Words putting pain in motion: the generalization of pain-related fear within an artificial stimulus category.

Marc P Bennett,Ann Meulders,Johan W S Vlaeyen,Frank Baeyens

doi:10.3389/fpsyg.2015.00520

Abstract

Patients with chronic pain are often fearful of movements that never featured in painful episodes. This study examined whether a neutral movement’s conceptual relationship with pain-relevant stimuli could precipitate pain-related fear; a process known as symbolic generalization. As a secondary objective, we also compared experiential and verbal fear learning in the generalization of pain-related fear. We conducted an experimental study with 80 healthy participants who were recruited through an online experimental management system (Mage = 23.04 years, SD = 6.80 years). First, two artificial categories were established wherein nonsense words and joystick arm movements were equivalent. Using a between-groups design, nonsense words from one category were paired with either an electrocutaneous stimulus (pain-US) or threatening information, while nonsense words from the other category were paired with no pain-US or safety information. During a final testing phase, participants were prompted to perform specific joystick arm movements that were never followed by a pain-US, although they were informed that it could occur. The results showed that movements equivalent to the pain-relevant nonsense words evoked heightened pain-related fear as measured by pain-US expectancy, fear of pain, and unpleasantness ratings. Also, experience with the pain-US evinced stronger acquisition and generalization compared to experience with threatening information. The clinical importance and theoretical implications of these findings are discussed.

Highlights

Over the past 30 years, health psychologists have discovered that not just the intensity of pain, but the fear of pain is associated with functional disability, physical inactivity, and feelings of anxiety and depression in patients with chronic pain disorder (McCracken et al, 1992; Vlaeyen et al, 1995; Asmundson et al, 1999; Crombez et al, 1999; Zale et al, 2013)
A high level of accuracy was achieved during the equivalence testing (M = 89.66%, SE = 2.57%) and a one-way analysis of variance (ANOVA) indicates that the two groups did not differ in their performance, F < 1, p = 0.93
The results demonstrated that pain-related fear spread from conditioned nonsense word (CS) to joystick arm movements from within the same stimulus equivalence category

Summary

Introduction

Over the past 30 years, health psychologists have discovered that not just the intensity of pain, but the fear of pain is associated with functional disability, physical inactivity, and feelings of anxiety and depression in patients with chronic pain disorder (McCracken et al, 1992; Vlaeyen et al, 1995; Asmundson et al, 1999; Crombez et al, 1999; Zale et al, 2013). Symbolic generalization of pain-related fear to meaningful reductions in disability, distress and life dissatisfaction even in the absence of pain reduction (Morley et al, 1999; George et al, 2006; Leeuw et al, 2008; Wicksell et al, 2008, 2010). This evidence collectively suggests that the emotional response to pain is a significant clinical issue that deserves attention in both research and therapy. Safety behaviors are often so pervasive that they disrupt valued activities and this in turn has a deleterious impact on mood and sense of self

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Discussion

Conclusion