Support for this research was provided by the University of Maryland Kinesiology Graduate Research Initiative Fund to Yue Du.

The protocol was performed in accordance with the guidelines approved by the Institutional Review Board at the University of Maryland, College Park.
1. Experimental Set-up
<ol>
	<li>Set up a motion capture system as shown in Figure 1a. Place eight cameras in a circle with a radius of 4 m. 
	NOTE: The number and positions of cameras can be varied, provided all cameras are appropriately positioned to obtain a clear vision of all reflective markers attached to...

<ol>
	<li>Nissen, M. J., Bullemer, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Attentional+requirements+of+learning:+Evidence+from+performance+measures.">Attentional requirements of learning: Evidence from performance measures.</a> Cognit Psychol. 19 (1), 1-32 (1987).</li><li>Willingham, D. B., Nissen, M. J., Bullemer, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+development+of+procedural+knowledge.">On the development of procedural knowledge.</a> J Exp Psychol Learn Mem Cogn. 15 (6), 1047-1060 (1989).</li><li>Du, Y., Valentini, N. C., Kim, M. J., Whitall, J., Clark, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Children+and+adults+both+learn+motor+sequences+quickly,+but+do+so+differently.">Children and adults both learn motor sequences quickly, but do so differently.</a> Front Psychol. 8 (158), (2017).</li><li>Du, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Learning processes underlying implicit motor sequence acquisition in children and adults. , (2016).</li><li>Du, Y., Clark, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+insights+into+statistical+learning+and+chunk+learning+in+implicit+sequence+acquisition.">New insights into statistical learning and chunk learning in implicit sequence acquisition.</a> Psychon Bull Rev. , 1-9 (2016).</li><li>Gheysen, F., Van Waelvelde, H., Fias, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impaired+visuo-motor+sequence+learning+in+Developmental+Coordination+Disorder.">Impaired visuo-motor sequence learning in Developmental Coordination Disorder.</a> Res Dev Disabil. 32 (2), 749-756 (2011).</li><li>Wilson, P. H., Maruff, P., Lum, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Procedural+learning+in+children+with+developmental+coordination+disorder.">Procedural learning in children with developmental coordination disorder.</a> Hum Movement Sci. 22 (4-5), 515 (2003).</li><li>Cermak, S. A., Larkin, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Developmental coordination disorder. , (2002).</li><li>Taylor, J. A., Ivry, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Implicit+and+explicit+processes+in+motor+learning.">Implicit and explicit processes in motor learning.</a> Action science. , 63-87 (2013).</li><li>Moisello, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+serial+reaction+time+task+revisited:+a+study+on+motor+sequence+learning+with+an+arm-reaching+task.">The serial reaction time task revisited: a study on motor sequence learning with an arm-reaching task.</a> Exp Brain Res. 194 (1), 143-155 (2009).</li><li>Song, J. H., Nakayama, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hidden+cognitive+states+revealed+in+choice+reaching+tasks.">Hidden cognitive states revealed in choice reaching tasks.</a> Trends Cogn Sci. 13 (8), 360-366 (2009).</li><li>Marcus, D. J., Karatekin, C., Markiewicz, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oculomotor+evidence+of+sequence+learning+on+the+serial+reaction+time+task.">Oculomotor evidence of sequence learning on the serial reaction time task.</a> Mem Cognition. 34 (2), 420-432 (2006).</li><li>Shanks, D. R., Johnstone, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluating+the+relationship+between+explicit+and+implicit+knowledge+in+a+sequential+reaction+time+task.">Evaluating the relationship between explicit and implicit knowledge in a sequential reaction time task.</a> J Exp Psychol Learn Mem Cogn. 25 (6), 1435-1451 (1999).</li><li>Destrebecqz, A., Peigneux, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+studying+unconscious+learning.">Methods for studying unconscious learning.</a> Prog Brain Res. 150, 69-80 (2005).</li><li>Massion, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Movement,+posture+and+equilibrium:+interaction+and+coordination.">Movement, posture and equilibrium: interaction and coordination.</a> Prog Neurobiol. 38 (1), 35-56 (1992).</li><li>MacKinnon, C. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+anticipatory+postural+adjustments+prior+to+stepping.">Preparation of anticipatory postural adjustments prior to stepping.</a> J Neurophysiol. 97 (6), 4368-4379 (2007).