PSYC306 - Motor Development, Action Perception & Action Production

Classic view:
An adaptive change towars movement competence throughout the lifespan (Gallahue, 1986)
-ve, does not capture all aspects of motor development

A product, end state (descriptive theory)

A process, continuation (explanatory theory)

• Descriptive theory
• Ranks developmental milestones sequentially
• Assumes mean age for each milestone
  • used to identify when deficits may be apparent in development
• Focuses on maturation, the unfolding of natural development (Ulrich, 1999)

Problems of Folk Psychology's explanation

-ve, how does this explain how impairments may occur?
-ve, what causes this natural change in development?
-ve, how do you explain/account for the discontinuation or depletion of old skills when new ones emerge? e.g. crawling to walking

Explanations of functional progression of motor skills:

Cephalo-Caudal: Head to tail
The theory that infants acquire motor skills relevant to the head first, progressing the the legs.

Proximal-Distral: Central to peripheral
The theory that infants acquire motor skills relevant to central parts of the body first, and extremities last e.g. arms then fingers.

Computational robots programmed with these explanations for motor development find it extremely difficult to acquire motor skills in the same way as human infants, due to the innumerate number of degrees of freedom associated with finite movement.

• Key Acquiring a new skill is fundamental to skilled performance
• A landmark in motor development

Key milestones: postural, reaching, grasping, locomotion

• The months for which a child should reach a certain milestones are often listed sequentially according to folk psychologys view of motor development. However the variance as charted by standard deviation for the acquisition of each behaviour by infants, is large. Thus highlighting the huge variation in the acquisition or development of motor skills across individuals, suggesting that acquisition time is not universal.

Classic theory: maturation
A biological development or change enables the development of behavioural and cognitive

• Evidence: there is similar development progression cross-culturally

Interaction between biological change and the environment
Opportunities to practice may be cause for why milestones may be hit earlier in some children compared to others, as they have had ample opportunity to practice within the environment the skills biologically given.

• Evidence: some cultures acquire motor behaviours significantly sooner than others
• Examples: neglected children, have the biological propensity to perform certain behaviours but because they have been denied the opportunity to practice them they acquire the behaviours much later than the peers, if at all.
• German children have the tendency to crawl later, due to German homes tradtitionally having wooden floors, therefore the environment makes crawling more difficult
• Chinese children are often placed on soft beds and therefore have more opportunity to practice locomotion as the environment is safe for them to get ample practice

Developmental milestones can be explained in terms of spontaneous emergence of new behaviours due to the reorganisation of previously acquired simpler behavioural components, known as self-organisation.

• An integrated system
• Non-linear/discontinuous: +ve, facilitates action, -ve, impedes action
• Transactional
• Self-organizing; system seeks future solutions to future problems which are most effective than past solutions
  • disruptions from the individual, task or new environment stimulate new behaviours
  • e.g. crawling is an action performed in a certain way dependant upon the environment
• In motor development, recurrence and repetition of behaviours due to action and perception gives rise to reorganisation of behaviour for coodination (Thelan, 1994)
• New behaviours are a product of the motivation to interact with the environment in more efficient ways, by anticipating future events. Maturation provides the foundation for this motivation to progress.

• Do infants need to understand the actions of others before they can understand the actions that they perform themselves?
• Do infants need to understand the actions that they perform themselves first in order to understand the actions of others?

Actions are understood in terms of goals and intentions.

e.g. the action anticipation in the foetus (Myowa, 2004)
Infants in the womb who displaying thumb sucking behaviours open their mouths before they put their thumb to their mouths, suggesting that they anticipate the movements they perform themselves at an early age.

Like-me Hypothesis (Meltzoff, 1997)

• Meltzoff suggests that infants perceive other humans as "like-me". Infants can therefore understand that there is a connection between perceived actions of others and performed acts executed by themselves. Repetition of action reinforces in infants the connection between action and their own mental states. Infants can them come to project their own mental states onto actions performed by others.

Common Coding Approach (Prinz, 1997)

• Prinz suggests that the to-be-performed actions, or aniticpated actions and the perception of actions performed by others share the same representational space.
• This is the understanding that seeing an event activates perception of the event, and performing an action activates the perception of the action in the mind also.

Imitation is the response by where an individual observes another's actions and replicates them themselves.

It is a complex behaviour, requiring numeruous interacting systems where the individual must:

• Observe the action
• Use visual information to source an action plan within themselves
• Manifest and execute the action plan behaviourally

Field (1982) suggested that imitation facilitates learning about behaviour in relation to it's goals.

Meltzoff (1977) found that young infants imitate facial gestures indicating that infants make cross-modal references between the actions and perceptions of others and themselves.

Woodward (1998) used habituation studies to show that infants focus on the goal path of human actions. It is suggested that from a young age, infants understand that humans perform actions with intention.

• Infants were required to habituate to a human hand reaching to either the same path or the same object. It was also tested using a wooden rod, but no effects were found. It was found that infants looked longer when the human hand did not reach to the intended object as opposed to not reaching within the same path, suggesting that infants understand that humans, not inanimtate objects, have intentions behind the actions they perform

Sommerville (2005) suggests that the actions an infant performs themselves facilitates learning.

• Infants were either subject to the reach-first condition, where the children were allowed to freely interact with a toy, or the watch-first condition, where infants watched a video about the toy. Those infants in the reach-first condition focused more on the relation between the actors goals and intentions, that the children in the watch-first condition.

Exchange between action and perception is complex, but it is through action an perception that individuals come to understand the relationship between ourselves and others, actions, goals and intentions.