Memory Distortion via Imagination: Neural Correlates and Forensic Applications

Our memory is vulnerable to changes so that the way we remember past events can become distorted over time. One way that memory distortions may occur is if we rehearse and imagine an alternative scenario to what really happened. Such counterfactual imagination may distort the true memory and create a false memory of the imagined event. This has crucial implications, especially in forensic settings because guilty suspects may adopt this technique as a countermeasure, in an attempt to evade blame. The research presented in this thesis investigated the effect of counterfactual imagination on memory detection tests—the Autobiographic Implicit Association Test (aIAT) and the Concealed Information Test (CIT)—using both behavioural measures and EEG methods. It also investigated the neurocognitive mechanisms underlying counterfactual imagination effects on memory, and whether counterfactual imagination actually impairs the true memory of the original event. Results from five experiments supported the view that counterfactual imagination can distort our memory, leading to significant effects on forensic memory detection in some circumstances and with some types of tests. Specifically, it was found that the aIAT is very susceptible to the effects of counterfactual imagination, while the CIT is more resistant to this countermeasure. Furthermore, I found that counterfactual imagination impaired both recall and recognition of true actions, and I describe novel EEG effects that were associated with counterfactual imagination and subsequent memory impairments, thus providing new evidence of the neurocognitive mechanisms that underlie counterfactual imagination effects on memory. Altogether, my research makes an original contribution to improve our understanding of counterfactual imagination and memory distortion and suggests that forensic memory detection tests should be used with caution.