Introduction to Motor Control and Learning, KNES 251, University of Calgary PDF

Introduction to Motor Control and Learning Taxonomy and Properties of Human Movements KNES 251 Introduction to Motor Control and Learning University of Calgary October 21, 2024 Humans can perform a remarkable range of motor skills...

Introduction to Motor Control and Learning Taxonomy and Properties of Human Movements KNES 251 Introduction to Motor Control and Learning University of Calgary October 21, 2024 Humans can perform a remarkable range of motor skills We can apply a taxonomy to understand different types of motor skills, their functional properties and types of processing they require.  D Lecture Objectives 1. Understand the difference between gross and fine motor skills. 2. Understand the difference between closed and open motor skills. 3. Understand the difference between discrete, serial, and continuous motor skills. 4. Understand basic properties and processes involved in goal-directed arm movements. “Take home” message: Humans can perform a range of motor skills. These skills can be classified into different functional categories so we can study and understand them. Fine Motor Skills small & precise Fine motor skills involve the use of small muscles of the hands, fingers , toes, wrists, lips and tongue to perform small, precise movements. They involve small movements with high accuracy demands. Some examples include threading a needle, picking up a coin, etc.  muscle groups Gross Motor Skills large , require larger Gross motor skills are large movements that require the use of large muscles in the arms, legs, torso and feet. w/ example fingers moving = fine example wi limbs many moving = gross They involve large movements (often involving the whole body). Some examples include walking, standing up from a seated position, reaching to open a door.  Open Motor Skills In an open motor skill the environment is variable and unpredictable. Playing football Playing hockey They require continuous evaluation of task and environmental demands. Some examples include football, hockey, tennis, badminton, etc.  Closed Motor Skills In a closed motor skill the environment is stable and predictable. Running on a closed track Swimming in an assigned lane Performer can evaluate environmental demands and prepare motor actions in advance. Some examples include running a marathon, swimming, etc.  Continuum of Environmental Demands Closed Motor Skills Open Motor Skills Motor skills lie on a continuum between open and closed based on differences in the task and/or environmental demands.  * know all diff - types Discrete Motor Skills of skills be able to , give an example of each Discrete motor skills are typically brief actions with a well- defined beginning and end. Discrete motor skills are important component of sports and daily life.  sequence of the same skill Continuous Motor Skills over a over again Continuous motor skills are repetitive and often cyclical with no clear beginning or end. min continuously doing it for a long period of time Performer can adjust the speed of movement. Serial Motor Skills take & a bunch of discrete motor skills put them together Serial motor skills are composed of a group of discrete skills strung together to make up a new, more complicated skill. Many activities of daily living would be classified as serial motor skills (e.g., pouring a glass of milk, taking a sip from your coffee, etc.). They are performed by assembling discrete motor skills into a functional sequence.  Continuum of Task Demands Discrete Motor Skills Serial Motor Skills Continuous Motor Skills cyclingto /I The Sophistication of the Voluntary Motor System Reaching to a target in the environment We are going to focus on basic properties of reaching movements. How do we make accurate reaching movements? Reach for a glass of milk There are many different ways to reach the glass Possible hand paths Hand paths tend to be smooth and straight. have unless we obstacles How do we choose, plan, and control a movement to reach the glass and what does this tell us about the control of arm movements?  perturb-> change or disturb motion How can we measure and understand movements? helps model person after movements End Reach from the Cameras and reflective markers Task start to end - allows for more movement compared target in a fixed to kin arm. Start time Hand Motion Profile ① shows changes in distance overtime End Target Movement initiation Robotics we can apply forces to 2 cm Start Target somebody We can use different techniques to record * Hand Speed Profile - shows of velocity movement and understand Peak Velocity overtime movement. Hand leaves Hand enters start position end target half acceleration 5 half deccelerate cm/s  Invariant features of upper limb movements 10-45% of time = acceleration Hand paths 50-55-1. of time Upper limb movements - deceleration tend to be smooth, Legend Target 30 cm relatively straight and 20 cm Hand velocities accurate with ‘bell- 10 cm afferent :· ↓ shaped’ velocity 5 cm as we age , less sensory : deceleration & 2.5 cm info abt where you are in space profiles collagen also degrades affecting sensory The shape of inpot speed profiles is ~constant across movement Start amplitudes. Adapted from (Gordon et al., 1984) peak if reaching further dist- velocity-higher to Stereotyped features of reaching movements suggest the motor system explicitly plans and maintains the limb’s trajectory. un patte Invariant features of upper limb movements Legend Hand Speeds Target 30 cm 20 cm 10 cm 5 cm 2.5 cm Similar speed and acceleration profiles across movement Acceleration Profiles amplitudes. * know what it looks like Start Start Stop Adapted from (Gordon et al., 1984) Similar scaling noted in hand acceleration profiles. Normalizing hand speeds and accelerations in time produces near identical profiles. Invariant features of upper limb