HINDSIGHT BIAS AND THE MISINFORMATION EFFECT - SEPARATING BLENDED RECOLLECTIONS FROM OTHER RECOLLECTION TYPES

Questioning the presence of ''truly'' blended recollections, we invest igated two cognitive phenomena: hindsight bias and the misinformation effect. At first glance, both phenomena seem to result from the same i nterference process, whereby the subsequent encoding of conflicting in formation impairs the recall of earlier encoded (original) material. E xperiment 1 compared both paradigms using numerical items as material: hindsight as well as misinformation subjects revealed the same mean s hift in their recollection of the original values. The additional anal ysis of a multinomial model, however, suggested that blended recollect ions occurred in the hindsight condition only. The misinformation effe ct, on the other hand, appeared to be based on averaging across two di fferent recollection types. Experiment 2 further investigated how the memory-trace strength influences the likelihood for blended recollecti ons to occur. In a misinformation procedure, one group of subjects rea d the original information twice, another group thrice. Again, recolle ctions were similarly shifted towards the misinformation in both group s. But the multinomial model revealed that only the second group (with a stronger memory representation of the original information) showed blended recollections. Taken together, these results suggested that: ( 1) a minimum memory-trace strength of the original information must be met for blended recollections to occur; and (2) hindsight bias and th e misinformation effect-though superficially similar-are induced by di fferent cognitive processes.