Response inhibition is a fundamental ability to withhold a prepotent response or stop an ongoing response (Barkley,
1999). Response inhibition is crucial for regulating behavior according to social norms and goal-directed behavior and preventing adverse outcomes from executing impulsive actions (Bari & Robbins,
2013). Deficits in response inhibition ability were observed in psychopathological and neurological disorders, such as schizophrenia (Enticott et al.,
2008), attention-deficit/hyperactivity disorder (ADHD, e.g., Wodka et al.,
2007), compulsive disorders (Penadés et al.,
2007), and autism (Geurts et al.,
2014).
Response inhibition is commonly described as an act of cognitive control or executive function that enables individuals to adapt rapidly to environmental changes (Barkley,
1997; Schachar et al.,
2000). Previous research on response inhibition has primarily focused on developing cognitive abilities, such as the association between response inhibition, working memory, and attention (for review, see Chambers et al.,
2009).
Comparatively less research focused on the potential contribution of motor control to response inhibition (for a relevant review, see Mostofsky & Simmonds,
2008). Refining motor processes and successful response inhibition can be attributed to motor experience and expertise (Mann et al.,
2007; Molina et al.,
2019; Zhang & Rowe,
2014). For instance, Simpson et al. (
2019) found that fine motor control was associated with inhibition, statistically explaining drawing skills. Similarly, developmental research has shown that response execution and inhibition improve throughout childhood (Williams et al.,
1999).
The link between motor control performance and response inhibition is also observed in neurodevelopmental disorders (Diamond,
2000). Individuals diagnosed with attention deficit\hyperactivity disorder (ADHD) often exhibit poor motor coordination and are prone to act impulsively (Wodka et al.,
2007). Similarly, individuals diagnosed with poor motor control, such as developmental coordination disorder (DCD), tend to perform poorly on tasks that require response inhibition (Leonard et al.,
2015). Although the link between motor performance and response inhibition is commonly observed, it is still poorly understood.
The impact of action’s perceptual effect on motor performance
An own-action–effect plays a vital role in motor control and sensorimotor processes (Elsner & Hommel,
2004; Miall & Wolpert,
1996; Wolpert et al.,
1995,
2011). Notably, a perceptual effect must first be registered as an own-action–effect to impact motor processes. A motor-based computational process, known as the comparator model, was suggested to be responsible for evaluating the causal relationship between a motor action and a perceptual effect (Frith et al.,
2000; Synofzik et al.,
2008). According to this model, motor-based sensory predictions are compared with the representations of the actual sensory feedback. A discrepancy between the predicted and the actual sensory feedback is computed and evaluated at a pre-conceptual sensorimotor level, and it is susceptible to physical properties of the perceptual effect, such as its temporal contiguity with the response (Blakemore et al.,
1999,
2002; Frith et al.,
2000; Wen,
2019; Wen & Imamizu,
2022). According to this model, a perceptual effect must be temporally contiguous with the response to be registered by the motor system as an own-action–effect.
Focusing on the motor outcomes of this process, previous work documented the promoting impact of an Immediate action–effect on the speed and precision of motor behavior (e.g., Eitam et al.,
2013; Karsh et al.,
2016,
2023). For instance, in a speeded reaction time task, a perceptual effect (a brief white flash) that follows immediately after the response (compared to a delayed action–effect, spatially unpredicted and No-effect) was repeatedly demonstrated to facilitate response times (Eitam et al.,
2013; Karsh & Eitam,
2015a,
2015b; Karsh et al.,
2016; Penton et al.,
2018; Hemed et al.,
2020; Karsh et al.,
2020; Tanaka et al.,
2021; Hemed et al.,
2022). Notably, the facilitating impact of an Immediate (compared to Lagged) action–effect on response times was independent of participants’ attentional engagement in the task (Karsh et al.,
2016) and the probability of the effect when the motor system was not involved (Hemed et al.,
2022). Accordingly, response facilitation in these tasks was suggested to result from the reinforcing impact of an Immediate action–effect on motor response selection processes (Hemed et al.,
2022; Karsh & Eitam,
2015b). Such facilitation effect was recently demonstrated to depend on a specific combination between the stimulus and the response (Tanaka et al.,
2021), indicating a promotive impact of an Immediate action–effect on the development of stimulus–response associations (e.g., Paulus et al.,
2012; Tanaka et al.,
2021).
The above studies indicate that an Immediate perceptual effect that follows a response (compared to a subtly Lagged action–effect) facilitates the selection of the relevant responses, possibly by enhancing the development of the stimulus–response association. However, whether and how it affects response inhibition is unclear. Investigating this question will advance our understanding of the link between motor control performance and response inhibition, which may provide important implications for understanding action control challenges.
How temporally contiguous action–effect may impact response inhibition
The Go/No-Go (GNGT) and the Stop-signal tasks (SST) are commonly used for measuring response inhibition, yet growing evidence suggests that they recruit different mechanisms (Dambacher et al.,
2014; Eagle et al.,
2008; Raud et al.,
2020; Schachar et al.,
2007; Sebastian et al.,
2013; Swick et al.,
2011; Verbruggen & Logan,
2008,
2009). In typical GNGT, participants are instructed to respond in trials where a frequent Go stimulus is presented and occasionally withhold their response in trials where a No-Go stimulus appears instead of the Go stimulus. Response inhibition performance in the GNGT can be calculated by the proportion of Go responses in No-Go trials. Unlike the GNGT, in the SST, the Go stimulus is always presented at the beginning of the trial, and the Stop signal occasionally follows the Go signal after a variable delay. Response inhibition in the SST can be measured by the Stop-signal response time (SSRT), which reflects the latency of the covert Stop process. SSRT can be calculated by subtracting the averaged Stop-signal delay (SSD), which indicates the time delay between the Go signal and the Stop signal at which the participant has a 50% chance of stopping their response from the averaged Go-RT.