movements measures total displacement of hand piece Behavioural Task Hand Paths wh moving angle when change of distance movement Movement times were constant and participants were implicitly required to Adapted from Morasso (1981) scale their hand speed (and acceleration) profiles. Participants made target-directed reaching movements while grasping the handle of a robotic manipulandum. Kandel et al. (2016) Principles in Neural Science  Invariant features of upper limb movements Exemplar Subject Data Behavioural Task Acc. Dec. Acc. Dec. Acc. Dec. Time Time Time Time Time Time Peak Peak speed speed * same bell-shaped regardless of direction & size of movement Similar hand motion profiles despite marked differences in the amplitude of movement. On average, healthy young adults spend 45-50% of movement time in the * Adapted from Morasso (1981) acceleration phase and 50-55% in the deceleration phase of movement. Aging and damage to the nervous system can increase movement time and the relative time spent in the deceleration phase. Kandel et al. (2016) Principles in Neural Science  Invariant features of upper limb movements Exemplar Subject Data Behavioural Task Acc. Dec. Acc. Dec. Acc. Dec. Time Time Time Time Time Time Peak Peak speed speed The targets require very different joint motion profiles. Flex. Ext. Adapted from Morasso (1981) Hand motion patterns remain relatively invariant despite markedly different joint motion patterns required to reach targets. This has led to the idea the nervous system explicitly selects, plans and controls desired hand trajectories. Kandel et al. (2016) Principles in Neural Science Control of the Movement Trajectory Control of the movement trajectory (1980-Present) Movement Select/Plan Execute Motor Movement Planning Parameters Motor Desired (select hand (e.g., desired Execution Joint Torques trajectory) joint angles) Muscle Activity pre-motor cortex Trajectory control considers movement planning and - execution as two separate processes. - M1 or primary motor cortex Serial processing framework implies the nervous system explicitly computes and attempts to reinforce specific hand trajectories when moving to a spatial goal. Flash T, Hogan N (1985) J Neurosci Hogan N (1984) J Neurosci · Bizzi E et al (1984) J Neurosci Understanding Movement Parameters distance more ~ higher velocity f(x) = ax + b The slope (term a in equation) is the rate of change in position (i.e., speed). slopes reveal differences in movement speed B Spatial Representation of Movement X position [cm] A A B A and B: same intercept (starting Time [ms] point), different speeds. Understanding Movement Parameters f(x) = ax + b The intercept (term b in equation) is the initial position (i.e., starting position). intercepts reveal differences in starting positions Spatial Representation of B X position [cm] Movement A A B A and B: different intercept (starting point), same movement Time [ms] speeds. Control of the Movement Trajectory Control of the movement trajectory (1980-Present) Movement Motor Movement Planning Parameters Motor Desired (select hand (e.g., desired Execution Joint Torques trajectory) joint angles) Muscle Activity Apparent importance of hand trajectories leads to following predictions: 1. Invariance of hand paths across movement amplitudes, directions, speeds, etc. 2. Sensorimotor system should attempt to reinforce planned hand trajectories when the limb is unexpectedly disturbed. Flash T, Hogan N (1985) J Neurosci Hogan N (1984) J Neurosci Bizzi E et al (1984) J Neurosci  Evidence the Trajectory Matters Movement Motor Motor Hand trajectory Desired Desired Planning Joint Angle Execution Joint Torques matters! Muscle Activity Behavioural Task Experimental Observations Start Unperturbed Arm pushed to target Flexion Target te Target Superimposed on perturbation trajectory TLat Hand returns to Extension nominal path due On some trials, apply an unexpected perturbation. to brief reversal Time of elbow in elbow motion Bizzi E et al J Neurosci 1984 in monkeys Hogan N J Neurosci 1984 perturbation Lecture Objectives 1. Understand the difference between gross and fine motor skills. 2. Understand the difference between closed and open motor skills. 3. Understand the difference between discrete, serial, and continuous motor skills. 4. Understand basic properties and processes involved in goal-directed arm movements. hand movement profile - steady - > speed & for 50 %, ↓ for 50 %. “Take home” message: Humans can perform a range of motor skills. These skills can be classified into different functional categories so we can study and understand them. Introduction to Motor Control and Learning Lecture 18 – Decision Making KNES 251 Introduction to Motor Control and Learning University of Calgary October 23, 2024 Fine and Gross Motor Skills Fine motor skills involve the use of small Gross motor skills are large muscles of the hands, fingers , toes, movements that require the use wrists, lips and tongue to perform small, of large muscles in the arms, precise movements. legs, torso and feet. They involve large movements They involve small movements with high (often involving the whole body). accuracy demands. Some examples Some examples include walking, include threading a needle, picking up a standing up from a seated position, coin, etc. reaching to open a door.  Continuum of Environmental Demands Closed Motor Skills Open Motor Skills Motor skills lie on a continuum between open and closed task and/or environmental demands.  Continuum of Task Demands Discrete Motor Skills Serial Motor Skills Continuous Motor Skills Invariant features of upper limb movements Legend Hand Speeds Target 30 cm 20 cm 10 cm 5 cm 2.5 cm Similar speed and acceleration profiles across movement Acceleration Profiles amplitudes. Start Start Stop Adapted from (Gordon et al., 1984) Similar scaling noted in hand acceleration profiles. Normalizing hand speeds in time and amplitude produces near identical profiles.  