Hypothesis Testing

Underlying Cognitive Factors

Rule-based category problems, tasks that are solved by explicit rules or strategies, require the formation and testing of hypotheses to determine the rule that best solves the problem. This involves a continual process in which initial hypotheses are progressively refined or discarded until a rule is generated that adequately classifies objects into correct groups. This is a complex process which may consist of loops that reconsider the original hypothesis that was formed to generate new hypotheses to test.

How does this complex hypothesis testing process occur in humans? Hypothesis testing relies on an array of cognitive processes that are often described broadly as executive functions. Executive functions encompass selective attention, working memory, and inhibitory/cognitive control. During rule-based category learning, hypothesis testing involves selective attention to identify an explicit rule (e.g., if A, then B) or a set of rules (e.g., if A and B, then C); working memory is engaged to maintain, manipulate, and update new hypotheses; and inhibitory control is required to ignore incorrect hypotheses and/or responses (e.g., if A, then B, not C).

The use of hypothesis-generated explicit rules to guide behavior is an ability that develops gradually over the course of childhood through young adulthood. In the visual domain, evidence has demonstrated that the development of successful rule-based category learning via hypothesis testing parallels the development of executive function cognitive processes. Recently, this line of research has been extended to the auditory domain. These studies along with several others suggest that young children can often solve simple rule-based learning problems as well as young adults. However, young children are considerably inferior to young adults at solving more complex rule-based problems. The current thinking is that the brain regions involved in executive function are not fully developed in young children and this is why they do not perform as well as young adults (detailed below). As one moves from young adulthood to middle age and older age, we again see declines in rule-based learning. This follows because the brain regions that mediate executive function show structural and functional changes and, in later age, decline.

Neurodevelopment of Hypothesis Testing

Executive function processes, which are known to underlie successful hypothesis testing, are mediated by a network of brain regions, such as the prefrontal and temporal cortices, the anterior cingulate cortex, and the head of the caudate. The prefrontal cortex (PFC) is especially critical, and it is not completely mature until early adulthood. There has been a considerable amount of research that has demonstrated that different regions of the PFC are involved in representing rules at different levels of complexity from single-dimensional rules to shifting between more complex multidimensional rules. For example, the orbitofrontal cortex has been found to be activated during the explicit association of stimulus and reward; the ventrolateral and dorsolateral PFCs are activated during more complex rule selection and formation (e.g., if A and B, then C). In solving tasks that require multiple rules to solve, the rostrolateral PFC has been implicated.

...