</li><li>Cordo, P. J., Nashner, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Properties+of+postural+adjustments+associated+with+rapid+arm+movements.">Properties of postural adjustments associated with rapid arm movements.</a> J Neurophysiol. 47 (2), 287-382 (1982).</li><li>Vicon Motion System Nexus Documentation. Available from: <a target="_blank" href="https://docs.vicon.com/display/Nexus25/Nexus+Documentation">https://docs.vicon.com/display/Nexus25/Nexus+Documentation</a> (2017)</li><li>Oldfield, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+assessment+and+analysis+of+handness:+The+edinburgh+inventory.">The assessment and analysis of handness: The edinburgh inventory.</a> Neuropsychologia. 9, 97-113 (1971).</li><li>Armstrong, T., Bull, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+the+world+health+organization+global+physical+activity+questionnaire+(GPAQ).">Development of the world health organization global physical activity questionnaire (GPAQ).</a> J Public Health. 14 (2), 66-70 (2006).</li><li>Henderson, S. E., Sugden, D. A., Barnett, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Movement Assessment Battery for Children - Second edition (Movement ABC-2). , (2007).</li><li>Destrebecqz, A., Cleeremans, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Can+sequence+learning+be+implicit?+New+evidence+with+the+process+dissociation+procedure.">Can sequence learning be implicit? New evidence with the process dissociation procedure.</a> Psychon Bull Rev. 8 (2), 343-350 (2001).</li><li>De Leva, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adjustments+to+Zatsiorsky-Seluyanov's+segment+inertia+parameters.">Adjustments to Zatsiorsky-Seluyanov's segment inertia parameters.</a> J Biomech. 29 (9), 1223-1230 (1996).</li><li>Bair, W. -. N., Kiemel, T., Jeka, J. J., Clark, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+multisensory+reweighting+for+posture+control+in+children.">Development of multisensory reweighting for posture control in children.</a> Exp Brain Res. 183 (4), 435-446 (2007).</li><li>Curran, T., Keele, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Attentional+and+nonattentional+forms+of+sequence+learning.">Attentional and nonattentional forms of sequence learning.</a> J Exp Psychol Learn Mem Cogn. 19 (1), 189-202 (1993).</li><li>Du, Y., Prashad, S., Schoenbrun, I., Clark, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probabilistic+motor+sequence+yields+greater+offline+and+less+online+learning+than+fixed+sequence.">Probabilistic motor sequence yields greater offline and less online learning than fixed sequence.</a> Front Hum Neurosci. 10, (2016).</li><li>Destrebecqz, A., Cleeremans, A., Jim&#233;nez, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Attention and implicit learning. , 181-213 (2003).</li><li>Jimenez, L., Vazquez, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sequence+learning+under+dual-task+conditions:+alternatives+to+a+resource-based+account.">Sequence learning under dual-task conditions: alternatives to a resource-based account.</a> Psychol Res. 69 (5-6), 352-368 (2005).</li><li>Curran, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+aging+on+implicit+sequence+learning:+Accounting+for+sequence+structure+and+explicit+knowledge.">Effects of aging on implicit sequence learning: Accounting for sequence structure and explicit knowledge.</a> Psychol Res. 60 (1-2), 24-41 (1997).</li><li>Ramenzoni, V. C., Riley, M. A., Shockley, K., Chiu, C. Y. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Postural+responses+to+specific+types+of+working+memory+tasks.">Postural responses to specific types of working memory tasks.</a> Gait Posture. 25 (3), 368-373 (2007).</li><li>Riley, M. A., Baker, A. A., Schmit, J. M., Weaver, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+visual+and+auditory+short-term+memory+tasks+on+the+spatiotemporal+dynamics+and+variability+of+postural+sway.">Effects of visual and auditory short-term memory tasks on the spatiotemporal dynamics and variability of postural sway.</a> J Mot Behav. 37 (4), 311-324 (2005).</li><li>Stins, J. F., Michielsen, M. E., Roerdink, M., Beek, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sway+regularity+reflects+attentional+involvement+in+postural+control:+Effects+of+expertise,+vision+and+cognition.">Sway regularity reflects attentional involvement in postural control: Effects of expertise, vision and cognition.</a> Gait Posture. 30 (1), 106-109 (2009).</li><li>Nougier, V., Vuillerme, N., Teasdale, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+a+reaction+time+task+on+postural+control+in+humans.">Effects of a reaction time task on postural control in humans.</a> Neurosci. Lett. 291 (2), 77-80 (2000).</li><li>Robertson, E. 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The authors have nothing to disclose.