Invariant features of upper limb movements Exemplar Subject Data Behavioural Task Acc. Dec. Acc. Dec. Acc. Dec. Time Time Time Time Time Time Peak Peak speed speed Similar hand motion profiles despite marked differences in the amplitude of movement. On average, healthy young adults spend 45-50% of movement time in the Adapted from Morasso (1981) acceleration phase and 50-55% in the deceleration phase of movement. Aging and damage to the nervous system can increase movement time and the relative time spent in the deceleration phase. Kandel et al. (2016) Principles in Neural Science Life is full of choices Scenario 1 Scenario 2 Goal: Find and eat an apple We make some decisions faster than others…Why? Overview of Decisional Processes Processing Input Questions: Output What processing steps are involved in making a motor decision? What factors influence the speed of motor decisions? Lecture Objectives 1. Identify three stages of information processing 2. Understand factors that influence the speed of motor decisions 3. Describe how each stage influences motor decision- making. 4. Understand how anticipation can hasten the speed of motor decisions. Take Home Message: The speed that we select and initiate actions depends on the number of alternatives and the compatibility between the stimuli and response.  A (Simplified) Conceptual Model of Sensorimotor Decisions Conceptual model of the Input: Information we receive from sensorimotor system the environment through our senses – vision, audition, touch, proprioception. What happens in between? Output: Action response to a sensory input – reach, grasp, swing a baseball bat, catch a ball.  Expanding the Conceptual Model Involves detection and Input processing of sensory Conceptual model of the information including vision, sensorimotor system Stimulus audition, touch, Identification (Perception) proprioception, smell. Response Selection Selection of motor responses (Decision) given the goal of the task and nature of the environment. Response Programming basedon a (Action) goal-a o Action Output Preparing the motor system to generate the desired response.  Expanding the Conceptual Model Input Stimulus Identification (Perception) Response Reaction Time (RT): is the difference in Selection (Decision) time between stimulus presentation and the initiation of the motor response Response Programming (Action) Output Action Reaction Time (RT) is a measure of processing speed. now makewea decision fast one  Expanding the Conceptual Model Input Reaction Time (RT): is the time difference Stimulus Identification between stimulus presentation and the (Perception) initiation of a motor response. Response Selection (Decision) Movement Time (MT): time elapsed from end of reaction time to the completion of Response movement. Programming (Action) Response Time: Time elapsed between Output Action stimulus presentation and end of movement (RT + MT). where we get Sensory input till where we acheive goal  Factors that Affect the Speed of Motor Decisions 1. The # of response choices Simple vs. Choice Reaction Times (RT) Hick’s Law 2. Stimulus-Response (S-R) Compatibility 3. Anticipation  knownof time Simple Reaction Time alreadyahead Time interval between the presentation of a known stimulus and the motor response. On your mark…Set…GO!: The starter’s pistol is the stimulus that triggers the motor response (The response known/prepared in advance. Only uncertainty is time onset of stimulus…). Break Down and Analysis of Input a Simple Motor Decision Stimulus Identification (Perception) Response Selection (Decision) Response Programming (Action) On your mark…Set…GO! Output Action What factors play into a Simple RT decision?  What factors play into a Simple RT decision? Input Stimulus Identification (Perception) Stimulus identification: Detect starter’s pistol Response Selection Response Selection: Run (Decision) (known/prepared in advance) Response Response Programming: Launch Programming (Action) motor commands to move the limbs Output Simple RT is dominated by time Action required for stimulus identification (i.e., detect and process stimulus). The motor response is known and prepared in advance. Choice Reaction Time Time interval between the presentation of one of several possible stimuli and the beginning of one of several potential motor responses. Swerve or stop? Do nothing? Fastball or offspeed? What factors play into a Choice RT decision? Break down and analysis of a complex motor decision Stimulus identification: Detect deer’s position, speed. Oncoming traffic? Traffic behind you? Car’s speed? Weather and road conditions. Response Selection: Brake, swerve (left or right?), continue driving. Swerve or stop? Do nothing? Response Programming: Plan response and generate motor What factors play into a commands to move the Choice RT decision? limbs. Break down and analysis Input of a complex motor Stimulus decision Identification (Perception) Response Selection (Decision) Response Programming (Action) Swerve or stop? Do nothing? Output Action Requires time to detect and identify stimulus, then select, plan and initiate a response  matem or Summary dependent it Simple RT Task Choice RT Task is what spendena Input Input T spendalwhere Simple RT: time to Stimulus Stimulus Identification Identification detect stimulus and (Perception) (Perception) launch motor response dependent Response Response it of Selection Selection is (Decision) (Decision) what M Choice RT: time to Response Response Programming Programming detect and identify (Action) (Action) stimulus, then select, plan and initiate a Output Output Action Action motor response Simple vs. Choice RT – Let’s Give it a Try Simple RT Task Choice RT Task SimpleVsChoiceRT.pdf Potential Stimulus Stimuli Screen or Screen Keyboard Keyboard Orange Blue Button Stimulus Button Stimulus Button One stimulus, Several