Nonlinear effect amplification: Differential susceptibility of Verbal Overshadowing as a function of time to interference

Verbalizing visual memories can interfere with later accurate recall. Whereas changes in the magnitude of this verbal overshadowing effect (VOE) as a function of delay have been reported, no study has systematically investigated multiple shorter nonimmediate delays. Does VOE happen when verbalization occurs 5-min postencoding? 10 min? 15 min? We show in a preregistered study involving 4,501 American adults randomly assigned to different timing paradigms, that the effect size of VOE at 5 or 10 min is nearly zero, with a stable and significant inhibitory effect from 15 to 20 min. We further investigate this nonlinearity in a second study of 3,174 individuals showing a distinct nonlinear “effect amplification” sometime between 12 and 14 min. This apparent critical period after stimulus onset where susceptibility to verbal interference dramatically increases may help explain potential difficulties replicating VOE. More importantly, it suggests the possibility that the 12–14 min period may represent a critical window for other interference paradigms as well.