Broadly speaking, inhibitory control is the ability to suppress the activation, processing, or expression of information that would otherwise interfere with the efficient attainment of a cognitive or behavioral goal. Everyday examples of inhibitory control include a student who must ignore the conversations of her siblings while she is trying to study for an exam, a baseball player who starts to swing at a pitched ball but then attempts to stop his swing, and a small child who must ignore all of the extra visual information when he is searching for Waldo in his Where’s Waldo book. Given the countless sources of interference encountered on a moment-by-moment basis, intact inhibitory control is essential for navigating and effectively interacting with the environment.
Although inhibitory control involves many regions of the brain, past research suggests that one particular region, the prefrontal cortex (PFC), plays an essential role in the mediation of inhibitory control. Evidence from studies such as the one conducted by D. Guitton and colleagues supports this notion. The researchers administered a task designed to measure inhibitory control to three groups of individuals: people who had previously experienced injury to the PFC, people who had previously experienced injury to parts of their brain other than the PFC, and people who had no history of brain injury. The researchers found that people with PFC damage performed more poorly on the inhibitory task than the other two groups. This finding supports the notion that the PFC is very important for efficient inhibitory control.
Additional support for the role of the PFC in inhibitory control is evident in the early development literature. Specifically, the emergence of proficient inhibitory control during childhood parallels the maturation of the PFC. The PFC and its connections with other brain regions are the last brain structures to reach maturity. Whereas most other regions of the brain reach adultlike levels of development by 12 years of age, the PFC continues to mature for several additional years. A similar pattern of improvement is observed on tasks requiring inhibitory control well into young adulthood.
The importance of the PFC in the development of inhibitory control is further underscored by the fact that inhibitory deficits have been observed in a range of childhood disorders, including attention deficit/hyperactivity disorder, Tourette’s syndrome, obsessive-compulsive disorder, and childhood-onset schizophrenia. Although the specific etiology of each of these disorders is unclear, in each instance it is believed that damage occurs during PFC development, and abnormal neural activity in the PFC and/or structural PFC abnormalities have been observed for individuals with each disorder.
Present research efforts are focused on several topics related to inhibitory control. For example, work is currently underway investigating the relationship between inhibitory control and other cognitive abilities such as working memory and processing speed (how fast your brain can process information). Understanding the interplay between abilities like these and learning how each of these abilities develops can provide invaluable insight into the overall intellectual development of humans throughout childhood. Other researchers are exploring the possibility that several different subtypes of inhibitory control may exist. Using a combination of behavioral and neuroimaging studies, researcher B. J. Casey has taken a lead in this area of study. She has recently proposed that five different subtypes of inhibitory control may exist, with each type being supported by a different brain pathway. While Casey’s model remains speculative at this time, it provides a nice starting point for future research in the area of inhibitory control.
- Casey, J., Tottenham, N., & Fossella, J. (2002). Clinical, imaging, lesion, and genetic approaches toward a model of cognitive control. Developmental Psychobiology, 40,237–254.
- Christ, E., White, D. A., Mandernach, T. B., & Keys, B. A. (2001). Inhibitory control across the life-span. Developmental Neuropsychology, 20(3), 653–669.
- Dagenbach, , & Carr, T. H. (1994). Inhibitory processes in attention, memory, and language. San Diego, CA: Academic Press.
- Dempster, N. (1992). The rise and fall of the inhibitory mechanism: Toward a unified theory of cognitive development and aging. Developmental Review, 12, 45–75.
- The Nemours F (n.d.). What is ADHD? Retrieved from http://www.kidshealth.org/parent/medical/learning/ adhd.html