stimuli, several one response potential responses Prediction: Choice RTs are slower than simple RTs https://www.psytoolkit.org/lessons/experiment_simple_choice_rts.html  Factors that Affect the Speed of Motor Decisions 1. The # of response choices Simple vs. Choice Reaction Times (RT) Hick’s Law 2. Stimulus-Response (S-R) Compatibility 3. Anticipation Hick’s Law - The # of Choices Influences RT Hick discovered the relation between # of choices and RT could be described by a simple log-linear equation Hick’s Law: RT = a(log2(n)) + b where: n = # of S-R alternatives a = slope: the slope (term a in equation) is the expected increase in RT when the # of S-R alternatives is doubled b = y-intercept: the y-intercept ( the term b in equation) is the expected RT when no choice is required Interpreting Hick’s Law Simple Reaction Time Simple Reaction Time Choice Reaction Choice Reaction Time Times RT = a(log2(n)) + b No. of Choices (N)  Factors that Affect the Speed of Motor Decisions 1. The # of response choices Simple vs. Choice Reaction Times (RT) Hick’s Law 2. Stimulus-Response (S-R) Compatibility Types of S-R compatibility 3. Anticipation  Spatial Compatibility Examples Example A: Spatially Compatible Which burner does each dial control? Which design would lead to faster RT? Example B: Spatially Incompatible Example A is easier to use due to spatial mapping between burners and control dials. S-R Compatibility: Simon Task Instructions: 1. Fixate central cross. 2. Respond to ‘left’ with left key press, ‘right’ with right key press. https://www.psytoolkit.org/lessons/experiment_compatibility.html Simon Task – Let’s give it a try SimonTask_Trials.png Hypothesis: people respond more slowly in spatially- incompatible trials. https://www.psytoolkit.org/lessons/experiment_compatibility.html  Other Types of Compatibility Movement Compatibility: The movement of displays and controls relative to the response of the system being displayed or controlled. The turn signals in a car align with the rotation of the steering wheel – CCW for left and CW for right Window controls in a car often align with the location and motion of the window (similarly for side mirrors)  Factors that Affect the Speed of Motor Decisions 1. The # of response choices Hick’s Law Simple vs. Choice Reaction Times (RT) 2. Stimulus-Response (S-R) Compatibility Types of S-R compatibility 3. Anticipation Types of anticipation ↳ Anticipation Spatial Anticipation Temporal Anticipation Spatial-Temporal Anticipation Benefit: Interception Cost: Player evades D-Back and scores TD Lecture Objectives 1. Identify three stages of information processing 2. Understand factors that influence the speed of motor decisions 3. Describe how each stage influences motor decision- making. 4. Understand how anticipation can hasten the speed of motor decisions. Take Home Message: The speed that we select and initiate actions depends on the number of alternatives and the compatibility between the stimuli and response. Tradeoff between the Speed and Accuracy of Voluntary Motor Actions KNES 251 Introduction to Motor Control and Learning University of Calgary October 25, 2024 Overview of Decisional Processes Processing Input Questions: Output What processing steps are involved in making a motor decision? What factors influence the speed of motor decisions?  Expanding the Conceptual Model Input is where itis Stimulation Conceptual model of what Stimulus Identification: What the motor system Stimulus Identification information is available and is (Perception) most relevant? decision making phase Response Response Selection: What Selection (Decision) options are available? #o send motor command to periphary move Response Response Programming: muscles Programming (Action) Planning and generating the chosen response Output = unknown Action box black Simple and Choice Reaction Times Simple Reaction Time Choice Reaction Time Time interval between the Time interval between the presentation of one known presentation of one of several stimulus and the motor possible (unanticipated) stimuli response. and the beginning of one of several motor responses. Summary Simple RT Task Choice RT Task (Typically fast RTs) (Slower RTs) Input ** Input Simple RT: time to Stimulus Stimulus Identification Identification detect stimulus and (Perception) (Perception) launch motor response Response Response Selection Selection (Decision) (Decision) Choice RT: time to Response Response Programming Programming detect and identify (Action) (Action) stimulus, then select, plan and initiate a Output Output Action Action motor response  choices ↑ time it takes to make & = a decision Brief Introduction to Hick’s Law Simple Reaction Time Simple Reaction Time Choice Reaction Choice Reaction Time Times RT = a(log2(n)) + b given No. of Choices (N)  Compatibility Examples Spatial Compatibility Example A: Spatially Compatible Movement Compatibility Example B: Spatially Incompatible The turn signals in a car align with the rotation of the steering wheel – CCW for left and CW for right  harder to conceptual in sports Anticipation Spatial Anticipation Temporal Anticipation > - get time to plan out when time will come inval Spatial-Temporal this ( Anticipation or moral jus I  Everyday Examples of Speed-Accuracy Tradeoffs High Speed - Low Accuracy Low Speed - High Accuracy We often make movements with varying accuracy demands.  Everyday Examples of Speed-Accuracy Tradeoffs High Speed - Low Accuracy Low Speed - High Accuracy In general, we can move quickly at the cost of accuracy or accurately at the cost of speed.  Everyday Examples of Speed-Accuracy Tradeoffs High Speed - Low Accuracy Low Speed - High Accuracy It’s difficult to do both…Why? Lecture Objectives 1. Identify factors that influence movement accuracy. 