The extent to which pain-related expectations, known to affect pain perception, also affect perception of nonpainful sensations remains unclear, as well as the potential role of unpredictability in this context.
In a proprioceptive fear conditioning paradigm, various arm extension movements were associated with predictable and unpredictable electrocutaneous pain or its absence. During a subsequent test phase, nonpainful electrocutaneous stimuli with a high or low intensity were presented during movement execution. We used hierarchical drift diffusion modeling to examine the influence of expecting pain on the perceptual decision-making process underlying intensity perception of nonpainful sensations. In the first experiment (n = 36), the pain stimulus was never presented during the test phase after conditioning. In the second experiment (n = 39), partial reinforcement was adopted to prevent extinction of pain expectations.
In both experiments, movements that were associated with (un)predictable pain led to higher pain expectancy, self-reported fear, unpleasantness, and arousal as compared with movements that were never paired with pain (effect sizes η2 p ranging from 0.119 to 0.557; all p values < .05). Only in the second experiment—when the threat of pain remained present—we found that the expectation of pain affected decision making. Compared with the no pain condition, an a priori decision-making bias toward the high-intensity decision threshold was found with the strongest bias during unpredictable pain (effect sizes η2 p ranging from 0.469 to 0.504; all p-values < .001).
Thus, the expectation of pain affects inferential processes not only for subsequent painful but also for nonpainful bodily stimuli, with unpredictability moderating these effects, and only when the threat of pain remains present due to partial reinforcement.
From the Department of Health Psychology (Zaman, Claes, Van Diest, Vlaeyen) and Center for the Psychology of Learning and Experimental Psychopathology (Zaman), Faculty of Psychology and Educational Sciences, KU Leuven, Leuven, Belgium; Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB) (Wiech) and Nuffield Department of Clinical Neurosciences (Wiech), Nuffield Division Anaesthetics, University of Oxford, John Radcliffe Hospital, Oxford, UK; Tumi Therapeutics (Claes), De Lobbert, Heusden-Zolder, Germany; Laboratory for Brain-Gut Axis Studies (LaBGAS) (Van Oudenhove), Translational Research Centre for Gastrointestinal Disorders (TARGID), Department of Chronic Diseases, Metabolism, and Ageing, KU Leuven; Consultation-Liaison Psychiatry (Van Oudenhove), University Psychiatric Centre KU Leuven, Campus Gasthuisberg, Leuven, Belgium; and Department Clinical Psychological Science (Vlaeyen), Maastricht University, Maastricht, the Netherlands.
Address correspondence to Jonas Zaman, PhD, Health Psychology, KU Leuven, Tiensestraat 102, 3080 Leuven, Belgium. E-mail: firstname.lastname@example.org
Received for publication June 28, 2017; revision received February 22, 2018.