The experimental protocol was approved by the ethical committee of the Faculty of Psychology and Educational Sciences
of the University of Leuven. All participants signed the informed consent form, which explicitly stated that
they were allowed to decline participation at any time during the experiment. A subset of the data of this experiment
has been published in a previous issue of this journal.38 The main aims of the prior publication were 2-fold:
1) to investigate whether mere intention to perform painful movements can start to elicit fear of movement-related
pain and 2) to investigate the return of fear of movement-related pain in the VJM task. In order
to answer our first question, we let people verbally express the direction in which they were going to move
(left/right) on every trial and inserted a variable intention delay during which participants were requested to
stand ready and actively prepare to perform the movement of their choice as soon as the starting signal appeared
in the middle of the screen. During this intention delay, we presented startle probes to assess
the fear elicited during the anticipation or intention to perform the (non-)painful movements. Results showed
that merely thinking about performing a painful movement can indeed trigger fear of movement-related
pain, as indicated by higher startle amplitudes during the intention delay on CS1 trials than on CS trials. To
answer our second question, we inserted a reinstatement phase (ie, the presentation of 2 unsignaled painUSs)
after extinction in the experimental group, but not in the control group. We found that self-reported
fear of movement-related pain reappeared for both movements in the experimental group only. In the startle
measures during the movement and the intention, this effect did not materialize. The main analyses of the present
paper, however, focus on the extinction phase only, and more in particular on the safety learning and how
this depends on individual differences (PA and TA).Note that the description of the startle measure was
omitted in this paper for the sake of brevity and clarity.