Inhibitory Control and Response Inhibition

Inhibitory Control

• Inhibitory control involves suppressing thoughts or actions that are no longer needed or inappropriate.
• It is essential for adaptive behavior.
• Examples include stopping a car at a red light or avoiding a busy intersection.

Response Inhibition

• Response inhibition is the deliberate stopping of a motor response.
• It often involves interrupting an ongoing action or activity.
• Real-world examples include stopping a response when instructed or refraining from crossing a busy intersection.
• In a lab setting, this could involve pressing a response key.

Stop Signal Procedure

• This procedure studies response inhibition in a lab setting.
• Subjects complete a primary task (a "go task"), and respond to stimuli.
• On some trials, a stop signal is given (e.g., a tone), which indicates the subject should withhold their response.
• Stop signal delay (SSD) is the interval between the go stimulus and the stop signal.
• Stop signals occur randomly, on a minority of trials (e.g., 25%).

Stop Signal Procedure Measures

• Go Reaction Time (go RT): Time it takes to respond to a go stimulus.
• Probability of stopping, p(inhibit | signal): Proportion of stop signal trials where a response was successfully inhibited.
• Probability of responding, p(respond | signal): Proportion of stop signal trials where there was failure to inhibit a response.

Balancing Going and Stopping

• Success in the stop-signal procedure involves balancing competing task demands.
• Increased speed in going actions make stopping harder; proactive and reactive adjustments are used to balance.
• Increased speed in going actions needs to be balanced with the ability to stop when necessary.

Proactive Adjustments

• Adjusting a go response to increase stopping success.
• Prolonging go RT when SSD increases.
• This method is shown when two lights are used with different reaction times, in response to a stop signal, or no signal.

Reactive Adjustments

• Adjusting the go response based on previous stopping performance.
• The go reaction time increases after a stop signal, whether successful or not.
• Adjusting the reaction time based on prior trials/results.

Independent Race Model

• A model used to estimate SSRT (Stop Signal Reaction Time).
• Assumes a race between a "go" process and a "stop" process.
• The process that finishes first determines the behavior.

Inhibitory Control Development

• Inhibitory control develops across the lifespan.
• Studies have shown a relationship between age and SSRT with reaction times improving up to a certain age, before changing little in adulthood.
• Suggesting separate development and decline in going and stopping respectively.

Inhibitory Control Deficits

• Deficits in inhibitory control are associated with various disorders.
• One prominent example is ADHD (Attention-Deficit/Hyperactivity Disorder).
• Individuals with ADHD often experience difficulties with sustained attention and maintaining responses.
• Studies have shown poorer stopping reaction times for children diagnosed with ADHD, compared to healthy controls.

Summary of Inhibitory Control

• The stop-signal procedure is a key method to test inhibitory control.
• Proactive and reactive adjustments enable a balance between "going" and "stopping" actions.
• Independent race models provide a framework for measuring SSRT (Stop Signal Response Time).

This quiz explores the concepts of inhibitory control and response inhibition, essential for adaptive behavior. By examining real-world and lab examples, participants will deepen their understanding of how inhibitory mechanisms operate in various contexts. Test your knowledge about how these processes affect decision-making and action suppression.