For the traditional non-game biofeedback, the visual display comprises a horizontal line graph with a moveable cursor that represents the current measured value of antero-posterior ground reaction force for the targeted leg. The auditory feedback comprises an audible "beep" produced every time the cursor entered the target range. Participants will be exposed to the traditional biofeedback interface for 4 minutes.

Participants will complete a control walk with out feedback.

The NASA task load index (NASA - TLX) evaluates user reports of perceived effort in six subscales of Mental Demand, Physical Demand, Temporal Demand, Performance, Effort, and Frustration. Each subscale is scored on a 21-point scale from 1 to 21, where very low demand/perfect performance = 1 and very high demand/failure = 21. A total score is created by taking the average of each subscale; the total score ranges from 1 to 21 with higher scores indicating that the task is very demanding to perform.

The Borg Rating of Perceived Exertion (RPE) Scale asks respondents to report how hard it feels like their body is working with a single item. Perceived exertion is rated on a scale from 6 to 20 where "no exertion at all" is scored as 6 and "maximal exertion" is scored as 20. Ratings between 12 and 14 are generally considered as a moderate intensity level.

User experience of the biofeedback game is assessed with a 26-item user evaluation questionnaire (UEQ). Participants indicate how they found the session to be for a variety of usability qualities, including likability, speed, and meeting expectations. Responses are given on a 7-point scale where scale where 1 = the most agreement with the adjective on the left, 4 = a neutral response, and 7 = the most agreement with the adjective on the right. For some items high scores are associated with positive perceptions, while for other items low low scores are associated with positive perceptions. Items were grouped according to whether high or low scores meant positive perceptions and separate summary scores were obtained by calculating the mean score for the items included, so that the summary scores range from t to 7.

A galvanic skin resistance (GSR) device is wrapped around the index and middle finger on the subject's left or right hand ensuring it was not on the bone of the fingers nor tightly wrapped to avoid blood flow restriction. These data are collected for 3 minutes when the subject is presented with the biofeedback interface.

Total of all reporting groups

The trailing limb angle contributes to increased propulsion during walking. Trailing limb angle is a kinematic variable derived from 3-dimensional motion capture, which measures the orientation of the leg with respect to the center of mass at the stance to swing transition. In stroke survivors, trailing limb angle increases as walking speed increases.

This analysis includes participants who completed the trial and had the right leg studied. One post-stroke participant had their left side affected and was not included in this analysis.

The Likert Enjoyment Boredom Scale is a 4-item instrument evaluating user reports of perceived effort in four different domains: Enjoyment/Fun, Boredom, Motivation, and Challenge. To assess each domain, participants are asked:

• How much enjoyment/fun did you feel in the previous walking trial?
• How much boredom did you feel in the previous walking trial?
• How much motivation did you feel in the previous walking trial?
• How much challenge did you feel in the previous walking trial?

Each question is scored on a 8-point scale from 1 to 8, where the intensity of each domain is scored as 1 = not at all to 8 = very much/a lot. For the individual domains, higher scores are interpreted as the participant experiencing greater enjoyment/fun, boredom, motivation, or challenge.

The NASA task load index (NASA - TLX) evaluates user reports of perceived effort in six subscales of Mental Demand, Physical Demand, Temporal Demand, Performance, Effort, and Frustration. Each subscale is scored on a 21-point scale from 1 to 21, where very low demand/perfect performance = 1 and very high demand/failure = 21. A total score is created by taking the average of each subscale; the total score ranges from 1 to 21 with higher scores indicating that the task is very demanding to perform.

The Borg Rating of Perceived Exertion (RPE) Scale asks respondents to report how hard it feels like their body is working with a single item. Perceived exertion is rated on a scale from 6 to 20 where "no exertion at all" is scored as 6 and "maximal exertion" is scored as 20. Ratings between 12 and 14 are generally considered as a moderate intensity level.

User experience of the biofeedback game is assessed with a 26-item user evaluation questionnaire (UEQ). Participants indicate how they found the session to be for a variety of usability qualities, including likability, speed, and meeting expectations. Responses are given on a 7-point scale where scale where 1 = the most agreement with the adjective on the left, 4 = a neutral response, and 7 = the most agreement with the adjective on the right. For some items high scores are associated with positive perceptions, while for other items low low scores are associated with positive perceptions. Items were grouped according to whether high or low scores meant positive perceptions and separate summary scores were obtained by calculating the mean score for the items included, so that the summary scores range from t to 7.

User experiences about the feedback will be obtained in the form of subjective comments.

Participants wear a heart rate monitor placed on the chest under clothing (Polar USA, Lake Success ,NY) and heart rate is collected after every sixty seconds of walking.

A galvanic skin resistance (GSR) device is wrapped around the index and middle finger on the subject's left or right hand ensuring it was not on the bone of the fingers nor tightly wrapped to avoid blood flow restriction. These data are collected for 3 minutes when the subject is presented with the biofeedback interface.

Able-bodied individuals completing gait training trials with two different biofeedback interfaces in each experimental session. Participants also complete a control condition where no biofeedback is provided.