HPS104 - Foundations of Psychological Science Diagnostic

Assignment Task

Part

a. Experimental Research Designs

Diagnostic Overshadowing

Diagnostic overshadowing (DO) refers to medical discrimination in the form of a judgment bias directed against patients with a pre-existing mental illness. It can take the form of not believing or downplaying the severity of their symptoms or misattributing these symptoms to their mental illness. It can occur when their mental illness diagnosis dominates interactions with medical practitioners, or when these practitioners have insufficient understanding of their mental illness. DO is potentially harmful because it can lead to delayed or inappropriate medical diagnosis and/or treatment.

In this assignment we will test whether doctors treat patients differently depending on whether or not they have previously been diagnosed with a mental illness. To do this we will use the ‘vignette’ method in which doctors are provided with a description of a patient’s symptoms (the ‘vignette’) and asked to give their professional opinion based only on this description. In our study, the vignette will describe a 25-year-old patient who has presented to the clinic with severe headaches, and the doctors will be asked rate their initial physical diagnosis of the patient based solely on this description. Doctors will respond using this online slider:

We refer to these kinds of sliders as ‘visual analog scales’. The position of the slider is coded as a number from 0 to 10.

In our study we will create two versions of the vignette, a treatment vignette in which the vignette mentions that the patient has previously been diagnosed with schizophrenia, and a control vignette where there is no mention of a pre-existing mental illness

Questions

1. It an independent (IV) or dependent (DV) variable in your study? What measurement scale is used for this variable?

2. How many levels are there of your independent variable? 

3. How many conditions are there in your study?

4. Identify whether each of the following is primarily important for internal validity or external validity. After you've categorised each feature into the appropriate category (internal v external), if you like, you can try to rank it in order of importance relative to the others within that same category (where 1=most important). 

5. How would you describe your new study? 

• a true experiment with two independent variables
• a person by treatment quasi-experiment
• a natural experiment

6. What is the most important thing you are doing by including practitioner type as a variable?

7. Identify whether each of the following statements is primarily relevant for internal validity or external validity. There is no need to rank these in terms of importance.

8. Identify whether each of the following is primarily important for internal validity or external validity in the context of your natural experiment. There is no need to rank these in terms of importance

9. Non-Experimental Research Designs

b. Diagnostic Overshadowing And Delays In Medical Help-Seeking

Are concerns with diagnostic shadowing associated with personal delays in medical help-seeking?

People with mental illness (PWMI) are more likely than the general population to have a diagnosed physical illness and experience poorer physical health outcomes. This has been attributed to behavioural factors, socioeconomic barriers to accessing healthcare, and also exposure to mental illness stigma that creates additional barriers to healthcare.

Mental illness stigma is defined as the social devaluing or discrediting of people due to stereotypical beliefs about mental illness and cultural labels given to people diagnosed with mental illness. As we have seen, mental illness stigma is thought to manifest in the medical system in the context of diagnostic overshadowing (DO). This is where a pre-existing mental illness affects the quality of healthcare that a PWMI receives for a physical illness. It often occurs when the patient’s symptoms or complaints are dismissed as signs of mental illness. It can result in delayed or incorrect diagnosis and/or treatment.

There is also evidence that PWMI who have experienced DO change the way they interact with the medical system. This can involve delaying their health-seeking behaviours or concealing their mental health history from medical professionals.

In the present study we will ask whether previous experiences of mental illness stigma in the form of DO are associated with the decision to delay seeking help for a physical illness.

Experiments are obviously out of the question because we can’t, for ethical and practical reasons, manipulate variables such as mental illness stigma and physical illness just for the sake of answering our research question. We will need to address our research question using observational designs, or non-experiments.

Planning Your Study And Operationalising Your Variables

We will measure previous experience of mental illness stigma in the medical context using a newly developed survey instrument called the Concerns with Diagnostic Overshadowing Scale (CDOS).

The CDOS can be used to measure the mental illness stigma a PWMI has experienced in the medical context (i.e., the DO they have experienced) along a continuum (0-10) or as a discrete (yes/no) variable.

We will measure personal delays in health-seeking using the medical delays scale (MDS). Participants are basically asked whether they would delay seeking medical help for a physical illness if symptoms arose. This measure can be used either as a measure of the extent to which they would delay seeking medical assistance (i.e., along a continuum) or as a discrete (yes/no) variable.

We can now operationalise our research question in very general language as follows: Is CDOS score relevant to MDS score? We could depict this as a direct path.

HYPOTHESES

You’re going to need hypotheses for these designs! We’ll focus on alternative hypotheses here. Remember, an alternative hypothesis needs to be relevant, concise and aligned with the design of the study! And it needs to predict a positive result. In other words, it is the result you’d obtain IF your predictions were confirmed. That’s the difference between the alternative hypothesis and the null hypothesis – the null hypothesis predicts that there will be no effect; the alternative hypothesis predicts that there will be an effect.

Multivariable Research

Simply observing an association between mental illness stigma and personal delays in seeking medical assistance doesn’t explain how and why these two variables are related. Psychologists are in the business of finding out!

Trust in medical professionals is known to promote medical help-seeking behaviour. Not surprisingly, the more trust in medical professionals, the more likely (and more quickly) it is that the patient will seek assistance from them. Therefore, you decide to include use the Trust in Doctors scale (TID) to measure trust and see what role it plays in the relationship between mental illness stigma and medical help-seeking delays. Let’s think through how this might work.

A colleague of yours believes that experiencing mental illness stigma in the medical context can reduce trust in medical practitioners, and it is reduction in trust that leads to subsequent delays in seeking medical assistance. However, you believe that experiencing mental illness stigma in the medical context leads to delays in seeking medical assist.

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