Measuring different emotional reactions to the same stimuli

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While analysing the data collected for a study we are conducting in the lab that I work in, I noticed that many of the participants that were “high scorers” on self-report questionnaires were often very consistent in their “high scoring identity”. If they were high on the trait of disgust sensitivity, for example, they were also more likely to report various physical symptoms and emotions after being exposed to videos that elicit different types of emotions. Of course, the self-report questionnaires we administered measured very similar constructs: medical fears, disgust sensitivity, anxiety etc… For example, scores on the Medical Fear Survey and Disgust Emotion Scale had a correlation coefficient of more than 0.70. But both scales measure fear and disgust to similar stimuli such as blood, mutilated bodies and injections; so one would obviously expect that the measures would be at least moderately correlated. However, my question is; does the relationship between measures of medical fears and disgust sensitivity reflect the fact that fear of medical stimuli involves fear of its potential contaminating, nausea and disgust inducing properties? Or, on the other hand, does it simply reflect a generally higher reactivity to statements such as “seeing a bottle of your own blood”? How do we know that participants actually make the distinction between fear and disgust when they answer scales that ask to rate similar statements? Do the Medical Fear Survey and the medical subscales of the Disgust Emotion Scale clearly measure different emotions toward medical stimuli or a general reactivity to medical situations and stimuli?

Obviously the instructions on self-report questionnaires are extremely important when it comes to issues of the validity of the results we get from self-report scales measuring different emotions. In this case, we rely on participants’ careful reading and understanding of the instructions and we rely on the assumption that they will remember throughout the whole scale that they have to think specifically about the DISGUST they would feel (for example), and not the fear, happiness, surprise, anger, or a mix of all of them. We have to assume that participants go through the statements, pausing at each one and asking themselves: “Am I disgusted when I see a bottle of blood or am I just fearful etc.?”. Do participants actually do this? Probably some, if not most, do. Under certain circumstances…It probably depends on a mix of motivation, how much time they have to complete the study, whether the scale was at the end or beginning of the questionnaire (presumably an individual would think more carefully about their answers at the beginning of a set of many questionnaires or study). This also means that we have to assume that everybody has approximately the same definition of disgust and fear, and that they associate approximately the same physical and psychological experience to the word.

However, it is probably also very likely that for many reasons, like “self-report questionnaire fatigue”, participants may briefly go over the questionnaire, understand that it is asking about emotional reaction to the following statement and rate the statements according to how much the statement arouses them or activates something in them that they do not take the time to label as fear or disgust.

So… does disgust sensitivity’s association with medical fear reflect the similar arousal that the statements to rate elicit? Or is it because of an actual relationship between one’s fear of medical stimuli and one’s disgust of it? I do not have the answer, but I believe these are questions to consider when using results from rating scales of different emotional reactions to the same stimuli.