2. Describe Fitts’ Theorem and identify practical examples of the speed-accuracy tradeoff from sports and daily life. 3. Identify physiological factors that contribute to the tradeoff between the speed and accuracy of movement. “Take home” message: The motor system is often faced with conflicting goals and has to achieve some type of balance.  Factors that Affect the Spatial and Temporal Accuracy of Voluntary Actions Factors that Influence the Spatial Accuracy of Movement Motor Variability Scales with Movement Speed Fitts’ Theorem Neurophysiological Principles Governing Movement Variability Accuracy of Aiming Movements Decreases with Speed Behavioural Task Overview of Task: Participants made rapid, goal- oriented aiming movements while holding a stylus. Movements were time constrained: 140, 170, or 200 ms. 3 2 1 Movement time calculated as time between when hand speed first crossed threshold (5% peak speed) to Participants made rapid, goal- when it fell below the threshold. directed aiming movements from 1 Movements had to be completed of 3 starting positions to a spatial within 10% of time constraint to be considered successful and retained target while holding a stylus. for analysis. This simple task can provide information about the relationship between the speed and variability of human movement.  error increases as speed increases Accuracy of Aiming Movements Decreases with Speed Behavioural Task Dispersion of Endpoints Increases with Movement Speed Intermediate Target (Target 2) 3 2 1 Near Target (Target 1) Far Target (Target 3) Participants made rapid, goal- directed aiming movements from 1 of 3 starting positions to a spatial Increased Variability Increased target while holding a stylus. Speed Near Target: Best accuracy, slowest average movement speed. Intermediate Target: Intermediate accuracy, intermediate movement speed. Far Target: Lowest accuracy, fastest average speed.  movement times are constrained , dispersion speed when of movement endpoints is directly proportional to movement Accuracy of Aiming Movements Decreases with Speed Behavioural Task Dispersion of Endpoints Increases with Movement Speed Intermediate Target (Target 2) 3 2 1 Near Target (Target 1) p Far Target (Target 3) Participants made rapid, goal- directed aiming movements from 1 of 3 starting positions to a spatial Increased Variability Increased target while holding a stylus. Speed What happens When if we times movement let people self-select the are constrained, thedispersion speed of their of movement endpoints movements (but tellis them directly toproportional to movement move as quickly speed. as possible)?  Factors that Affect the Spatial and Temporal Accuracy of Voluntary Actions Factors that Influence the Spatial Accuracy of Movement Motor Variability Scales with Movement Speed Fitts’ Theorem Neurophysiological Principles Governing the Variability of Movement  Fitts’ Theorem – Movement Amplitude and Accuracy Demand Impact Movement Time (MT) Fitts (1954) discovered the relation between movement amplitude, accuracy, and MT could be described by a log-linear equation Fitts’ Theorem: MT = a[log2(2A/W)] + b amplitude movement time where: width movemen as t target a = slope M ↑ time ↓ A = movement amplitude weovement as W = target width (i.e., accuracy demand) b = y-intercept Index of difficulty (ID) = [log2(2A/W)] it makes & MA > - harder (a) it makes Ath Cal harder The Index of Movement Difficulty Influences MT Speed-Accuracy Tradeoff: Tendency to ‘give-up’ movement speed for accuracy. Low speed, high index of difficulty W A MT = a[log2(2A/W)] + b High speed, low index of difficulty  Brief Introduction to Fitts’ Theorem Speed-Accuracy Tradeoff: Tendency to ‘give-up’ Low Index of Difficulty movement speed for accuracy. Low index of difficulty MT (s) High Index of Difficulty High index of difficulty MT = a[log2(2A/W)] + b ID (bits)  Understanding Fitts’ Theorem MT = a[Log2(2A/W)] + b Movement time (MT) increases as movement amplitude (A) increases. if we MT is constant for a Low index of MA& TW it stays constant fixed ratio of difficulty movement amplitude MT (s) (A) to target width (W). High index of MT increases as the difficulty target width (W) decreases (i.e., accuracy demand increases) or amplitude of movement ID (bits) increases. Speed-Accuracy Tradeoffs Across the Lifespan Young Adults 1.4 Older Adults Differences 1.2 at low ID Different 1.0 slopes How do we expect Speed- MT (s) me 0.8 ma Accuracy Tradeoffs to differ Young Adults between as young and older 0.6 adults? Older Adults > - cognitive issues , 0.4 Increased difficulty ↓ sensory Feedback : or Slower less accurate 2 3 4 5 6 adults than young Index of Difficulty (ID) less accurate into abt ↓GTO loose skin ↑ forces they're producing blc of ↓ collagen ↓ collagen = = Adapted from Ketcham, Seidler et al (2002) J Gerontol  Speed-Accuracy Tradeoffs Across the Lifespanhave as tasks get harder , older adults time in their reaction ↑ change Young Adults 1.4 Older Adults Older Adults Differences 1.2 at low ID Different 1.0 slopes MT (s) Higher intercept for older 0.8 Young Adults adults means baseline movements (unconstrained) 0.6 are slower than young adults. 0.4 Increased difficulty Higher slope for older adults 2 3 4 5 6 means speed-accuracy tradeoff is more severe than Index of Difficulty (ID) young adults. Adapted from Ketcham, Seidler et al (2002) J Gerontol  Speed-Accuracy Tradeoffs Across the Lifespan Young Adults Hand Motion Profiles End Target Movement Movement initiation initiation Start Position Hand Velocity Profiles Peak Velocity Peak Velocity Smoother More Movements corrections Faster Older Adults Movements Young adults make smoother, faster movements with fewer corrections than older adults. spend a time in deccelaration pra Adapted from Ketcham, Seidler et al (2002) J Gerontol  a likely to use them if things r easy to use you're Examples of Fitts’ Theorem in Daily Life Webpage Design Keyboard Design Infrequently used areas (keys) are Frequently used areas (keys) are smaller to increase accuracy demand larger to reduce accuracy demand at the expense of time cost. This also and save time minimizes risk of error.  