This protocol describes the experimental set-up and procedures for a modified SRT task. The modified SRT task shares its appealing simplicity with the classic SRT task, although the modified SRT task demands use of a motion capture technique. Like the classic SRT task, many parameters could be manipulated for specific research questions in the foot-stepping SRT task, including but not limited to: the length of interval-stimulus interval or response-stimulus interval27, the type of sequence structu...

Implicit motor sequence learning, generally known as learning a sequence without knowing the sequence, is critical to our daily activities and has been well studied by a paradigmatic task named the serial reaction time (SRT) task designed by Nissen and Bullemer1. In this classic SRT task, participants press keys to respond quickly and accurately to visual stimuli. To examine sequence learning, the appearance of visual stimuli is manipulated to follow either a pre-structured or random sequence, which is unknown to participants. Learning is evidenced by the faster response time to the pre-structured sequence (e.g., the training sequence) than that to the random or another pre-structured sequence1,2. While the classic SRT task typically requires bi-manual finger tapping, a vast majority of implicit motor sequence learning in everyday activities, such as dancing, playing musical instruments, or playing sports, involves whole body actions that present postural and inertial challenges not found in the classic SRT task. Thus, we proposed that sequence learning tasks need to be more multifaceted. In addition, the focus of the previous research has been almost exclusively on the cognitive component of the task (e.g., decision making or action selection), ignoring the motor control issues involved in sequence learning (e.g., movement execution). Thus, to further understand implicit motor sequence learning, it is essential to study sequence learning in a whole-body or gross motor task that better approximates our daily motor activities.
In our recent studies, we extended the classic SRT task to a modified SRT task where finger pressing was replaced by foot stepping to incorporate postural control into sequence learning3,4,5. This modified task presents its own advantages to complement the classic SRT task. First, the gross motor sequence learning task better mimics daily sequential activities where whole-body movement is involved. To date, our understanding of motor sequence learning typically comes from the classic SRT task, but little is known whether the knowledge of motor sequence learning from the classic SRT task remains to be true in learning sequential motor skills in daily activities. Thus, the modified SRT task allows us to examine whether the systematically reported characteristics (e.g., age-independent implicit sequence learning between children and adults) in the finger-pressing SRT task remain when postural control is involved. Additionally, in populations with posture control and gross motor skill learning difficulties, such as children with developmental coordination disorder6,7,8, understanding how posture control interacts with gross motor sequence learning is critical to help improve intervention strategies, and thus optimize the effectiveness of learning sequential motor skills in daily life.
Second, a common notion about implicit sequence learning is that motor planning, and not movement execution, plays an important role in learning a sequence in the classic SRT task9. This is because pressing keys does not involve moving to new locations in space, as the fingers are always on the response keys. However, many daily sequential behaviors involve large spatial movements. Little is known as to whether movement execution is a key player in motor sequence learning when large spatial movements are required. In the classic SRT task, response time, the summation of reaction time (RT) and movement time (MT), serves as an indicator of sequence learning. The foot-stepping SRT task, like other paradigms involving spatial movements10, allows the researcher to disentangle response time in implicit sequence learning into RT, which reflects cognitive processing, and MT, which characterizes the movement itself.
Third, in addition to MT, the combination of the foot-stepping SRT task and motion capture techniques provides rich data on the continuous whole-body movement (e.g., movement of the center of mass, or COM). Measuring the continuous change of movement has the advantage of revealing the dynamics of the cognitive processes underlying the discrete response measured by RT or MT11,12. In particular, learning sequences in the SRT task are typically explained as a mixture of explicit and implicit processes. That is, despite the common use of the SRT task as an implicit learning task, participants often show the capability to verbally recall the learned sequence after the SRT task, suggesting an explicit component involved in implicit sequence learning. Although the explicit component can be assessed by recall tests conducted after the SRT task13,14, these post-task tests lack the ability to examine the temporal evolution of explicit knowledge during learning. We propose that with explicit sequence knowledge, an individual would know the location of the next stimulus, and thus produce anticipatory postural adjustment15,16,17 in a feedforward manner to prepare for the stepping foot to move to the corresponding target. Therefore, examining the movement of the COM before the stimulus appearance (i.e., anticipation) opens a window to studying the progressive development of explicit memory during implicit sequence learning.
The protocol demonstrates the experimental set-up and procedure of the foot-stepping SRT task. We provide representative results of response time, RT, and MT. In addition, we present results regarding the relationship between posture control and the explicit processes underlying implicit motor sequence learning.

