Mechanisms of Development


What drives development?
Gibson believed that development was driven by a complex interaction between environmental affordances and the motivated humans who perceive them. For example, to an infant, different surfaces "afford" opportunities for walking, crawling, grasping, etc. As children gain motor skills, they discover new opportunities for movement and thus new affordances (Miller, 2002). The more chances they are given to perceive and interact with their environment, the more affordances they discover, and the more "accurate" their perceptions become.

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Developmental processes across the lifespan

  • Gibson's theory does not specify stages at which people develop specific perceptual skills
  • Gibson's research primarily focuses on perceptual milestones in infants and young children and does not make predictions about milestones in later childhood development or adult development
  • Overall, as children develop, perception becomes more "specific and economical," and attention also becomes more selective. Thus children learn to recognize the most distinctive features of objects and their most relevant affordances. (Miller, 2002)
  • Perception becomes more efficient through three developments:
    • Distinctive features: children learn to discriminate between objects and stimuli by focusing attention on their most critical properties
    • Invariants: children learn to extract aspects of objects that remain permanent despite change (e.g., as an object moves)
    • Structure: the world has an inherent structure that people gradually become more aware of as they develop. Although previous researchers thought that humans "enriched" ambiguous and uninformative perceptual information using cognitive processes, Gibson viewed the environment as rich with information, with the primary developmental task being the differentiation of this information into affordances.
  • Key milestones found in Gibsonian empirical research:
    • Two-day-old infants can recognize their native language (Moon, Cooper, & Fifer, 1993, in Miller, 2002)
    • At 4 1/2 months, infants are able to perceive the separateness of objects (Miller, 2002)
    • However, at 4 months, infants still perceive separate objects as united if they move together (Miller, 2002)
    • At 4 months, infants can also distinguish between male and female; when hearing a female voice, they look toward a female face, and vice versa (Walker et al., 1991, in Miller, 2002)
    • At 5 months, infants can discriminate between a live video of their legs and a video of another infant's legs or a pre-recorded video (Bahrick & Watson, 1985, in Miller, 2002)
    • At 7 to 9 months, infants can match the sound of an instrument to a musician playing that instrument (Pick et al., 1994, in MIller, 2002)
    • As infants gain crawling expertise, they learn to distinguish between dangerous slopes and slopes that are within their capabilities (Adolph, 1997, in Miller, 2002)
    • But experience with an earlier-developing skill does not transfer automatically to a later-developing one.
      • Experienced "sitters" at 9 months avoided a risky gap, but when crawling (a new skill), they fell into the risky gap (Adolph, 2000, in Miller, 2002)
    • From ages 4-8, children are increasingly able to perceive distinctive features of objects
      • Younger children have trouble distinguishing between different letters of the alphabet (e.g., M and W), but older children are able to make this distinction more easily (Gibson et al., 1962)
  • Late in her career, Gibson (1988) described general "phases" of neonate development. She stressed that these were nothing like Piagetian stages and that they overlapped significantly. This late attempt to describe phases was never fully incorporated into Gibson's theory, and the phases were not used in subsequent literature or research.
    • Phase 1 (Birth-4 Months): Infant focuses on immediate visual surroundings, but pays little attention to objects. Sounds are attended to more consistently.
    • Phase 2 (5-8 Months): Attention to objects. Grasping, increased visual acuity, depth information allow infants to discover affordances and distinctive features of objects.
    • Phase 3 (8-9 Months-1 year): As infant becomes ambulatory, attention is directed toward larger environment. Affordances for movement (hiding, playing, etc.) are discovered.
    • After first year: Gibson states that research after the first year is "scanty" and neglects to define any phases or further developments in human perception.

In what phase of neonate development is this baby? What affordances might she perceive for this object?
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The video below is a recent study on perceptual learning in children.** Notice how changing the babies affordances (giving them velcro gloves) changes the information they attend to in their environment.



