Negative mood reduces false memories for events both at encoding and retrieval

Mood affects both memory accuracy and memory distortions. The present study examined how negative, positive, and neutral mood induced either prior to learning or to retrieval affected different types of inferential false memories for everyday events. A recognition memory paradigm for photographs depicting script-like events was administered to undergraduate students (N = 145); this paradigm allows for the investigation of gap-filling and causal errors, representing respectively the likelihood of accepting new information consistent with the encoded scripts and the corresponding unseen cause (e.g., “family dinner” script: knocking over a bottle of water on the table) of a viewed action effect (e.g., pieces of a broken bottle on the floor). Further, also the subjective memory experiences accompanying false memories were examined (i.e., Remember-Familiar judgments). Participants were exposed to either negative (n = 49), positive (n = 49) or neutral (n = 47) mood through the presentation of a selection of pictures taken from the International Affective Picture System (IAPS). They were randomly assigned to a Pre-encoding condition, in which they viewed the IAPS pictures before the encoding phase of the memory task, or to a Post-encoding condition, in which they viewed the pictures before retrieval. Results showed that negative mood protected individuals against incorporation of nonpresented information regardless of time of mood induction (i.e., pre- or post-encoding), and this effect varied according to the type of error. Specifically, participants in negative mood produced fewer gap-filling errors than participants in positive mood and fewer causal errors than participants in neutral mood. Further, the negative mood group was also more accurate than the neutral group. The subjective memory experience was also affected by mood, with lower subjective recollection being associated to memory errors in the negative mood group compared to the neutral. Interestingly, both encoding and retrieval were affected, suggesting that attentional and monitoring processes could be responsible for the current findings.