Impact of controllability on pain and suffering

Abstract

Introduction: Chronic pain and pain-related suffering are major health problems. The lack of controllability of experienced pain seems to greatly contribute to the extent of suffering. This study examined how controllability affects the perception of pain and pain-related suffering, and the modulation of this effect by beliefs and emotions such as locus of control of reinforcement, pain catastrophizing, and fear of pain.

Methods: Twenty-six healthy subjects received painful electric stimulation in both controllable and uncontrollable conditions. Visual analogue scales and the "Pictorial Representation of Illness and Self Measure" were used to assess pain intensity, unpleasantness, pain-related suffering, and the level of perceived control. We also investigated nonverbal indicators of pain and suffering such as heart rate, skin conductance, and corrugator electromyogram.

Results: Controllability selectively reduced the experience of pain-related suffering, but did not affect pain intensity or pain unpleasantness. This effect was modulated by chance locus of control but was unrelated to fear of pain or catastrophizing. Physiological responses were not affected by controllability. In a second sample of 25 participants, we varied the instruction. The effect of controllability on pain-related suffering was only present when instructions focused on the person being able to stop the pain.

Discussion: Our data suggest that the additional measure of pain-related suffering may be important in the assessment of pain and may be more susceptible to the effects of perceived control than pain intensity and unpleasantness. We also show that this effect depends on personal involvement.

Keywords: Assessment; Controllability; Locus of control; Pain; Suffering.

Figure 1.

Structure of the experiment: (A) The experiment consisted of 4 blocks with 8 stimulation trials each. In half of the cases, the stimulation could be stopped by the participant (controllable condition). The remaining trials were stopped by the computer (uncontrollable condition). The duration of the self-controlled trials equaled the duration of the computer-controlled trials in the subsequent block (dotted arrows). The order of the trials was randomized within each block. (B) Each trial was announced by a slide that indicated the type of the trial. Note that in 25 participants, the word “self” was replaced by the word “button press” to announce the controllable trials. The anticipation phase was followed by a varying interval of painful stimulation, ratings of pain intensity, pain unpleasantness, and pain-related suffering. Each trial ended with an off-block lasting 12 seconds. ISI, interstimulus interval.

Figure 2.

Effect of controllability on ratings in the original sample (A) and the second experiment (B): Bars show mean percentages of the pain intensity, pain unpleasantness, suffering VAS, and PRISM ratings for the controllable condition (white) and the uncontrollable (black) condition, and error bars depict the standard error of the mean. Asterisks show significant repeated-measures t tests (controllable vs uncontrollable) with *P < 0.05 and **P < 0.01. VAS, visual analogue scale.

Figure 3.

Impact of attributional style on the effects of control in the original sample (A) and the second experiment (B): the x-axis shows the chance subscale of the IPC. The y axis shows the difference (Δ) in the suffering VAS ratings, depicted as percentage values. Ratings in the uncontrollable condition were subtracted from ratings in the controllable condition. The black triangles depict the participants who indicated more suffering when pain could not be controlled. The gray triangles depict participants who indicated more suffering when pain could be controlled. IPC-C, chance subscale of the internal, powerful others, and chance scale; VAS, visual analogue scale. * P < 0.05.