<table>
	<tbody>
		<tr>
			<td>Vicon motion capture system</td>
			<td>Vicon</td>
			<td>Vicon T-40, T-160, calibration wand</td>
			<td>Alternative systems may be used</td>
		</tr>
		<tr>
			<td>50 mm reflective markers</td>
			<td>Vicon</td>
			<td>N/A</td>
			<td>Numbers of markers may be varied</td>
		</tr>
		<tr>
			<td>Labview software</td>
			<td>National Instruments</td>
			<td>N/A</td>
			<td>Control visual stimuli. Use together with DAQ board. Alternative software may be used</td>
		</tr>
		<tr>
			<td>DAQ board</td>
			<td>National Instruments</td>
			<td>BNC-2111; DAQCard-6024E</td>
			<td></td>
		</tr>
		<tr>
			<td>MATLAB</td>
			<td>MathWorks</td>
			<td>N/A</td>
			<td>Alternative software may be used</td>
		</tr>
		<tr>
			<td>double sided hypo-allergenic adhesive tape</td>
			<td></td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>pre-wrapping tape</td>
			<td></td>
			<td>N/A</td>
			<td></td>
		</tr>
	</tbody>
</table>

the "motor" in implicit motor sequence learning: a foot-stepping serial reaction time task

This protocol describes a modified serial reaction time (SRT) task used to study implicit motor sequence learning. Unlike the classic SRT task that involves finger-pressing movements while sitting, the modified SRT task requires participants to step with both feet while maintaining a standing posture. This stepping task necessitates whole body actions that impose postural challenges. The foot-stepping task complements the classic SRT task in several ways. The foot-stepping SRT task is a better proxy for the daily activities that require ongoing postural control, and thus may help us better understand sequence learning in real-life situations. In addition, response time serves as an indicator of sequence learning in the classic SRT task, but it is unclear whether response time, reaction time (RT) representing mental process, or movement time (MT) reflecting the movement itself, is a key player in motor sequence learning. The foot-stepping SRT task allows researchers to disentangle response time into RT and MT, which may clarify how motor planning and movement execution are involved in sequence learning. Lastly, postural control and cognition are interactively related, but little is known about how postural control interacts with learning motor sequences. With a motion capture system, the movement of the whole body (e.g., the center of mass (COM)) can be recorded. Such measures allow us to reveal the dynamic processes underlying discrete responses measured by RT and MT, and may aid in elucidating the relationship between postural control and the explicit and implicit processes involved in sequence learning. Details of the experimental set-up, procedure, and data processing are described. The representative data are adopted from one of our previous studies. Results are related to response time, RT, and MT, as well as the relationship between the anticipatory postural response and the explicit processes involved in implicit motor sequence learning.

