A major difficulty in developing views about knowledge is that we are speculating about what goes on in people’s heads. Brain scientists and neurologists have worked out which parts of the brain have particular roles, and can map brain activity when certain tasks are undertaken. We know that neurons (nerves in the brain) can form many interconnections with other neurons, and that the more frequently connections are used, the “stronger” they become; just as a path can be worn in grass by many feet passing the same way. But this is only telling us about the physical. While it gives us clues about how knowledge is arranged and stored in the brain, how it is retrieved, and how it is added to, the picture is very incomplete. So we must rely on some theories about this, which are consistent with both the physical evidence, and studies of human learning. We cannot pretend that this book is about psychology, so we will only refer to those theories that we think are contemporary, have currency in science education, and are helpful to science methods instructors. Schema theory gives us one way of thinking about knowledge organization and extension (epistemology) that is very useful.
Schema Theory
The key idea of this theory is that our past experiences are linked mentally in our memories, to form an organized structure of ideas, which psychologists call a cognitive structure. It is postulated that experiences are stored in the memory as separate events, but those having some commonality are linked in clusters. These clusters form an idea, consisting of multiple links across a network of experiences. Similarly, ideas with commonalities are linked to each other forming a complex network of linked ideas and experiences. These are often represented diagrammatically by Venn diagrams or concept maps.
A network of mental ideas centered round some commonality is called a schema (the plural of this Latin word is schemata). Often the anglicized version of the word, scheme (plural, schemes), is used. An example of a schema would be a simple concept like “duck.” Imagine, if you will, a young child walking past a pond with a parent, pointing to a white bird swimming on the surface, and asking, “What’s that?” The parent’s answer, “A duck,” allows the child to store in memory the word and the visual impression of a swimming white creature. They later encounter a white swan on the pond, and the child points, exclaiming “Duck!” The parent responds, “No dear, that is a swan. See, it has a long neck, and is a lot bigger than the duck.” The child processes this information, forming in her mind links between this experience and the earlier memory of “duck,” specifically linking to remembered aspects of neck length and body size. They later encounter a Mallard duck, and again there is an exchange where the parent patiently points out the differences and similarities between this duck, the white duck and the swan. In this way, the child builds a network of memories of different water birds and their language labels, with specific differences and similarities noted. A schema of “duck” is being constructed, with links to other schemata centered round “swan,” and perhaps later, “goose.” Each of these schemata is in turn linked to the others to form a general schema of water birds, and more generally, one of birds.
Notice in the above example, the notion that schemata are constructed. This is an important idea when we come to look at learning theories. Construction is a subconscious activity, but it does require deliberate attention to experiences and information extracted from them. Also, note that networks between schemata are constructed, linking those with similarities, and often forming more general schemata. Network construction is also a subconscious activity, which still requires attention to experiences, remembered experiences, and information embedded in them. Finally, note that new information gathered from experiences via the senses is incorporated into memory by association with existing schemata.
This process of making links between experiences and ideas can be considered as analogous to neurons in the brain forming links to other neurons—though perhaps in very different parts of the brain. According to this view, then, at some point soon after neuron development in a baby begins, the neurons start forming links with other neurons. Some links endure; some fade. As sensory organs begin to deliver information to the brain (such as sound penetrating into the womb), simple schemata begin to develop. As the brain receives new information the schemata are modified and extended. This process continues as the child grows. There is evidence to suggest that neuron growth (or at least replacement) continues throughout life, and that there are a couple of periods of rapid neuron growth in children.
Schema theory also provides a perspective on what happens when we remember something. A sensory stimulus that occurs in a particular context is linked to a schema selected by the brain. This both helps us interpret the stimulus, and activates a string of memories related to that schema: those memories have been recalled. Problems in recall can occur if the brain selects a different schema that activates a different set of memories, or if the link to a particular memory has faded.