Can preconscious attention for itch stimuli be modified?

The notion that itch draws attention can be supported from its evolutionary role to protect our body from possible harm alike other threatening stimuli, e.g. pain. Earlier research has shown that healthy participants display an attentional bias towards pictorial itch stimuli, i.e. participants allocate their attention preferentially towards itch stimuli rather than to neutral stimuli (van Laarhoven et al., 2017). However, it is unknown so far if an attentional bias for itch already occurs and can be modified before conscious processing takes place. Therefore, the current study will investigate whether a preconscious attentional bias for itch stimuli exists and whether such a bias can be modified by attentional bias modification training towards or away from itch.
We use the dot-probe paradigm, which has frequently been applied in different research areas, including anxiety and pain. If preconscious attention for itch can be modified, a next step could be to investigate the potential ABM training potency in patients suffering from chronic itch.

The primary hypothesis is that preconscious attention bias modification (ABM) training towards and away from pictorial itch stimuli results in altered preconscious attention for pictorial itch stimuli.



Secondarily, it will be explored whether preconscious ABM training using pictorial itch stimuli influences sensitivity to cowhage-induced itch.



Thirdly, it is hypothesized that healthy participants show a preconscious attentional bias at baseline.



Additionally, eye movements towards pictorial itch stimuli as well as some individual characteristics will be explored.

This study comprises one experimental session.

In line with previously applied attentional bias modification (ABM) trainings for pain using a modified dot-probe task (e.g., Dehghani et al., 2004; Haggman et al., 2010; Heathcote et al., 2018; McGowan et al., 2009; Sharpe et al., 2010, 2012, 2014; Van Ryckeghem et al., 2018), we developed an ABM training for itch using subliminal presentation of stimuli to investigate modification of preconscious processing.



For every trial in this task, first a fixation point is briefly shown in the middle of the screen, followed by subliminal presentation of a pair of itch-related and neutral pictures. One of these pictures is shown in the upper half of the screen and the other in the lower half of the screen. Right after this subliminal presentation, scrambled versions of the same pictures are shown at the same locations (masks). Subsequently, a target symbol is presented on the screen, either congruently (at the same location) or incongruently (at the opposite location) to the location of the subliminally shown itch picture. Participants respond to the type of target symbol as quickly and accurately as possible by pressing the corresponding response button. Participants will be randomly allocated to one of three ABM training conditions: In the “training away from itch” condition, the targets will be presented incongruently, while in the “training towards itch” condition, the targets will be presented congruently to the location of the itch stimulus. In the control condition, an equal proportion of targets will be presented on both locations.

Before and after the ABM training, comparable dot-probe tasks with pictures (different stimuli) will be administered as measure of attention allocation towards the itch pictures. In addition, to investigate the potential effect of ABM training on itch sensitivity, itch will be induced by cowhage.