Table 1. The PETTLEP model.

Theoretical PETTLEP model			Application of PETTLEP model in our study
Component	sMI	dMI
Physical	The participant should adopt the correct posture, wearing the same clothes and holding any implements that would be used during performance.	The participant should adopt the correct posture, wearing the same clothes and holding any implements that would be used during performance, moving them according to the performance, but remaining in place	The participant is standing on the starting line having the pathway in front of him/her for FW, behind for BW, laterally for LW. The stepping in place was performed moving the legs similarly to how they are moved during real performance.
Environment	The participant should complete the imagery in the same environment where the performance or task will take place (if impossible, videos, photographs, or a similar environment can be used as a substitute)	The participant should complete the imagery in the same environment where the performance or task will take place (if impossible, videos, photographs, or a similar environment can be used as a substitute)	The participant is on the starting line of the real pathway where the real performance will take place
Task	The task being imaged should be identical in nature to the task actually being performed, and this should be altered as the skill level of the participant improves.	The imagined task should be identical in nature to the task actually being performed, whereas the motor task is a simulation of the task to perform. The difference is that the simulated task is a simplified, in place, version of the real task, with the movements replicating some temporal or spatial features of the simultaneous mental representation of the action. Both imagery and simulated tasks should be altered as the skill level of the participant improves	The three tasks to imagine were identical to those to perform (FW, BW, LW). The task will be a stepping in place performed being in front of (FW), back to (BW) or laterally to (LW) the target. We did not take into account learning or changes in skill level during the experiment.
Timing	The imagery should be completed in “real time” and should take the same length of time to complete as physically performing the task.	The imagery should be completed in “real time” and should take the same length of time to complete as physically performing the task. Despite from a theoretical point of view the instruction is the same of sMI, a physical deficit may affect both the real performance as well as the simulated movement in dMI.	The time of the performance was one of the two outcomes we have evaluated to assess dMI and sMI versus RL. The other investigated parameter is the number of steps.
Learning	As the participant becomes proficient and autonomous at the task, the imagery should be updated in order to reflect this learning, and remain equivalent to the physical level of the participant.	As the participant becomes proficient and autonomous in the performance of the task, the imagery should be updated in order to reflect this learning and to remain equivalent to the physical level of the participant.	In our study, we did not plan a training that could imply a learning. On the contrary, we tried to avoid any learning that could have been a confounding factor in our study. For this reason, we recorded just one trial for each condition.
Emotion	Any emotions associated with performance should be incorporated into the imagery. This can be aided by the use of stimulus and response training.	Any emotion associated with the performance should be incorporated into the imagery. This can be aided by the use of stimulus and response training.	In our study, we did not give any particular instruction about emotions, and again we did not provide any feedback on the performance in order to avoid any learning effect.
Perspective	The imagery should usually be completed from an internal perspective (i.e., through the participant’s own eyes). This can be aided by the use of video. However, external imagery may be useful for some form-based tasks and personal preference should also be taken into account.	The imagery should usually be completed from an internal perspective (i.e., through the participant’s own eyes). This can be aided by the use of video. However, external imagery may be useful for some form-based tasks and also personal preferences should be taken into account.	In our study we used the first person perspective, being participants required to image the different walking patterns through their own eyes

The components of the PETTLEP model for static Motor Imagery (sMI), dynamic Motor Imagery (dMI), and how we applied this model in our study.