Examples of Fitts’ Theorem – Golf Clubs Impose a Speed-Accuracy Tradeoff Driver Pitching Wedge Driver is longer, increasing (swing) Wedge is shorter, decreasing (swing) ball speed but reducing accuracy. ball speed but increasing accuracy. How do we Measure Speed-Accuracy Tradeoffs in the lab? fig06_01.jpg Instructions: Make alternating movements between targets as quickly and accurately as possible. Hypothesis: MTs will increase with increased amplitude or accuracy demands (Try Expts. 3 & 5).  Factors that Affect the Spatial and Temporal Accuracy of Voluntary Actions Factors that Influence the Spatial Accuracy of Movement Motor Variability Scales with Movement Speed Fitts’ Theorem Neurophysiological Principles Governing the Amplitude of Movement Error Activation of skeletal muscles for voluntary movement. as a force Motor Variability is Proportional to the of aut we also Amount of Force Produced · Motor variability scales with force production 0.6 80% Trendline for Standard Deviation of MVC Most Variable young adults Force (% MVC) 60% MVC 0.4 0.2 ~Linear scaling 20% across range of MVC forces produced 0 Least Variable 10 20 30 40 50 Force (% MVC) Subject is asked to generate a fixed level of Scaling of force variability is force. As force level increases, the subject proportional to the amount of force shows more variability in maintaining a produced. constant force level. Hamilton and Wolpert (2002) J Neurophysiol.  Motor Variability is Proportional to the Amount of Force Produced Force variability increases with force produced. 80% MVC Most Variable 60% Peak in force MVC variability at 75% MVC. & 20% MVC Force variability peaks at 75% Least Variable maximal voluntary contraction (MVC) and Subject is asked to generate a fixed level of decreases slightly until 100% force. As force level increases, the subject MVC. shows more variability in maintaining a constant force level. Hamilton and Wolpert (2002) J Neurophysiol.  faster = ↑ force = fast glycolytic = & Mr more faster a fused tetanus ↓ - variability. Relationship between Force Variability and Motor Behaviour Slight decrease in variability for very fast Force variability movements that approach MVC. increases with force produced. Peak in force variability at 70% Faster MVC. movements are more variable (more force required) Increase in MVC Force variability peaks at 75% maximal voluntary contraction (MVC) and decreases slightly Increased MT until 100% MVC. Behaviour shows a similar decrease in variability near maximal exertion. Hamilton and Wolpert (2002) J Neurophysiol.  Variability of Contraction Depends on the Properties of Motor Unit Recruitment Motor Unit: Consists of a motor neuron and all of the muscle fibers it innervates. Innervation Number: The number of muscle fibers innervated by a single motor neuron. Slow twitch (fatigue resistant) have smaller innervation numbers than fast twitch (fast fatiguing) muscle fibers. Fast twitch muscle fibers tend to contribute to larger motor units than slow twitch muscle Size-recruitment principle says that small fibers. motor units are recruited first. The recruitment of large motor units correlates with the variability of muscle force production.  Variability of Contraction Depends on the Properties of Motor Unit Recruitment The twitch potential of a single fast twitch fiber can be 20x larger than a typical slow twitch fiber. Thus, activating larger fibers can increase the variability of force production during voluntary actions. Kandel et al. (2014) Principles of Neural Science Lecture Objectives 1. Identify factors that influence movement accuracy. 2. Describe Fitts’ Theorem and identify practical examples of the speed-accuracy tradeoff from sports and daily life. 3. Identify physiological factors that contribute to the tradeoff between the speed and accuracy of movement. “Take home” message: The motor system is often faced with conflicting goals and has to achieve some type of balance. Attention and Performance Limitations on Performance KNES 251 Introduction to Motor Control and Learning University of Calgary October 28, 2024  Everyday Examples of Speed-Accuracy Tradeoffs High Speed - Low Accuracy Low Speed - High Accuracy We can be fast at the cost of accuracy or vise versa. It’s difficult to do both…Why?  Accuracy of Aiming Movements Decreases with Speed amplitude is size of south Behavioural Task Dispersion of Endpoints Increases with Movement Speed Intermediate Target (Target 2) 3 2 1 Near Target (Target 1) Far Target Participants made rapid, goal- (Target 3) directed aiming movements from 1 of 3 starting positions to a spatial Increased Variability Increased target while holding a stylus. Speed How far we have to more & 1. width (size 2 of target) affect speed When movement times are constrained, the dispersion of movement endpoints is directly proportional to movement speed. if we reach faster we have a variability , changing length var. &) error What happens if we let people self-select the speed of their movements? Fitts Theorem in Voluntary Motor Actions Low speed, high index of difficulty W A MT = a[log2(2A/W)] + b High speed, low index of difficulty  Understanding Fitts’ Theorem Speed-Accuracy Tradeoff: Tendency to ‘give-up’ movement Movement time (MT) speed for accuracy. increases as movement amplitude (A) increases. MT = a[Log2(2A/W)] + b as target lifted Low index of MT is constant for a difficulty fixed ratio of movement MT (s) amplitude (A) to target width (W). High index of difficulty MT increases as the target width (W) decreases (i.e., accuracy demand increases) or amplitude of movement increases. ID (bits)  Speed-Accuracy Tradeoffs Across the Lifespan Young Adults 1.4 Older Adults Older Adults Differences 1.2 at low ID Different 1.0 slopes MT (s) Higher intercept for older 0.8 Young Adults adults means baseline movements (unconstrained) 0.6 are slower than young adults. 