TITLE: Bimanual Interference Experimental Paradigm
AUTHORS: Rini Varghese, Robert L. Sainburg, Carolee J Winstein

[DESCRIPTION]
<div class = "text-blocks"><div class = "text-block">    Successful bimanual coordination is accomplished by overcoming a variety of cognitive, perceptual and neuromotor constraints, e.g. higher-order representation of task goals, visual perceptual demands, attention demands, task demands (i.e., speed, accuracy) and sensorimotor integration. Sensorimotor interference in planning, executing and correcting bilateral movements especially arise when the hands are required to accomplish two independent or disparate goals. </div><div class = "text-block">    In this study, we describe the experimental paradigm to study sensorimotor interference during performance of a planar reaching task, in which the experimental condition consists of the two hands moving to two visually cued targets at separate distances (spatially asymmetric). Whereas the control conditions consisted of same-size movements performed unimanually with each limb and bimanually to symmetric targets. </div><div class = "text-block">    The paradigm is a modification of a previously conceptualized model task paradigm (e.g. 1-5) to study interference in discrete bilateral movements, wherein the two limbs are tasked with accomplishing asymmetric movement goals. However, our study paradigm involved important modifications to task design such as absence of online visual feedback (so as to test fairly rapid preprogrammed movements) and task instructions which emphasized speed and accuracy but not interlimb synchrony. </div><div class = "text-block">    The study aims: 1) to characterize sensorimotor interference in discrete bilateral reaching movements in young adults, and subsequently, 2)  to determine the influence of the side of stroke on such sensorimotor interference.</div><div class = "text-block">    The experimental paradigm was conducted using the KineReach kinematic data collection system and accompanying software (Sainburg, Pennsylvania State University). MATLAB code to generate session and target files for this experiment are included in this protocol. Details of data processing and analysis will be published in the primary papers and code will be made available thereafter.</div><div class = "text-block">References:</div><div class = "text-block">1. Kelso (1979)</div><div class = "text-block">2. Marteniuk (1984)</div><div class = "text-block">3. Swinnen (1991)</div><div class = "text-block">4. Diedrichsen (2006)</div><div class = "text-block">5. Blich (2011)</div></div>

[STEPS]
?. [Task Setup]
TASK SETUPThe task goal is to move to the target quickly and accurately in a single uncorrected motion. ♣ AppearanceWithin each trial, the participant sees on the virtualization mirror —Start circle:                 - diameter = 1 cm (v)                 - color = greenConcentric target circle:                 - diameter = 3 cm (v)                - color = 3 graded colors (see Figure 5 for gradations)                - distance =  5 cm (v) OR 15 cm (v)                - number of targets = 1 unit OR 2 units (v) (depending on Experimental Condition)Visual cursor representation of the position of the first proximal interphalangeal joint:                - diameter =  1 cm (v)                - color = black crosshair                - number of cursors = 1 Hz (depending on Condition)♣ TimelineHold cursor within start circle for: 500 ms (v)"Go" tone delay (target foreperiod) =  350 ms TO 500 ms (v, random)Trial max duration =  5 seconds (v)♣ InstructionsInstructions emphasize speed and accuracy but not interlimb synchrony (for bimanual conditions). A loosely paraphrased instruction is as follows:                        | After the beep, move as quickly and accurately as you can to the target. Stop at the target.Participants are reminded to be quick and accurate from time to time throughout experimental session (approximately every 5 trials TO 10 trials.♣ FeedbackFeedback provided concerns the accuracy of the movement but not the speed. Speed is emphasized by the researcher verbally as)     | Try to go faster |    particularly in stroke survivors when slowing is especially noted.Augmented feedback is provided in the form of KR and KP,  which is available for 1 second (v) at movement end* after which the next trial begins.                 - diameter = 1 cm (v)                 - color = greenConcentric target circle:                 - diameter = 3 cm (v)                - color = 3 graded colors (see Figure 5 for gradations)                - distance =  5 cm (v) OR 15 cm (v)                - number of targets = 1 unit OR 2 units (v) (depending on Experimental Condition)Visual cursor representation of the position of the first proximal interphalangeal joint:                - diameter =  1 cm (v)                - color = black crosshair                - number of cursors = 1 Hz (depending on Condition)♣ TimelineHold cursor within start circle for: 500 ms (v)"Go" tone delay (target foreperiod) =  350 ms TO 500 ms (v, random)Trial max duration =  5 seconds (v)♣ InstructionsInstructions emphasize speed and accuracy but not interlimb synchrony (for bimanual conditions). A loosely paraphrased instruction is as follows:                        | After the beep, move as quickly and accurately as you can to the target. Stop at the target.Participants are reminded to be quick and accurate from time to time throughout experimental session (approximately every 5 trials TO 10 trials.