Bilingual witnesses are more susceptible to the misinformation effect in their less proficient language

The misinformation effect occurs when a witness views an event, is exposed to misleading post-event information, and remembers some misleading details as having occurred in the original event. The present study examined the effect of receiving post-event information and being tested in different languages on bilingual participants’ susceptibility to the misinformation effect. English-Spanish bilingual participants ( N = 234; 78% claimed English was their dominant language) watched a video, read a post-event narrative in English or in Spanish, and then were tested on details of the video in English or in Spanish. Regardless of the language in which participants read the post-event narrative, participants who were tested in English correctly recognized more true details and falsely recognized fewer misinformation details than those tested in Spanish. These results suggest that bilingual participants are more susceptible to the misinformation effect in their less proficient language, a finding that has important implications for interviewing bilingual witnesses. Even when witnesses claim to be fluent in two languages, testing their memory in their less fluent language may result in fewer true memories and more false memories.