Intra-task Developmental Sequences: Theory and

ApplicationThis learning module was created by

Stephen Langendorfer, Ph.D., & Mary Ann Roberton, Ph.D.

Biomechanics/Motor Behavior LaboratorySchool of Human Movement, Sport, & Leisure

StudiesBowling Green State University

Bowling Green, OH 43403

Developmental Sequences

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

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 Shirley’s infant sequence for the acquisition of independent walking– Another name for the infant sequence is the

“motor milestones” of infancy

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.

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.

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.

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.

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.

Key Points (cont.)

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

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.

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.

An Example of “Something New”

• In striking a ball, – flexing the body’s 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.

“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.

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)

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.”

Developmental Curves

0

10

20

30

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50

60

70

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2 8 12 20 30

% o

f o

ccu

rren

ce

Level One

Level Two

LevelThree

Age in Yrs.

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?

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.

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.

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.

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.

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. 0

10

20

30

40

50

60

70

80

90

100

2 8 12 20 30

% of

occu

rrenc

e

Level One

Level Two

LevelThree

Age in Yrs.Age in Yrs.Age in Yrs.

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.

Constraints: The Theory Behind Developmental

SequencesKarl Newell, a researcher at Penn State University,

presented a way to think about the interactions of person, task, and environment.

Person

Environment Task

Developmental Level

Constraints Theory: Newell’s (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.

Constraints Theory: Newell’s (1986) Triangle

Each corner of the triangle represents an element of the system, e.g.,P = the person

T = the task

E = the environment

P

E T

Constraints Theory:The Newell Triangle (cont.)

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

Constraints Theory:The 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.

Constraints Theory:The Newell Triangle (cont.)

• The sides of the triangle demonstrate the relationships within the system. These relationships are called constraintsconstraints.

• Person-task and person-task-environment are key constraints.

P

E T

Constraints

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.

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.

Systems Theory

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

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.

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.

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.

ReferencesNewell, 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.