The above paradigm is implemented by Du and colleagues in a series of studies3,4,5. We use a part of data adopted from one of these studies4 to represent the usage of the foot-stepping SRT task. In this study, there are 6 learning blocks and a RSI of 700 ms is used. Visual stimuli followed sequence A (i.e., 1423564215; Figure 1a) in b...

Watch this Scientific Journal Video about The "Motor" in Implicit Motor Sequence Learning: A Foot-stepping Serial Reaction Time Task at JoVE.com

The &quot;Motor&quot; in Implicit Motor Sequence Learning: A Foot-stepping Serial Reaction Time Task

We introduce the foot-stepping serial reaction time (SRT) task. This modified SRT task, complementing the classic SRT task that involves only finger-pressing movement, better approximates daily sequenced activities and allows researchers to study the dynamic processes underlying discrete response measures and disentangle the explicit process operating in implicit sequence learning.

The "Motor" in Implicit Motor Sequence Learning: A Foot-stepping Serial Reaction Time Task

This protocol describes a modified serial reaction time (SRT) task used to study implicit motor sequence learning. Unlike the classic SRT task that ...

The overall goal of this experiment is to study how people learn a sequence of actions that mimic daily activities, and to elucidate the cognitive processes, specifically the explicit process operating an implicit motor sequence learning. This task provides a novel way to review the progress of development of the explicit wellness during implicit motor sequence learning. Using this task can help answer key questions in the motor learning and the developmental field, such as implicit motor sequence learning and its age-related development.The key advantage of this technique is that compared to the classic SRT task, the foot-stepping in task involves greater motor control complexity and it allows us to better understand the learning of sequential skills in daily life, such as dancing, playing musical instruments, or playing sports. The implications of this technique extend to helping us understand children with movement difficulties, particularly the learning of motor sequences by children with something called developmental coordination disorder or DCD. We had first got the idea for this method when we watched one of our children, who we were studying, who had DCD, as he practiced the Wii game, Dance Dance Revolution"He was able to learn the sequence, despite the problems he was having with his motor control and his postural challenges.Demonstrating the procedural will be Elizabeth Bell and Mia Caminita, graduate students from the neuromechanics laboratory. Begin by insuring proper function of the motion capture system to ensure accurate collection of 3D data from reflective markers. For dynamic calibration, wave the calibration wand supplied with the motion capture system through the space where all reflective markers would move when participants perform the SRT task.For static calibration, place the calibration wand on the floor with the position and orientation, which can be used as the origin of the coordination system of the motion capture system. Run the motion capture system to set the origin. In the motion capture system, assign each marker a name and create segments by connecting markers together.Link all segments to finalize the skeleton template. Upon arrival, ask participants to carefully read and sign the consent form. Hi Mia, thanks for volunteering to complete this study.This consent form will give you better detail on exactly what we're going to do today. If you will agree to participate, can you just initial each page and then sign the last? After this, there's just a few questionnaires that we will go through.Screen for study eligibility using such questionnaires as the hand dominance questionnaire, global physical activity level questionnaire, and neurological health questionnaire. Ask the participant to take off their shoes and socks. Okay, great, now we're ready for motion capture.If I could just have you take off your shoes and socks, we'll be good to go.Okay. Then use double-sided, hypoallergenic, adhesive tape and pre-wrapping tape to attach 38 spherical reflective markers, each 50 millimeters in diameter, to the skin at predetermined significant bony landmarks. This marker setup is the same as the customized skeleton template shown here.Clear all unwanted reflections other than those 38 markers from the participant's body. Run a calibration trial by instructing participants to stand quietly on the home position in a T-pose and run the motion capture system to capture all markers for two to ten seconds. Before each participant starts the task, set up the parameters, including but not limited to, participant ID, group ID, number of learning blocks, the time length of stimulus presentation, and the interstimulus interval or response stimulus interval, to control the time interval between the completion of movement and the onset of the next stimulus.Ask the participant to stand on the home position. Okay, if you could step into the dark blue rectangles, this will be your home position. And adjust the distance of the home position so that participants can comfortably step on to all six targets on the floor.Have the participant quickly step on to each target several times. And back