Dissociative experience and mood-dependent memory

The prevalence of Dissociative Disorders and dissociative experiences in college populations: a meta-analysis of 98 studies

This meta-analysis of 31,905 college students includes 12 studies diagnosing Dissociative Disorders (DD) and 92 studies measuring dissociation with the Dissociative Experiences Scale (DES). Prevalence rates were used to separately test the plausibility of the Trauma Model (TM) and the Fantasy Model (FM) of dissociation. Results show 11.4% of students sampled meet criteria for DD, which is consistent with the prevalence of experiencing multiple (types of) trauma during childhood (12%), but is not consistent with the very low prevalence expected from the role of fantasy-proneness proposed in the FM. DES scores varied significantly across the 16 countries and were not higher in North America, but in countries that were comparatively unsafe. The least well-known DD was the most common, which is inconsistent with the FM which holds that the diagnosed person is enacting a familiar social role. There was no evidence that DES scores had decreased over recent decades, which does not support FM assertions that DD were a fad of the 1990s. Three of the five hypotheses tested provided clear support for the TM and a fourth hypothesis provided partial support for the TM. None of the five hypotheses tested supported the FM. The finding that DD were slightly more common in college populations than the general population did not support predictions of either model. The theoretical perspective of the authors moderated DES scores, although this is unlikely due to experimenter bias as studies led by FM theorists had significantly higher DES scores than those led by TM theorists.

Subjectivity of the Anomalous Sense of Self Is Represented in Gray Matter Volume in the Brain

The self includes complicated and heterogeneous functions. Researchers have divided the self into three distinct functions called “agency,” “ownership,” and “narrative self”. These correspond to psychiatric symptoms, behavioral characteristics and neural responses, but their relationship with brain structure is unclear. This study examined the relationship between the subjectivity of self-related malfunctions and brain structure in terms of gray matter (GM) volume in 96 healthy people. They completed a recently developed self-reported questionnaire called the Embodied Sense of Self Scale (ESSS) that measures self-related malfunctions. The ESSS has three subscales reflecting the three distinct functions of the self. We also determined the participants’ brain structures using magnetic resonance imaging (MRI) and voxel-based morphometry (VBM). Multiple regression analysis revealed a significant negative correlation between ownership malfunction and the insular cortex GM volume. A relationship with brain structure could thus only be confirmed for the ESSS “ownership” subscale. This finding suggests that distinct brain structures feel ownership and that the ESSS could partly screen for distinct brain structures.

Switch Function and Pathological Dissociation in Acute Psychiatric Inpatients

Swift switching, along with atypical ability on updating and inhibition, has been found in non-clinical dissociators. However, whether swift switching is a cognitive endophenotype that intertwines with traumatisation and pathological dissociation remains unknown. Unspecified acute psychiatric patients were recruited to verify a hypothesis that pathological dissociation is associated with swift switching and traumatisation may explain this relationship. Behavioural measures of intellectual function and three executive functions including updating, switching and inhibition were administered, together with standardised scales to evaluate pathological dissociation and traumatisation. Our results showed superior control ability on switching and updating in inpatients who displayed more symptoms of pathological dissociation. When all three executive functions were entered as predictors, in addition to intellectual quotient and demographic variables to regress upon pathological dissociation, switching rather than updating remained the significant predictor. Importantly, the relationship between pathological dissociation and switching became non-significant when the effect of childhood trauma were controlled. The results support a trauma-related switching hypothesis which postulates swift switching as a cognitive endophenotype of pathological dissociation; traumatisation in childhood may explain the importance of swift switching.

Sad people are more accurate at face recognition than happy people

Mood has varied effects on cognitive performance including the accuracy of face recognition (Lundh & Ost, 1996). Three experiments are presented here that explored face recognition abilities in mood-induced participants. Experiment 1 demonstrated that happy-induced participants are less accurate and have a more conservative response bias than sad-induced participants in a face recognition task. Using a remember/know/guess procedure, Experiment 2 showed that sad-induced participants had more conscious recollections of faces than happy-induced participants. Additionally, sad-induced participants could recognise all faces accurately, whereas, happy- and neutral-induced participants recognised happy faces more accurately than sad faces. In Experiment 3, these effects were not observed when participants intentionally learnt the faces, rather than incidentally learnt the faces. It is suggested that happy-induced participants do not process faces as elaborately as sad-induced participants.