IV) using the flexible approach, and the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV).

Method: One hundred and eighty nonclinical participants were assigned to a four (visual interference, verbal interference, visual and verbal interference, vs. no interference) by two (retroactive vs. proactive) between-subjects design. The administration order of the tests was counterbalanced (i.e., administration of the WAIS-IV prior to the WMS-IV, and the WAIS-IV administered during the delay interval of the WMS-IV).

Results: The WAIS-IV produced significant retroactive interference effects on the WMS-IV; however, no proactive interference effect was observed. The retroactive interference effect was dependent on material specificity.

Conclusions: The results indicate that material presented within the delay of the WMS-IV can have a significant effect on subsequent delayed recall. Clinicians should carefully consider the effects associated with carry-over effects of these tests when using them in combination.