Abstract
This study measured proactive and reactive response inhibition and their relationships with self-reported impulsivity. We examined the domains of both vocal and manual responding using a stop signal task (SST) with two stop probabilities: high and low probability stop (1/3 and 1/6 stops respectively). Our aim was to evaluate the effect stop probability would have on reactive and proactive inhibition. We tested 44 subjects and found that for the high compared to low probability stop signal condition, more proactive inhibition was evident and this was correlated with a reduction in the stop signal reaction time (SSRT). We found that reactive inhibition had a positive relationship with dysfunctional but not functional impulsivity in both vocal and manual domains of responding. These findings support the hypothesis that proactive inhibition may pre-activate the network for reactive inhibition.
Highlights
This study measured response inhibition via the stop signal paradigm (Vince, 1948; Lappin and Eriksen, 1966; Logan and Cowan, 1984) in two effector systems: vocal and manual
We propose that the lack of a relationship could have been due to the amount of proactive inhibition that was used in these tasks: while in their first experiment proactive inhibition was measured as a slowing of go reaction times (RTs) of 111.3 ms for the relevant compared to an irrelevant stop condition, in the third experiment this difference was only 55 ms
The results revealed that all three factors were significant: response modality [F(1, 43) = 46, p < 0.0001, N2p = 0.52], stop probability [F(1, 43) = 1.2, p < 0.0001, N2p = 0.82] and RT type [F(2, 86) = 83, p < 0.0001, N2p = 0.66]
Summary
This study measured response inhibition via the stop signal paradigm (Vince, 1948; Lappin and Eriksen, 1966; Logan and Cowan, 1984) in two effector systems: vocal and manual. The analysis of the stop signal task (SST) is based on the horse race model proposed by Logan and Cowan (1984). The model assumes that the stop and the go processes are independent of each other in the sense that whichever finishes first, wins. This assumption is based on the fact that failed stop trials always have faster mean reaction times (RTs) compared to go trials, suggesting that participants fail to stop because the go process finishes before the stop process.
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