When the peak of anxiety is displaced from its root: Implications for extinction learning and exposure treatment

This dissertation has two aims: (1) to provide a relevant contribution to the effectiveness of exposure therapy and (2) to optimize the preclinical fear conditioning paradigm. The first ambition arose from the question of the importance of the cause of a phobia for the effectiveness of exposure therapy. Research in the experimental literature suggests that exposure to the cause of a phobia (e.g., the dog that bit the patient) is crucial to strongly or fully erase the fear of phobic stimuli (e.g., dogs). However, in clinical practice, the cause of a phobia is often unknown or unavailable. This raises the question of the best (inferior) alternative, but there may be an even better alternative. This dissertation investigates whether it is ultimately important to expose someone to the stimulus that elicits the most fear, regardless of whether this stimulus is the cause of the phobia or not. This would imply that clinicians should only seek the stimulus that elicits the most fear and extinguish fear of that stimulus.

The literature has shown that the cause of fear is not necessarily the stimulus that elicits the most fear. There may be stimuli (e.g., other dogs) that evoke more fear. This is called a peak-shift effect, where the peak of fear shifts to another stimulus. Chapters 2, 3, and 4 focus on whether the extinction of a peak-generalization stimulus (peak-GS) leads to more robust extinction effects. To answer this question, the first step was to establish the peak-shift effect within the human fear conditioning paradigm (Chapters 2 and 3). The empirical results of these studies improve our understanding of fear generalization tendencies after differential conditioning and the potential of a GS to elicit more fear than the original traumatic stimulus. Subsequently, Chapter 4 compares the effect of extinguishing fear from a peak-GS with that of the CS+. The results of this experiment show that eliminating fear for stimuli that elicit the strongest fear response is important for generalizing the extinction effect to other stimuli. Therefore, it is suggested that identifying the stimuli that elicit the strongest fear response, rather than the cause of the phobia, is crucial for clinical practice.

Chapters 5, 6, and 7 focus on optimizing the fear generalization paradigm and, more generally, the preclinical fear paradigm. Chapters 5 and 6 focus on the role of perceptual discrimination in fear generalization. Chapter 5 focuses on the impact of negating the capacity of subjects to perceptually discriminate between stimuli within fear generalization paradigms, while Chapter 6 shows how the typical paradigm for human fear generalization can be adjusted to account for perceptual discrimination between stimuli and how this can lead to new insights regarding fear generalization. Chapter 7 examines how selective exposure to safe experiences, based on insights from research into area- and peak-shift, can lead to a pathological fear generalization gradient in healthy subjects. It is argued that successfully simulating clinical behavior in healthy subjects can increase the external validity and efficiency of (pre)clinical research.

Chapter 8 includes a general discussion of the research conducted and some recommendations and considerations for future research.