♣ FeedbackFeedback provided concerns the accuracy of the movement but not the speed. Speed is emphasized by the researcher verbally as)     | Try to go faster |    particularly in stroke survivors when slowing is especially noted.Augmented feedback is provided in the form of KR and KP,  which is available for 1 second (v) at movement end* after which the next trial begins.                 - diameter = 3 cm (v)                - number of targets = 1 unit OR 2 units (v) (depending on Experimental Condition)Visual cursor representation of the position of the first proximal interphalangeal joint:                - diameter =  1 cm (v)                - color = black crosshair                - number of cursors = 1 Hz (depending on Condition)♣ TimelineHold cursor within start circle for: 500 ms (v)"Go" tone delay (target foreperiod) =  350 ms TO 500 ms (v, random)Trial max duration =  5 seconds (v)♣ InstructionsInstructions emphasize speed and accuracy but not interlimb synchrony (for bimanual conditions). A loosely paraphrased instruction is as follows:                        | After the beep, move as quickly and accurately as you can to the target. Stop at the target.Participants are reminded to be quick and accurate from time to time throughout experimental session (approximately every 5 trials TO 10 trials.♣ FeedbackFeedback provided concerns the accuracy of the movement but not the speed. Speed is emphasized by the researcher verbally as)     | Try to go faster |    particularly in stroke survivors when slowing is especially noted.Augmented feedback is provided in the form of KR and KP,  which is available for 1 second (v) at movement end* after which the next trial begins.                 - diameter =  1 cm (v)                - color = black crosshair                - number of cursors = 1 Hz (depending on Condition)♣ TimelineHold cursor within start circle for: 500 ms (v)"Go" tone delay (target foreperiod) =  350 ms TO 500 ms (v, random)Trial max duration =  5 seconds (v)♣ InstructionsInstructions emphasize speed and accuracy but not interlimb synchrony (for bimanual conditions). A loosely paraphrased instruction is as follows:                        | After the beep, move as quickly and accurately as you can to the target. Stop at the target.Participants are reminded to be quick and accurate from time to time throughout experimental session (approximately every 5 trials TO 10 trials.♣ FeedbackFeedback provided concerns the accuracy of the movement but not the speed. Speed is emphasized by the researcher verbally as)     | Try to go faster |    particularly in stroke survivors when slowing is especially noted.Augmented feedback is provided in the form of KR and KP,  which is available for 1 second (v) at movement end* after which the next trial begins. ♣ InstructionsInstructions emphasize speed and accuracy but not interlimb synchrony (for bimanual conditions). A loosely paraphrased instruction is as follows:                        | After the beep, move as quickly and accurately as you can to the target. Stop at the target.Participants are reminded to be quick and accurate from time to time throughout experimental session (approximately every 5 trials TO 10 trials.♣ FeedbackFeedback provided concerns the accuracy of the movement but not the speed. Speed is emphasized by the researcher verbally as)     | Try to go faster |    particularly in stroke survivors when slowing is especially noted.Augmented feedback is provided in the form of KR and KP,  which is available for 1 second (v) at movement end* after which the next trial begins.                         | After the beep, move as quickly and accurately as you can to the target. Stop at the target.Participants are reminded to be quick and accurate from time to time throughout experimental session (approximately every 5 trials TO 10 trials.♣ FeedbackFeedback provided concerns the accuracy of the movement but not the speed. Speed is emphasized by the researcher verbally as)     | Try to go faster |    particularly in stroke survivors when slowing is especially noted.Augmented feedback is provided in the form of KR and KP,  which is available for 1 second (v) at movement end* after which the next trial begins. ♣ FeedbackFeedback provided concerns the accuracy of the movement but not the speed. Speed is emphasized by the researcher verbally as)     | Try to go faster |    particularly in stroke survivors when slowing is especially noted.Augmented feedback is provided in the form of KR and KP,  which is available for 1 second (v) at movement end* after which the next trial begins. 1. Knowledge of Results (KR): Participants receive visual and auditory feedback regarding the accuracy of their hand position. KR feedback is provided in a graded manner with three levels as described below:2. Knowledge of Performance (KP): Veridical cursor position is visible at movement end as a red dot.A schematic representation of the trial set up for each trial is shown below:
10 points (f): if hand position is at the center of the target3 points (f): if hand position is within the second concentric target circle (= diameter x 2)1 point (f): if hand position is within the third concentric target circle (= diameter x 3)
IMPORTANT NOTE: During acquisition, real-time velocity is computed by the Kinereach software and movement end is  defined programmatically as velocity of hand
10 points (f): if hand position is at the center of the target3 points (f): if hand position is within the second concentric target circle (= diameter x 2)1 point (f): if hand position is within the third concentric target circle (= diameter x 3)
