Response inhibition and associative learning: Training stimulus specific response inhibition

Abstract

Response inhibition, which refers to the ability to cancel an already initiated motor response, is often considered to be a hallmark of Executive Control. The popular view conceptualises these control processes as deliberate and top-down. How- ever, what if you have cancelled the same response (say stopping at a pedestrian crossing) to a given stimulus (in this example the red do not cross pictogram) many times before? Does the resulting action cancellation remain an exclusively top down act of control, or does it become bottom-up with practise. Research suggests that repeatedly pairing a stimulus with withholding a response results in slowed reaction times and a decreased probability of responding, even when no longer appropriate (a phenomenon first reported by Verbruggen & Logan, 2008a). This thesis attempts to answer this question from an associative learning per- spective: Asking if repeatedly pairing a stimulus with action cancellation results in stimulus-stop associations. Chapter One introduces current perspectives on response inhibition, the dual- process model of associative learning, and a theoretical framework that attempts to integrate these areas. Chapters Two and Three ask what is learnt when a stimulus is repeatedly paired with stopping in response inhibition task: Specif- ically, Chapter Two investigate the contribution of stimulus detection. Chapter Three asks whether subjects are learning not to respond or withhold and pro- vides evidence for the feature-positive effect in stimulus-stop learning. Chapter Four investigates the role of explicit expectancies and incidental associations in this form of learning, whilst also exploring whether transcranial direct cur- rent stimulation can enhance the acquisition of stimulus-stop associations. Both Chapters Five and Six investigate how stimulus-stop training may transfer to other tasks and behaviours with a specific focus on why stimuli tend to be devalued after stimulus-stop training. Finally, Chapter Seven relates the findings of each respective chapter back to the theoretical model introduced in Chapter One.