Executive Function and the Developing Brain
The idea that people are either conscious of something or they’re not seems like common sense. However, research into the development of the prefrontal cortex — the area of the brain responsible for executive function — shows that this assumption is not necessarily true.
APS Fellow Philip Zelazo, from the Institute of Child Development at the University of Minnesota, discussed this seeming paradox in his invited address, “Executive Function and the Developing Brain.” Zelazo defined executive function as the “processes or functions involved in goal-directed cognitive control of thought, action, and emotion.” Executive function complements intelligence: it has to do with applying knowledge toward goal-directed behavior. It emerges in late infancy and continues to develop throughout adolescence, although much development occurs during preschool ages (2–5 years).
The performance of 3- and 4-year-old children on the Dimensional Change Card Sort task provides a revealing example of the development of executive function. In this task, children are shown two target cards depicting objects, such as a red car and a blue flower, and then asked to sort bivalent test cards such as a blue car and a red flower. Children are first asked to sort objects by a particular dimension (e.g., shape). After completing this first task, children are then asked to sort the same objects by a second dimension (e.g., color).
What researchers, including Zelazo, have found is that 3-year-old children have no problem sorting the objects by the first criterion they are given; however, when asked to sort by a second criterion, they continue to sort by the original instruction. Curiously, this occurs even though it is clear from the children’s responses to questions that they understand the new instructions. So, when asked, “Where do the red ones go in the color game?” they respond correctly. When then shown a red flower and told, “Play the color game,” however, they perseverate and sort the object by shape. In contrast, when 4-year-old children are given the same tests, they have no difficulty adjusting to a second instruction.
The difference in performance between these two age groups seems to be attributable to the varying levels of consciousness the children can access to categorize tasks. Three-year-old children consciously formulate a rule governing the initial task they are presented with. When given a second task regarding the same objects, they may develop a corresponding second rule, but they do not further reflect on those rules, consider them in relation to one another, and formulate a higher rule that integrates and governs the application of the two lower-level rules. By the time they reach the age of 4, however, children begin to think at higher levels of consciousness, so they are more likely to group related rules together and develop a metarule to govern them. This allows them to choose between varying rules and act appropriately in different situations.
So, in contrast to the common-sense notion that we are conscious of something or not, Zelazo points out that “we may be conscious of something at one level but not at a higher level.” Adults, for example, access different levels of consciousness according to the changing needs of the situation. Their ability to do so, however, initially develops in the early years of life.
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