0.4 Increased difficulty Higher slope for older adults 2 3 4 5 6 means speed-accuracy tradeoff is more severe than Index of Difficulty (ID) young adults. Adapted from Ketcham, Seidler et al (2002) J Gerontol Speed-Accuracy Tradeoffs Across the Lifespan Young Adults Hand Motion Profiles End Target Movement Movement initiation initiation Start Position Hand Velocity Profiles Peak Velocity Peak Velocity Smoother More Movements corrections Faster Older Adults Movements Young adults make smoother, faster movements with fewer corrections than older adults. Adapted from Ketcham, Seidler et al (2002) J Gerontol at $75 1. most mu % Motor Variability is Proportional to the recruited name Amount of Force Produced ·w - Motor variability scales 80% · 0.6 with force production Trendline for Standard Deviation of MVC Most Variable young adults Force (% MVC) 60% MVC 0.4 0.2 ~Linear scaling 20% across range of MVC forces produced 0 Least Variable 10 20 30 40 50 Force (% MVC) Subject is asked to generate a fixed level of Scaling of force variability is force. As force level increases, the subject proportional to the amount of force shows more variability in maintaining a produced. constant force level. Hamilton and Wolpert (2002) J Neurophysiol.  Variability of Contraction Depends on the Properties of Motor Unit Recruitment The twitch potential of a single fast twitch fiber can be 20x larger than a typical slow twitch fiber. Thus, activating larger fibers can increase the variability of force production during voluntary actions. Kandel et al. (2014) Principles of Neural Science  Examples of Fitts’ Theorem in Daily Life Webpage Design Keyboard Design Infrequently used areas (keys) are Frequently used areas (keys) are smaller to increase accuracy demand larger to reduce accuracy demand at the expense of time cost. This also and save time minimizes risk of error. Why do athletes ‘choke’ under pressure? Screen Shot 2015-07-26 at 3.46.00 PM.png Sergio Garcia loses lead on 17 th hole of Round 4 at 2013 Players Invitational Lecture Objectives 1. Understand properties of attention. 2. Identify how attention may limit information processing. 3. Describe how attention impacts motor decisions. 4. Describe how attention influences the capability to perform voluntary motor actions. “Take home” message: Many factors influence how arousal and attention impact motor ampitadeNoa performance What is Attention? Attention is a limited cognitive resource or pool or resources that is available and can be used for different tasks or purposes. When the attentional demands of a task are low, performing a secondary task may not detract from performance. Example: Washing plates and talking on the phone. What is Attention? Attention is a limited cognitive resource or pool or resources that is available and can be used for different tasks or purposes. When the attentional demands of a task are high, performance of a secondary task likely has a negative impact on both tasks. Examples: 1. Texting and driving. 2. Chopping vegetables and holding a conversation. What is Attention? Low Attentional Demand High Attentional Demand Revisit information processing model to understand how attention impacts motor performance.  Three Stages of Information Processing Input Conceptual model of Stimulus Identification: What the motor system Stimulus Identification information is available and is (Perception) most relevant? Response Response Selection: What Selection (Decision) options are available? Response Response Programming: Programming (Action) Planning and generating the chosen response Output Action How Attention Influences Motor Performance Input 1. Stimulus Identification Stimulus 2. Response Selection Identification (Perception) 3. Response Programming Response Selection 4. Choking Under Pressure (Decision) Response Programming (Action) Output Action  How Attention Influences Motor Performance Input 1. Stimulus Identification Parallel Processing of Sensory Information Stimulus Identification (Perception) 2. Response Selection 3. Response Programming Response Selection (Decision) 4. Choking Under Pressure Response Programming (Action) Output Action Parallel Processing of Sensory Information The ability to process two streams of sensory information simultaneously. Conceptual Model Input Stimulus Identification (Perception) Auditory Cue Visual Cue Response Selection (Decision) Environmental Information Response Programming (Action) Output Different streams of sensory Action information can be often be processed simultaneously and independently. Parallel Processing of Sensory Information The ability to process two streams of sensory information simultaneously. Conceptual Model Input Stimulus Identification (Perception) Auditory Cue Visual Cue Response Selection (Decision) Environmental Information Response Programming (Action) Output Is this always true or are there some Action limitations in how well the nervous system can process sensory information in parallel?  Limitations in Parallel Processing: The Stroop Effect Yell out the COLOUR OF THE TEXT as fast as you can. YELLOW GREEN BLUE RED Why is it easier to say the colour when the word and colour match?  Challenges in parallel processing Input See the colour RED Stimulus Identification (Perception) Response Selection (Decision) Response Programming (Action) See the colour = Read the word Output Action Read the No interference in word stimulus identification and response selection  Challenges in parallel processing Input See the colour RED Stimulus Identification (Perception) Response Selection (Decision) See the Read Response Programming (Action) colour ≠ the word Output Action Read the Interference or competition word in stimulus identification and response selection!  