dissociative identity
1. Article Summary and Analysis
Type of article
This is a systematic review of experimental research. The authors reviewed and evaluated existing experimental studies about behavioural, subjective, autonomic, and neural responses in people with depersonalisation-derealisation disorder (DDD). (p. 1)
It is not a primary empirical study because the authors did not conduct a new experiment with participants. (pp. 1–3)
Main question and purpose
The main question is: What does experimental research show about behavioural, autonomic, and brain responses in people with DDD?
The authors wanted to bring together existing research, evaluate theories about what causes DDD, and identify areas where more research is needed. (pp. 1–2)
Main findings and arguments
Some studies found that people with DDD have reduced emotional responses to unpleasant pictures and sounds. (pp. 1, 8–9)
Some brain-imaging studies found increased activity in brain areas involved in controlling emotions when participants viewed unpleasant images. (pp. 1, 9)
Findings about facial-expression recognition, emotional memory, and autonomic responses were inconsistent. (pp. 1, 7–9)
Overall, the authors suggest that changes in emotional reactions and emotion regulation may be involved in DDD, but the evidence is not strong enough to draw definite conclusions. (pp. 10–11)
Main concepts and theories
Depersonalisation: Feeling detached or separated from yourself.
Derealisation: Feeling detached from your surroundings or feeling that the world is unreal. (p. 1)
Neurobiological model: Suggests that increased activity in the prefrontal cortex may reduce activity in emotional brain regions, contributing to emotional numbness and reduced physiological responses. (pp. 1–2)
Cognitive-behavioural model: Suggests that anxiety, excessive self-monitoring, and focusing too much on DP/DR symptoms can help maintain the disorder. (p. 2)
Predictive coding/interoceptive models: Suggest that changes in how the brain processes bodily signals may contribute to feelings of disconnection from the body. (p. 2)
How the theories explain DDD
The neurobiological model explains emotional numbness as a result of increased control from the prefrontal cortex and reduced activity in emotional brain regions. (pp. 1–2)
The cognitive-behavioural model explains how paying too much attention to symptoms and interpreting them as threatening may keep symptoms going. (p. 2)
Predictive coding models suggest that reduced or altered processing of bodily signals may contribute to feelings of disconnection from the self. (p. 2)
Evidence supporting the theories
Some brain-imaging studies found increased prefrontal activity and reduced activity in areas involved in emotional processing. (pp. 9–10)
Some studies found reduced subjective emotional responses to unpleasant images and sounds. (p. 8)
One study found that directing attention away from DP/DR symptoms could temporarily reduce symptoms. (pp. 4, 9)
Other studies found changes in autonomic responses, including skin conductance and heart rate. (p. 8)
What is supported versus what still needs testing
Research supports the possibility that emotional processing and regulation are altered in DDD. (pp. 8–11)
Some studies support the neurobiological model, but the results are not consistent enough to confirm it completely. (pp. 9–11)
The exact causes of DDD and how emotional, cognitive, and physiological changes interact are still unclear. (pp. 10–11)
More research is needed to understand bodily-signal processing and self-referential processing in DDD. (pp. 10–11)
One important unanswered question
- How do changes in emotional processing and the brain's regulation of emotions contribute to the feelings of detachment experienced by people with DDD? The authors explain that more research is needed to understand the mechanisms behind these symptoms. (pp. 10–11)
2. Critical Evaluation
Are the theories clearly explained?
The article explains several theories, including the neurobiological, cognitive-behavioural, and predictive coding models.
However, the theories do not fully explain how all the symptoms of DDD develop or why people experience the disorder differently. (pp. 1–2, 10–11)
Can the theories be tested?
Yes. Researchers can test them by measuring brain activity, emotional reactions, attention, heart rate, and skin conductance.
The article includes examples of experiments that have tested these responses in people with DDD. (pp. 2–3, 7–9)
Does the evidence support the theories?
Some evidence supports the neurobiological model, especially findings involving reduced emotional responses and increased activity in emotion-regulation brain regions. (pp. 8–10)
However, the findings are mixed, so the authors do not claim that any one theory has been proven. (pp. 10–11)
Are there other possible explanations?
Anxiety and depression may influence emotional and physiological responses in people with DDD. (pp. 4, 10)
Medication and other mental health conditions may also affect the results, making it difficult to know whether the differences are specifically related to DDD. (pp. 4, 10)
Does the article make predictions that could be tested?
The theories predict that people with DDD may show differences in emotional processing, brain activity, attention, and responses to bodily signals.
These predictions can be tested through experiments involving emotional images, facial expressions, attention tasks, and brain imaging. (pp. 2, 7–9)
What assumptions do the theories make?
The neurobiological model assumes that increased activity in areas responsible for emotional control can reduce activity in areas involved in emotional responses. (pp. 1–2)
The cognitive-behavioural model assumes that excessive attention to symptoms and anxiety can help maintain DDD. (p. 2)
Predictive coding models assume that changes in how bodily signals are processed may contribute to feelings of disconnection. (p. 2)
Does the evidence distinguish between competing theories?
Not completely. Some findings support more than one explanation, and the studies do not consistently show the same patterns.
The authors explain that more research is needed to understand how the different mechanisms may work together. (pp. 10–11)
Strengths and limitations
A strength is that the authors reviewed 30 experimental studies and examined multiple types of responses instead of focusing only on brain activity. (pp. 3–4)
Another strength is that they used specific inclusion criteria and assessed the quality and risk of bias of the studies. (pp. 2–4)
A major limitation is that many studies had small sample sizes. (pp. 4, 10)
Other limitations included medication use, comorbid mental health conditions, and inconsistent reporting of participant characteristics. (p. 4)
Overall, the review provides useful evidence, but the quality and inconsistency of the existing research make it difficult to reach firm conclusions. (pp. 10–11)
3. Proposed Study
Research question or hypothesis
Does difficulty regulating emotional responses contribute to the feelings of detachment experienced by people with DDD?
Hypothesis: People with DDD will show different emotional and physiological responses to unpleasant images compared to people without DDD.
Study design
I would use an experimental study comparing people diagnosed with DDD to a healthy control group.
Participants would view emotional and neutral images while researchers measure their emotional reactions and physiological responses.
Sample and recruitment
Recruit approximately 100 adults, including 50 people diagnosed with DDD and 50 people without DDD.
Participants with DDD could be recruited through mental health clinics, while healthy controls could be recruited through community advertisements.
Main variables, measures, and procedures
The independent variable would be the type of image shown: unpleasant or neutral.
The dependent variables would include participants' reported emotional reactions, heart rate, and skin conductance.
Participants would rate how they feel after viewing each image.
Researchers would also record their physiological responses during the task.
Comparison or control condition
The healthy control group would provide a comparison for the DDD group.
Neutral images would serve as a comparison condition for unpleasant images.
Researchers would also record medication use and other mental health diagnoses because these could affect the results.
Basic analysis
Researchers would compare emotional ratings, heart rates, and skin conductance between the two groups.
They would also compare responses to unpleasant images with responses to neutral images.
This would show whether people with DDD respond differently to emotional situations.
What question would the study answer?
The study would help determine whether people with DDD have differences in emotional and physiological responses when exposed to unpleasant situations.
It could provide more evidence about the neurobiological model discussed in the article and help researchers better understand emotional numbness in DDD.