Connections between early and later development


According to Gibson, perceptual learning was persistent through the lifespan and plays an important role in cognition. Indeed, she even went so far as to say perception is the "primary process" that makes cognition possible (p. 178, Gibson & Pick, 2000). She believed cognitive processes such as imagining and reasoning developed in proportion to the amount of information we gathered from the environment.

What does change as we grow is not how we learn (through perception), but what learn. For example babies come into the world programmed to pay attention and be responsive to human voices and faces. Later they learn about objects and even later locomotion. Beyond infancy, learning becomes more specialized (i.e. acquiring language, how to use a spoon, etc). These specialized tasks have their roots in more basic ones. (Gibson & Pick, 2000)

The table below provides examples of perceptual tasks and compares development in infancy to what happens as a child continues to grow. The information in the table is a summary of information from Gibson and Pick (2000).

Perceptual Learning Task

Development in Infancy

Development Beyond Infancy

Speech

Infants quickly become attune to their nativelanguage. Even fetuses are attuned to their native tongue. Within the first year, infants will lose sensitivity to sound patterns not in their language and begin to differentiate
patterns in their own.
In later development infants will learn to differentiate symbols representing speech and thus learn to read.It could be hypothesized then that infants who have trouble differentiating speech will struggle with talking and reading later in life.

Manual Skills and Tool Use

Beginning around 4 months infants can
reach for objects, pick them up, catch them,
and eventual handle them. As infants gain
more control of their motor skills they
develop more advanced manual skills (i.e.
using a spoon for eating). Tool use is
also often learned through observation
(social environment/affordance).
Motor development and tool use becomes more and
more specialized throughout a human's lifespan.
Motor development may later depend on the activities we pursue or our career. For example, an athlete will perceive different affordances based on the environment of their sport and develop their motor skills according (i.e. a baseball player will learn how hard to hit a ball depending on if he/she wants to put it in the outfield or bunt it).

Locomotor Skills

Gibson notes a study by McGraw (1935) in
which twin boys, Johnny and Jimmy were
studies. Johnny received training and went
through exercises daily involving different
motor skills (i.e. lifting head, rolling over,
sitting, etc). Despite Johnny's training,
Jimmy and Johnny's development of
these skills (i.e. sitting and walking)
emerged at the same time. Johnny did
seem a little more smooth and confident.
This experiment showed how children
will teach themselves, even when specific
training is not given.
The example Gibson provides can be applied to later
development as well. Using the example of athletes
again, we know that athletes often gain skills more
deliberately than babies. They also may use models
to learn certain skills, but perceptual learning
remains an essential part of the process.

Conceptual Development

While some researcher's believe concepts
only develop with symbolic representation
(i.e. language), Gibson argues that infants
form concepts before they can even speak.
She claims that concepts develop in infants
by experiencing the same affordance
several times. Then the infant learns to
generalize the experience. For example,
3 to 4 month old infants seem to be able
to discriminate between cats and horses
(Bomba &Siqueland, 1983).
Gibson argues that perception continues to be an
important part of cognition at all ages. She would
say that our abstract symbols and ideas come from
our perceptions and experiences of the world, and
develop before we even have words to name these
things.

Methodology

Gibson used experimental procedures while also attempting to retain ecological validity by simulating important features of the child's natural environment. In keeping with the idea of affordances, Gibson tried to provide multimodal stimulation for infants in these experiments (e.g., multiple kinds of objects, faces, or surfaces) and ways of obtaining feedback through movement and exploration (Miller, 2002).

One of Gibson's most famous perceptual experiments involved the construction of a "visual cliff," which simulated the appearance of a real cliff. Gibson and Wall (1960) placed infants near the cliff and placed mothers on the other side of the cliff. They found that infants perceived depth and were unwilling to crawl over the cliff at approximately 6-7 months. Later experiments showed that 12-month-old infants had learned to use their mothers' facial expressions as signals of potential affordances. If mothers smiled, infants were more likely to crawl over the "dangerous" cliff, but if mothers made a frightened face, infants avoided the cliff (Sorce et al., 1985).