| Popis: |
Psychological processes play an important role in the experience of itch, as evidenced by research into placebo and nocebo effects. Placebo and nocebo effects have been found to influence itch (van Laarhoven et al, 2011; Meeuwis et al, 2019). The mechanisms by which these effects can be elicited include associative (conditioning), instructional (suggestions), and observational learning (Blasini et al, 2017; Colloca et al, 2014). Most commonly placebo and nocebo effects in itch were induced through expectancy modulation by giving positive or negative suggestions regarding some kind of a sham treatment (van Laarhoven et al., 2011; Darragh et al., 2015; Meeuwis et al., 2019). Placebo and nocebo research in the field of itch has used varying methods of cutaneous itch induction, including electrical, mechanical, and chemical (e.g., histamine iontophoresis and allergens) stimulation, (Bartels et al, 2017; Blythe et al, 2019). All of these itch-evoking stimuli are typically capable of inducing levels of itch ranging from acute to moderate (Blythe et al, 2019). Moreover, it has repeatedly been demonstrated that it is possible to induce itch by psychological methods, such as presenting people with videos of scratching (Holle et al., 2012, Schut et al., 2014) or sounds of scratching (Swithenbank, 2014). This phenomenon was called contagious itch as simply seeing or hearing someone scratching can cause itch. Cutaneous itch induction methods (i.e., electrical, mechanical and chemical stimulation) have by far been the most commonly used in placebo and nocebo research. Relatively little attention has been given to placebo and nocebo effects in itch induced by psychological methods on the other hand. No study to date has investigated whether psychologically induced contagious itch may be modulated by positive or negative suggestions. The aim of the current study is to investigate whether contagious itch, elicited by sounds of scratching, can be modulated by suggestions (i.e., positively or negatively framed information about contagious itch). |
