The effect of emotion on false memories in the Deese-Roediger-McDermott (DRM) paradigm

Abstract

Over the past two decades, researchers have shown that human memory is not as accurate as we would like to believe. Sometimes we recall the gist of a particular event, but the details of that event are incorrect and sometimes we report entirely false memories for an event that never occurred. On many occasions, our false memories are of little significance, but sometimes they can have dire consequences, particularly if those false memories are reported in court. Given these consequences, it is important to understand the conditions under which memory errors are most likely to occur. The most widely-used procedure to investigate false memories in the laboratory is the Deese-Roediger-McDermott (DRM) paradigm; in this paradigm, participants who study lists of words (e.g., bed, rest, pillow) in which each word on the list is related to a critical lure (e.g., sleep) often report having seen that critical lure even though it did not appear on the original list. In fact, the false recognition rate of critical lures is nearly as high as the correct recognition rate of studied words.

In many cases in which false memories really matter (e.g., eyewitness testimony or traumatic memories), the memories themselves are emotionally charged and are retrieved in a distinctive emotional context (mood). The overarching goal of my PhD research was to use the DRM procedure to investigate the effects of emotion on true and false memories in both children and adults, and to explore methods that might be used to reduce emotional false memories in laboratory settings. The first step in the research was to compile pure emotional DRM word lists in which all of the list words were semantically-related to the corresponding critical lure, and the list words and the critical lure share the same emotional valence (Chapter 4). The next step was to compare the magnitude of false memory produced by the new lists with the magnitude of false memory produced by hybrid emotional word lists used in previous research, and then to explore the effect of emotional content (i.e., new emotional word lists) on false recall (Chapter 5). To assess the effect of both emotional content and emotional state (i.e., mood) on false memory, I then used mood induction procedures to elicit a particular mood and asked participants to learn the new emotional DRM word lists (Chapter 6). In Chapter 7, I tested different theoretical predictions regarding the effect of participants’ mood on age-related increases in DRM false memories for emotional word lists. In the last two empirical chapters, I assessed whether warnings about the false memory phenomenon would reduce adults’ emotional false memories (Chapter 8), and whether directed-forgetting cues would reduce children’s emotional false memories (Chapter 9).

Generally, I found that 1) pure emotional lists generated more true recognition but less false recognition, compared to the hybrid emotional lists; 2) false memories were higher for negative word lists than for positive or neutral word lists, regardless of the type of memory test; 3) there was a negative mood-congruent false memory effect; 4) the age-related increase in false memories was eliminated in positive moods, whereas this increase was maintained in negative moods for negative information; 5) warnings had no impact on true recognition, but could reduce false recognition, no matter whether warnings were presented before study, or after study but before test; 6) directed forgetting reduced only children’s true memory, but it did not influence either children’ or adults’ false memory. I also found that no single theory could account for all of these findings. In some cases, associative theories (i.e., Implicit Associative Response Theory, Spreading Activation Theory, Associative Activation Theory, and Activation-Monitoring Theory) provide the most suitable explanation for the findings, in some cases, Fuzzy-Trace Theory (FTT) is better and in other cases, both associative theories and FTT account for the findings. Taken together, the present findings not only have important theoretical implications for understanding the development of emotional false memories, but also have practical implications for understanding the formation of adults’ and children’s emotional false memories in forensic settings.