Intratask Developmental Sequences: Theory and Application

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Intra-task Developmental Sequences Theory and
Application

• This learning module was created by
• Stephen Langendorfer, Ph.D.,
• Mary Ann Roberton, Ph.D.
• Biomechanics/Motor Behavior Laboratory
• School of Human Movement, Sport, Leisure
• Studies
• Bowling Green State University
• Bowling Green, OH 43403

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Developmental Sequences

• are of two types -
• inter-task or between-task sequences
• intra-task or within-task sequences

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Inter-task Development Sequences

• ....a series of tasks that have been ordered
  according to the age at which most persons
  achieve some criterion level of each task.
• The best known is Mary Shirleys infant sequence
  for the acquisition of independent walking
• Another name for the infant sequence is the
  motor milestones of infancy

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Inter-task Development Sequences

• Another example is the developmental sequence for
  foot locomotion.
• For further information on the foot locomotion
  developmental sequence, click the underlined
  words.
• The rest of this module will deal with intra-task
  developmental sequences.

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Intra-task Developmental Sequences Key Points

• Intra-task developmental sequences are markers of
  qualitative change in human movement.
• They are tracked over the lifespan (ideally) or
  some portion of the lifespan (e.g., childhood).
• Each qualitative description within an intra-task
  sequence is known as a level or step.
• The occurrence of each level within the sequence
  is age-related but not age-determined.

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Key Points (cont.)

• The chance that developmental sequences will
  occur at any particular point in the lifespan is
  just that a chance
• Developmental sequences are probabilistic, that
  is, they are based on chance or probabilities.

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Key Points (cont.)

• Developmental sequences are interesting
  theoretically because they seem to result from
  interactions within a dynamic system composed of
• the person, the task that person is trying to do,
  and the environment within which they are trying
  to move.

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Key Points (cont.)

• Developmental sequences are also interesting from
  a practical perspective because they are
  observable markers of change. Click here for more
  on change
• either progressive change, as perhaps from the
  result of instruction, increased fitness, or
  recovery from injury
• or regressive change, perhaps from illness,
  injury, or aging.

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Change Words

• on the developmental continuum
• Progression forward change
• Regression backward change
• These are not judgmental words they are simply
  descriptive based upon developmental observation
  and study.
• Return

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Key Points (cont.)

• As markers of change, developmental sequences can
  be used as assessment tools by clinicians (e.g.,
  teachers, caregivers, coaches, therapists).

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Intra-task Developmental Sequences

• The following slides will discuss each of these
  key points in greater detail. You will also want
  to refer to the references at the end of the
  module for further information.

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Intra-task Developmental Sequences. . .

• . . . are markers of qualitative change in human
  movement.
• each level of a developmental sequence describes
  a way of moving that is noticeably different from
  preceding or subsequent levels. This difference
  is not more of what has occurred instead it is
  something new.

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An Example of Something New

• In striking a ball,
• flexing the bodys trunk forward at the hips is
  one way of moving the trunk to develop striking
  force.
• Rotating the trunk is another way to develop
  force.
• These two ways are qualitatively different.
  Flexing more and more will never become rotation.

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Something New (cont.)

• In striking a ball
• the person who shows trunk flexion at one point
  in time and then trunk rotation at another point
  in time.
• has developed something new in her/ his
  repertoire of striking behaviors.

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A Developmental Sequence

• is an ordering of the qualitative changes that
  occur as people perform a motor task
• over their entire lifespan or some part of the
  lifespan.
• the changes are ordered chronologically,
• which makes developmental sequences age-related
  (but they are not age-determined)

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Developmental Curves

• Developmental sequences are often plotted in
  graphs that depict the lifespan or parts of it.
• Usually each level of the sequence is plotted as
  a separate curve.
• The curve represents the percentage of persons at
  a given age who display the behavior represented
  by that level or step.

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Developmental Curves
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How to Read Developmental Curves

• In the preceding graph about 95 of the two year
  olds were displaying the behavior represented by
  level one.
• About 5 were displaying the behavior represented
  by level two. No one was displaying level three
  behavior.
• Can you read the graph to determine what
  percentage of the 20 year olds were displaying
  each of the three levels?

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How to Read Developmental Curves

• Notice that the horizontal axis is a measure of
  time passing (usually age).
• Notice that the vertical axis is the percentage
  of persons showing the behavior at a given age.
• If a developmental sequence is ordered correctly,
  the curves will
• rise and fall in consecutive order, with each
  curve becoming modal after the level before it
  and prior to the level following it.