behind your left foot, great. And mark the distance from the home position to each target at the most comfortable stepping length for each participant.Tell the participant that once a stimulus appears at one of six locations shown on the monitor, they need to step as quickly and accurately as possible to the corresponding target on the floor and then return to the home position. Once the stimulus appears at one of the six locations shown on the monitor, you will step as quickly and accurately as possible to the corresponding target on the floor and then return to the home position. Then, tell the participant to step with the right foot to the three targets located on the right side and the left foot to the other three targets.You will step with your right foot for the three targets on the right side of the screen and your left foot for the three targets on the left. Instruct the participants to keep their elbows by their side and bent at a 90 degree angle when they perform the task so that the cameras can see the markers placed on the hip. Please keep your hands by your side and your elbows bent at a 90 degree angle.Run a practice block that consist of 36 steps so that participants are familiar with the task. Stimuli on this block appear in random order. After the practice block, start the experimental blocks.In this protocol, there are six blocks, and each experimental block is comprised of 100 steps per stimulus. Set the specific order of visual stimuli as per experimental purposes. Stimuli follow either a specified or random sequence.The presentation of stimulus order is unknown to participants. Give participants a mandatory three minute break after each block. Before each experimental block, remind participants to respond to stimuli as quickly and accurately as they can.So we're going to repeat the same task. It's important to respond to stimuli as quickly and accurately as you can. Given a possible speed accuracy trade-off, instructing the subject to be as fast and accurate as possible, at the same time before each learning block is critical.Upon completion of all learning blocks, ask participants to complete a post-test that consists of widely used recall and recognition tests described in the literature. This figure illustrates 12 young adults'mean response times across six learning blocks. The response time to a novel sequence is significantly lower in block five compared with the learned sequence in block four, indicating learning of the sequence.Mean reaction time exhibits the same pattern as response time. In particular, reaction time in block five is slower than that in block four. Unlike response time and reaction time, movement time is comparable between blocks four and five.In addition to the time measurement focused in the classic SRT task, the whole body movement, especially the center of mass movement, can also be measured in the foot-stepping SRT task. This figure shows one participant's data of movement trajectories of the center of mass that occur 100 milliseconds before the stimuli appear. This figure shows the directions of the anticipatory center of mass movement.The anticipatory movement direction for each stimulus is very inconsistent at the beginning and became more consistent as learning progressed across blocks. This figure shows the significant changes in the movement direction variability across blocks at the group level. Specifically, the variability increased from block four to five, indicating that the center of mass movement direction would be an evident sign of motor sequence learning in the SRT task.More importantly, the anticipatory center of mass movement is likely to reflect the explicit process operating in implicit motor sequence learning. The increased variability from block four to five was demonstrated only in participants who required the explicit knowledge of the sequence, but not in participants who did not show explicit knowledge. Moreover, the change in variability from block four to five is significantly correlated to the amount of explicit knowledge acquired by participants.After watching this video, you should have a good understanding of the advantages of this foot-stepping task, that compliment the classic key-pressing SRT task. First, it better mimics impulse sequence learning in daily sequenced activities. Second, this modified SRT task offers a unique ability to examine the temporal evolution of explicit awareness that operates in implicit motor sequence learning.Last, using this tasks, other information, like continuous movement trajectories, can be recorded and examined. The measurement of temporal dynamics of movement could be used to review hidden cognitive process in future sequence learning studies.

the-motor-implicit-motor-sequence-learning-foot-stepping-serial

Research

JoVE Journal

Behavior

8.4K 조회수.  University of Maryland, College Park. The overall goal of this experiment is to study how people learn a sequence of actions that mimic daily activities, and to elucidate the cognitive processes, specifically the explicit process operating an implicit motor sequence learning. This task provides a novel way to review the progress of development of the explicit wellness during implicit motor sequence learning. Using this task can help answer key questions in the motor learning and the developmental field, such as implicit motor seq...