?. [Experimental Conditions]
EXPERIMENTAL CONDITIONSThe participant will perform a rapid reaching motion toward a concentric target circle 20 times in unimanual and bimanual conditions (80 trials, excluding practice trials)
?. [Apparatus]
KINEREACH® KINEMATIC DATA COLLECTION SYSTEMThe Kinereach system comprises of a glass table-top, a 60 in (f) flat-screen high-definition display witha mirror virtualization (which is 35 cm (f) above the table surface) and blocks the direct vision of the arms and hands.a trakSTAR electromagnetic motion tracking system (Ascension Technology) consisting of 4 sensors (f) providing 20 DoF (f) measurement of upper limb movementswith a sampling rate of 116 Hz (v, range: 100-200)two air sleds (one for each upper limb) that use a compressed air delivery mechanism to enable zero-gravity, minimal friction movements, a height-, tilt-, and distance-adjustable chair with trunk support, and an iMac computer installed with the Kinereach support software
?. [Code & Task Simulation]
Code to Generate Session Files and Example Session Files for KineReachIf you plan to use the Kinereach Kinematic Data Collection Device to reproduce this experiment, you will need a target file, a trial session file and a target session file to specify the above-described parameters.You can access our MATLAB code to generate these files on your own OR use an example set on GitHub here:https://github.com/rinivarg/kr-exptsTask Simulation Video
?. [General Setup]
GENERAL SETUPParticipants are seated comfortably on an adjustable chair facing the table. Chair PositionSecured the participant to the chair using a horizontal harness across the waist.Strap a vertical harness around each shoulder to secure the torso in the upright position. Chair Height AdjustmentAdjust the height of the chair using the lever below so the virtualization mirror is at participant's chin level.Ask whether the target display is visible to participants                                        | Are you able to see most of the screen?Chair Distance AdjustmentCarefully push the chair inward until the participant can comfortably place both arms at shoulder height on the table. Lock the chair in place.Ensure that the participant's legs do not move the transmitter located under the table.Participants rest their feet on a small wooden step stool beneath the table.Sensors & Sensor PlacementsFour Ascension TrakStar electromagnetic sensors were used for the current experiment.  They were secured using adhesive tape and a soft pre-wrap at the following locations on the upper extremity :    Sensor 1: the dorsum of the left hand on the second metacarpal (as close in line to the middle finger as possible)Sensor 2: the mid-upper left arm Sensor 3: the dorsum of the right hand on the second metacarpal (as close in line to the middle finger as possible)Sensor 4: to the mid-upper right arm   Note that only Sensors 1 and 3 are required to conduct this experiment. Sensors 2 and 4, however, allow real-time inverse kinematic computations of joint angles which will be outputted on the data text file. In order to do this, follow the below calibration/digitization routine:  Arm Position on Air Sled System   Instruct the participant to rest their thumb in the groove and align their forearm with the air sled. Secure each arm to the sled with the velcro straps without cutting off the airway of the tube. The intial position of the elbow is 70-80 degrees flexion and the shoulder is 20-30 degrees horizontoal abduction.  The start circle/s are 25 cm from the edge of the table and 24 cm apart. Chair Height AdjustmentAdjust the height of the chair using the lever below so the virtualization mirror is at participant's chin level.Ask whether the target display is visible to participants                                        | Are you able to see most of the screen?Chair Distance AdjustmentCarefully push the chair inward until the participant can comfortably place both arms at shoulder height on the table. Lock the chair in place.Ensure that the participant's legs do not move the transmitter located under the table.Participants rest their feet on a small wooden step stool beneath the table.Sensors & Sensor PlacementsFour Ascension TrakStar electromagnetic sensors were used for the current experiment.  They were secured using adhesive tape and a soft pre-wrap at the following locations on the upper extremity :    Sensor 1: the dorsum of the left hand on the second metacarpal (as close in line to the middle finger as possible)Sensor 2: the mid-upper left arm Sensor 3: the dorsum of the right hand on the second metacarpal (as close in line to the middle finger as possible)Sensor 4: to the mid-upper right arm   Note that only Sensors 1 and 3 are required to conduct this experiment. Sensors 2 and 4, however, allow real-time inverse kinematic computations of joint angles which will be outputted on the data text file. In order to do this, follow the below calibration/digitization routine:  Arm Position on Air Sled System   Instruct the participant to rest their thumb in the groove and align their forearm with the air sled. Secure each arm to the sled with the velcro straps without cutting off the airway of the tube. The intial position of the elbow is 70-80 degrees flexion and the shoulder is 20-30 degrees horizontoal abduction.  The start circle/s are 25 cm from the edge of the table and 24 cm apart.                                     | Are you able to see most of the screen?Chair Distance AdjustmentCarefully push the chair inward until the participant can comfortably place both arms at shoulder height on the table. Lock the chair in place.Ensure that the participant's legs do not move the transmitter located under the table.Participants rest their feet on a small wooden step stool beneath the table.Sensors & Sensor PlacementsFour Ascension TrakStar electromagnetic sensors were used for the current experiment.  They were secured using adhesive tape and a soft pre-wrap at the following locations on the upper extremity :    Sensor 1: the dorsum of the left hand on the second metacarpal (as close in line to the middle finger as possible)Sensor 2: the mid-upper left arm Sensor 3: the dorsum of the right hand on the second metacarpal (as close in line to the middle finger as possible)Sensor 4: to the mid-upper right arm   Note that only Sensors 1 and 3 are required to conduct this experiment. Sensors 2 and 4, however, allow real-time inverse kinematic computations of joint angles which will be outputted on the data text file. In order to do this, follow the below calibration/digitization routine:  Arm Position on Air Sled System   Instruct the participant to rest their thumb in the groove and align their forearm with the air sled. Secure each arm to the sled with the velcro straps without cutting off the airway of the tube. The intial position of the elbow is 70-80 degrees flexion and the shoulder is 20-30 degrees horizontoal abduction.  The start circle/s are 25 cm from the edge of the table and 24 cm apart. Sensors & Sensor PlacementsFour Ascension TrakStar electromagnetic sensors were used for the current experiment.  They were secured using adhesive tape and a soft pre-wrap at the following locations on the upper extremity :    Sensor 1: the dorsum of the left hand on the second metacarpal (as close in line to the middle finger as possible)Sensor 2: the mid-upper left arm Sensor 3: the dorsum of the right hand on the second metacarpal (as close in line to the middle finger as possible)Sensor 4: to the mid-upper right arm   Note that only Sensors 1 and 3 are required to conduct this experiment. Sensors 2 and 4, however, allow real-time inverse kinematic computations of joint angles which will be outputted on the data text file. In order to do this, follow the below calibration/digitization routine:  Arm Position on Air Sled System   Instruct the participant to rest their thumb in the groove and align their forearm with the air sled. Secure each arm to the sled with the velcro straps without cutting off the airway of the tube. The intial position of the elbow is 70-80 degrees flexion and the shoulder is 20-30 degrees horizontoal abduction.  The start circle/s are 25 cm from the edge of the table and 24 cm apart. Note that only Sensors 1 and 3 are required to conduct this experiment. Sensors 2 and 4, however, allow real-time inverse kinematic computations of joint angles which will be outputted on the data text file. In order to do this, follow the below calibration/digitization routine:Arm Position on Air Sled System Instruct the participant to rest their thumb in the groove and align their forearm with the air sled. Secure each arm to the sled with the velcro straps without cutting off the airway of the tube. The intial position of the elbow is 70-80 degrees flexion and the shoulder is 20-30 degrees horizontoal abduction.  The start circle/s are 25 cm from the edge of the table and 24 cm apart.
If the KINEREACH is used, the following calibration routine is followed:  Reference sensor (sensor 2) is placed on anatomical landmarks in the below specified order:  ABC1Anatomical LandmarksKey to be pressed to calibrate for Left HandKey to be pressed to calibrate for Right Hand22nd metacarpalF113Between 2nd and 3rd metacarpalF224Below “snuff box” (medial [inside] side of wrist)F335Below styloid process of ulna (lateral [outer] side of wrist)F446Medial epicondyle of elbow (bump on lower side of elbow)F557Lateral epicondyle of elbow (bump on top side of elbow)F668Acromion process (lateral to where the clavicle and scapula meet)F779After placing Sensor 2 on left upper arm (mid)-8NOTE: For the current bilateral experiment, both limbs are calibrated/digitized with left arm first followed by right arm.
Note the following safety and validation measures when setting up in Kinereach :The TrakStar is an electromagnetic system and even though it has a relatively small magnetic field, ensure that the participants do not have metal implants or pacemakers. To avoid the wires from getting tangled, position the wire along the arm.The purpose of the soft pre-wrap is to keep the sensors from moving during the experiment. However, if too tight it may cut off circulation. Ask the participant if the wrapping is too tight. If it is, then redo the wrapping.Ensure that the participant remains still during calibration for accuracy. Check the arm and elbow angles to ensure they are correct. It’s easiest to check elbow at 90 degrees and arm 0 degrees.
Important steps to check: Air flow must be turned on. Check for pressure to be set to 13 psi (v). May vary from device to device. Ask participant to confirm air flow is even between hands and smooth (without interruptions). Turn on the HDTV. Turn on the trackSTAR box by flipping on the switch located on the back. Turn on computer.
?. [Abbreviations]
f = fixedv = variable (random value or range of values is specified alongside)DoF = degrees of freedompsi = pounds per square inch (units of pressure)