How Attention Influences Motor Performance Input 1. Stimulus Identification Parallel Processing of Sensory Information Stimulus Identification (Perception) 2. Response Selection Controlled vs. Automatic Processing Response Selection 3. Response Programming (Decision) 4. Choking Under Pressure Response Programming (Action) Output Action  The Control vs. Automatic Continuum Controlled Automatic Processing Processing PRACTICE → ← PRESSURE Slow Fast Just essive Deliberate Smooth Consciously aware Unconscious performance High attention demand Low attention demand “Novices” “Experts”  The Control vs. Automatic Continuum Controlled Automatic Processing Processing PRACTICE → ← PRESSURE Practice can help automatize motor skills performance and free attentional resources for motor decisions. Pressure can reduce the availability of attentional resources for motor decisions and lead to controlled processing.  How Attention Influences Motor Performance Input 1. Stimulus Identification Parallel Processing of Sensory Information Stimulus Identification (Perception) 2. Response Selection Controlled vs. Automatic Processing Response Selection 3. Response Programming (Decision) Spatially and temporally-incompatible movement. Response Programming (Action) 4. Choking Under Pressure Output Action  How Attention Influences Motor Performance Input 1. Stimulus Identification Parallel Processing of Sensory Information Stimulus Identification (Perception) 2. Response Selection Controlled vs. Automatic Processing Response Selection 3. Response Programming (Decision) Spatially and temporally-incompatible movement. Response Programming (Action) 4. Choking Under Pressure Output Action Spatially and Temporally-Incompatible Movements Drumming requires the limbs to perform independent actions while maintaining different rhythms.  Example of Temporally and Spatially- acompeten are a Incompatible Movements This task is difficult because the two arms must perform independent actions. This causes movement interference.  How Attention Influences Motor Performance Input 1. Stimulus Identification Parallel Processing of Sensory Information Stimulus Identification Inattention Blindness (Perception) 2. Response Selection Response Controlled vs. Automatic Processing Selection (Decision) 3. Response Programming Spatially and temporally-incompatible Response Programming movement. (Action) 4. Choking Under Pressure Action Output Why does choking seem more common in golf? Rory McIlory collapse at 2011 Masters Tiger Woods meltdown at 2012 Open Phil Mickelson implodes at 2006 U.S. Open Greg Norman blows up at 1996 Masters Why does choking seem more common in golf? required reward (1) a lot of pressure complex task , a precision , , , Pul watching Screen Shot 2015-07-26 at 3.46.00 PM.png Is there a link between ‘choking’, the level of arousal and/or the pressure of competition?  arousal become low can depending Definition of Arousal situations takoua Arousal refers to the level of excitement produced under stress. Low Arousal High Arousal Arousal is a key determinant of performance in tasks where the speed or accuracy of motor decisions is important.  How does arousal impact performance? Inverted U Principle: The relationship between arousal level and performance There is an entire subfield of sports psychology that is dedicated to how athletes handle pressure and arousal in competition, and whether they can learn to change it with practice. Some athletes perform better under pressure ‘Choked’ Under Pressure Rallied Under Pressure Adam Scott collapsed on last 4 holes Ernie Els rallied on last 4 holes and and lost the 2012 Open Championship. won the 2012 Open Championship. What’s the difference between athletes that thrive or break under pressure?  How an individual’s arousal can affect their performance Ernie Els Adam Scott Individual Zone Optimal Functioning (IZOF): The range of arousal levels associated with a person’s maximum performance Performance Anxiety Relationship between arousal and performance depends on the athlete. Some Tasks Require More Arousal Than Others High Medium Low Complexity Complexity Complexity Low Arousal Medium Arousal High Arousal When arousal is low, performance is better in complex cognitive tasks with high precision demands. Lecture Objectives 1. Understand properties of attention. 2. Identify how attention may limit information processing. 3. Describe how attention impacts motor decisions 4. Describe how attention influences the capability to perform voluntary motor actions. “Take home” message: Many factors influence how arousal and attention impact motor performance  Muscle Spindle Receptors and Basic Stretch Reflexes Lecture 21 – Receptors and Spinal Control of Somatosensory Feedback KNES 251 Introduction to Motor Control and Learning University of Calgary October 30, 2024 What is Attention? Low Attentional Demand High Attentional Demand Revisit information processing model to understand how attention impacts motor performance.  Three Stages of Information Processing Input Conceptual model of Stimulus Identification: What the motor system Stimulus Identification information is available and is (Perception) most relevant? Response Response Selection: What Selection (Decision) options are available? Response Response Programming: Programming (Action) Planning and generating the chosen response Output Action Stimulus Identification – Parallel Processing of Sensory Information The ability to process two streams of sensory information simultaneously. Conceptual Model Input Stimulus Identification (Perception) Auditory Cue Visual Cue Response Selection (Decision) Environmental Information Response Programming (Action) Output Is this always true or are there some Action limitations in how well the nervous system can process sensory information in parallel?  Stimulus Identification – Challenges in parallel processing Input Input See the colour See the colour Stimulus Stimulus RED RED Identification Identification (Perception