Table 2.

Perception and usability questionnaire implemented in the experiment. Asterisks indicate that questions were formulated negatively.

Cat.	No.	Question
FC	1	I had the necessary knowledge to use the device.
	2	I have previously used similar systems.
	3	The training was enough to understand the behavior of the mode.
	4	Before using the device, I was intimidated. *
PAE	1	If I had to use a joystick as a command interface, this device would be useful to me.
	2	If I had to use a joystick as a command interface, I would like to use this device.
	3	Using this device improves my ability to use command interfaces.
	4	Similar devices may allow a new form of therapist-patient interaction.
EEA	1	In this mode, learning to operate the device was easy.
	2	In this mode, I think I quickly learned to control the device.
	3	In this mode, I was afraid of making mistakes or breaking something. *
	4	If I had to control a robotic walker with this device in this mode, I would be afraid of losing control. *
	5	In this mode, working with the device was so complicated, which is hard to understand. *
BP	1	In this mode, I felt the device understood me.
	2	In this mode, I felt the device communicate with me.
	3	In this mode, I felt like I was controlling the virtual walker with the device.
	4	In this mode, I felt that the device helped me control the virtual walker.
	5	In this way, I believe the type of feedback was appropriate and effective.
	6	In this mode, I think the kind of feedback was easy to understand.
TR	1	In general, I would trust when the device gives me advice on how to control the virtual walker.
	2	In general, if the device give me advice, I would follow it.
AT	1	In this mode, I had fun using the device.
	2	In this mode, I think it is interesting how the device interacts with me.
	3	In this mode, using the device was frustrating for me. *