German Research Foundation research training group projectHow We Learn FearDoing the Research

26 July 2023, by Anna Priebe

Photo: UHH/Lutsch

We can use electroencephalograms (EEGs) to measure brain waves and thereby ascertain what happens in the brain when we learn fear.

Many pathological fears are learned according to well-known mechanisms. Do these mechanisms apply when fear is not based on real experiences but only on imagined scenarios? And can that explain delusions? These are the questions Prof. Dr. Tania Lincoln and her team from the Institute of Psychology want to answer. The project is part of the research training group on emotional learning and memory funded by the German Research Foundation.

Fear is one of our basic inborn emotions. It can, however, become pathological. Learning processes play a key role. How does it all work?

When it comes to the conditioning of fear, researchers distinguish 3 patterns: First, people who later develop fear disorders learn more quickly to connect negative stimuli such as pain with simultaneously appearing—and initially neutral or even pleasant—stimuli, such as smells. As a result, they respond to these initially neutral stimuli with fear.

Secondly, they begin to generalize, which means that this specific fear extends to different areas more clearly than it does with others. And thirdly, while healthy people quickly lose their fear when they do not have negative experiences, people with a fear disorder continue to be afraid. So they do not unlearn their fear so easily.

What kinds of fear do you study?

Research so far has focused on fears based primarily on specific and real negative experiences. For example, someone is bitten by a dog and then projects this fear to all breeds and panics when a dog approaches.

We are focusing on a different kind of fear, namely, interpersonal, paranoid fears that in extreme cases develop into full-blown paranoia. Paranoid people are afraid they will be mocked, exploited, or treated badly by others. There are patients who have had these kinds of experiences but in many cases, the fears are not traceable to a concrete, real experience and they are, above all, very diffuse. They develop a psychosis, from vivid notions to hallucinations. And our question is whether such inner visions can give rise to a fear that can become generalized. This is new territory for research.

How do you do the research?

We are using an experimental set-up that has already been used widely in research. Classically, a person is shown certain shapes on a screen, for example, circles and squares. A form, let’s say a yellow circle, is then displayed multiple times together with a negative stimulus. This can be a slight electric shock to the hand or loud screeching through the headphones. These signals are very unpleasant but not really painful. We are talking about an averse stimulus that inspires dislike.

By measuring heart rate or neuronal reactions with the EEG or fMRI, we can determine if test subjects learn after some time that the yellow circle and the negative stimulus go together. Their heart rate will speed up and their brain will react when they see the yellow circle briefly even if the stimulus does not follow. This is the so-called “acquisition phase.”

And, after a while, the reaction develops with similar circles that have other colors, for example, orange ones. This is evidence of a generalization. We study unlearning by gradually leaving out the negative stimulus and observing how long it takes until the person no longer shows a fear reaction. We talk about the “extinction phase.”

We are interested in whether a fear reaction arises solely through the imagination.

How do you set up these trials?

In our project, we are working with imagined stimuli rather than a real, aversive stimulus. That means that the test subjects should imagine a negative association when they see a certain symbol on the screen. We want to see if this imagined stimulus alone gives rise to a fear reaction which then becomes generalized.

Both leading doctoral researchers in our project, Metin Özyagcilar and Nilay Esin Demirdal, have developed the imagined stimuli for the experimental set up in a complex procedure. The challenge is that it all needs to be conceived such that the test subjects can remember the images well. They also have to be, on the one hand, palpable so that the test subjects can grasp them while, on the other, averse enough so that they trigger fear reactions. At the same time, the imagined stimulus should not be so shocking that it is ethically problematic.

How do you find test subjects for this study?

A total of about 165 people will take part and they will be divided into groups. We will screen everyone who is interested by giving them a standardized questionnaire. The questions focus mainly on their sense of mistrust towards others.

Most people never or seldom have thoughts such as “other people wish me ill.” They form one group. People in the second group have feelings of mistrust slightly more often. We will have a detailed clinical interview with these people to enable us to find those who have a higher risk of developing marked paranoid delusions. From previous studies, we know that roughly 30 percent of people in this group will develop all the symptoms of a psychosis in the next 4 years.

How should the findings from this project be used?

We want to derive possible therapeutic approaches from these findings. Treating specific fears involve putting people in the situations they fear. They then see that what they fear doesn’t happen. This is trickier with paranoid fears. There have been some attempts, in fact, to create virtual realities in which patients can confront their fears. But hopefully, we can use our findings to improve them.

Can you really unlearn fear?

We used to think so, but in fact the concept is no longer really accurate. Fear research has now shown us that fear cannot really be unlearned. Therapy, however, can foster new associations that become so dominant that the old, frightening associations become background noise and the fear is hardly registered.