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Developmental Curves

• When graphed this way, developmental sequences
  nicely show the
• coming-to-be and the passing-away
• that is the hallmark of motor development.

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Developmental Sequences are Probabilistic

• Earlier we said that developmental sequences were
  age-related, not age-determined.
• That is, at each age certain percentages are
  associated with the likelihood of a person
  displaying the behavior represented by each
  developmental level. Since each level has a
  possibility of occurring, age does not determine
  which level a person will display.

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Developmental Sequences are Probabilistic

• When they are based on a sufficient number of
  people, the percentages at each age give an
  estimate of the probability associated with the
  appearance of a particular developmental level
  at that age.

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Probabilities

• Look again at the graph on the right
• State the probability of drawing from a group of
  20 year olds a 20 year old who shows level two
  behavior.

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Probabilities

• Do you see how the percentages collected on
  previous samples become your educated best
  guess as to the distribution of developmental
  levels in another sample?
• Also, this example shows how no one can know
  ahead of time what the movement of a person of a
  particular age will look like.
• We can only state the probabilities associated
  with each level of the developmental sequence for
  that age.

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Constraints The Theory Behind Developmental
Sequences

• Karl Newell, a researcher at Penn State
  University, presented a way to think about the
  interactions of person, task, and environment.

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Constraints Theory Newells (1986) Triangle

• The triangle represents the dynamic system which
  leads to the emergence of a particular movement
  at a particular time.
• That emergent movement is called a developmental
  level.

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Constraints Theory Newells (1986) Triangle

• Each corner of the triangle represents an element
  of the system, e.g.,
• P the person
• T the task
• E the environment

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Constraints TheoryThe Newell Triangle (cont.)

• The person has particular characteristics that
  he/she brings to the task e.g., body size,
  neural development, information processing
  capabilities.

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Constraints TheoryThe Newell Triangle (cont.)

• The task has particular characteristics, usually
  called task demands e.g., ball size, target
  size, distance to throw or run.
• The environment is the ambience surrounding the
  person-task e.g., air, water, noise, observers,
  culture.

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Constraints TheoryThe Newell Triangle (cont.)

• The sides of the triangle demonstrate the
  relationships within the system. These
  relationships are called constraints.
• Person-task and person-task-environment are key
  constraints.

P
Constraints
E
T
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How the P-T-E Dynamic System Works

• Person-Task Constraint
• Picture a small child attempting to reach a
  cupboard at a certain height in order to open it.
• Picture a tall adult attempting to reach the same
  cupboard of the same height in order to open it.
• The reaching and opening movements would be
  different.

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Their movements would differ....

• because their relationship to the task would be
  different.
• In this example, the task stayed the same, but
  the size of the persons changed. This change, in
  turn, changed the relationship between the person
  and the task....side P-T of the Newell triangle.

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Systems Theory

• For more information on systems and how they
  work, click on the underlined words.

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Markers of Change The Practical Use of
Developmental Sequences

• Developmental sequences are observable markers of
  change. They are easy to see.
• This makes them useful from a practical
  perspective.

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Observable Markers of Change

• Teachers, therapists, parents, and others
  interested in changing movement can use
  developmental sequences as observation tools that
  can be used to chart progress.

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Markers of Change The Practical Use of
Developmental Sequences

• For more information on the importance of
  movement observation skills for clinicians, click
  the underlined words.
• For more information on the use of developmental
  sequences as assessment tools, click the
  underlined words.

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References

• Newell, K. (1986). Constraints on the development
  of coordination. In M.G. Wade H.T.A. Whiting
  (Eds.), Motor development in children Aspects of
  coordination and control (341-360). Dordrecht
  Martinus Nijhoff.
• Roberton, M.A., Halverson, L.E. (1984).
  Developing children - Their changing movement.
  Available first author.
• Roberton, M.A., Langendorfer, S. (1980).
  Testing motor development sequences across 9-14
  years. In C. Nadeau et al. (Ed.), Psychology of
  motor behavior and sport - 1979 (269-279).
  Champaign, IL Human Kinetics.
• Roberton, M.A., Williams, K., Langendorfer, S.
  (1980). Pre-longitudinal screening of
  developmental sequences. Research Quarterly for
  Exercise and Sport, 51, 724-731.