Such methodological differences recruit different processes. In the GNGT, an automatic association can be developed between the Go stimulus and the Go response and between the No-Go stimuli and the No-Go response and further contribute to response inhibition without additional cognitive control resources (Schachar et al.,
2007; Schneider & Shiffrin,
1977; Verbruggen & Logan,
2008). In contrast, such an automatic association is less likely to develop in the SST because the Go stimulus is non-selectively presented in both the Go and Stop trials.
For example, investigating the contribution of automatic stimulus–response (S–R) association to response inhibition in the GNGT, Verbruggen and Logan (
2008) asked participants to perform a semantic judgment (e.g., living or non-living). The requirement for a response was determined by the stimulus category (e.g., living as go and non-living as no-go). After a training phase where the S–R association was developed, participants performed a test phase where the Go and No-Go categories were consistent or inconsistent (e.g., non-living as go and living as no-go) with the training phase. Supporting the contribution of automatic S–R association to performance, in the inconsistent condition, RT was slower for stimuli associated with No-Go in the training phase (compared to new stimuli). In addition, in the consistent condition, success in no-go performance was higher for stimuli also appearing in the training phase (compared to new stimuli). These findings demonstrated the contribution of S–R association to automatic inhibition in the GNGT.
As indicated above, the S–R association is less likely to contribute to automatic inhibition in the SST where the Go stimulus appears in both the Go and Stop trials. Response inhibition in the SST is commonly attributed to cognitive control and explained by the influential horse-race model for response inhibition (Logan & Cowan,
1984; Verbruggen & Logan,
2008,
2009; Bissett et al.,
2009; Littman & Takacs,
2017). The model proposes that response inhibition is determined by the outcome of a competition between two independent processes: a motor response activation and a cognitive response inhibition. In this model, faster responses are more likely to “win” the competition and escape inhibition.
In the context of the current study, a previous work by Tanaka et al. (
2021) suggests that an Immediate action–effect enhances stimulus–response association. Specifically, the authors developed an adapted version of the ‘Effect-Motivation’ task (Eitam et al.,
2013) to investigate whether an Immediate (compared to 600 ms Lagged) action–effect reinforces the specific response, the stimulus, or stimulus–response association. Their findings demonstrated that the facilitating impact of an Immediate compared to Lagged action–effect on the speed of response selection depends on a particular combination between the stimulus and the response, potentially reinforcing the stimulus–response association and contributing to the refinement of sensorimotor representations.
Important for the current study, such enhanced stimulus–response association may also contribute to automatic inhibition in the Immediate (compared to Lagged) effect conditions. For instance, an improved selective association between the Go stimulus and the Go response may facilitate Go responses following the Go stimulus and reduce the probability of Go responses to other stimuli (e.g., the No-Go stimulus), contributing to a higher rate of successful inhibitions in the GNGT.
Preliminary evidence that an Immediate action–effect contributes to No-Go performance comes from our unpublished study using a free-choice paradigm where participants performed a modified version of a speeded reaction time task (Eitam et al.,
2013). Participants were required to respond as fast as possible to descending circles on their computer monitor. In some trials, a rectangle occasionally replaced the circle Go stimuli, indicating that participants should decide ‘freely' whether to respond in that trial. Consistent with previous studies (e.g., Eitam et al.,
2013; Karsh et al.,
2016), their RTs on Go trials were shorter when an Immediate (compared to 450ms delayed) effect followed their responses. Intriguingly, the proportion of their No-Go behavioral decisions was nominally higher in the Immediate compared to the Lag effect condition. Although this study was not designed to measure response inhibition directly, it empirically motivated the present study’s predictions that temporally contiguous action–effect will facilitate the speed of responses and increase the rate of successful No-Go trials.
Notably, previous theoretical and empirical accounts suggest minimal involvement of non-motor and controlled processes (e.g., monetary incentives, general motivation to succeed in the task, and conscious considerations; Eitam et al.,
2013; Karsh & Eitam.,
2015a,
b; Karsh et al.,
2016; Tanaka et al.,
2021; Karsh et al.,
2020; Hemed et al.,
2022) in the facilitating impact of an action’s immediate effect on RT. Therefore, we expected action–effect temporal contiguity manipulation in the current study will tap into sensory and motor processes with a minimal impact on controlled processes (e.g., Hemed et al.,
2022; Karsh et al.,
2020). Accordingly, we hypothesized an Immediate action–effect would facilitate Go response speed and improve automatic inhibition performance in the GNGT but not inhibitory control performance (SSRT) in the SST. We integrated the GNGT (Experiment 1) and SST (Experiment 2) with the Effect–Motivation task (Eitam et al.,
2013), previously established to measure the impact of action–effect temporal contiguity on RTs. In both experiments, action–effect temporal contiguity (Immediate vs. 450 ms Lagged action–effect) was manipulated in different blocks in a within-subject design. Consistent with previous studies (Eitam et al.,
2013; Karsh et al.,
2016; Tanaka et al.,
2021), we expected RTs in Go trials would be shorter in the Immediate compared to the Lag effect condition in both tasks. Importantly, we also expected a better No-Go performance in No-Go trials in the Immediate compared to Lagged effect conditions (Experiment 1) and that SSRT would not be affected by action–effect temporal contiguity in the SST (Experiment 2). However, we expected the average SSD to be smaller in the Immediate than in the Lag effect condition, reflecting the race between the Go and Stop processes (see pre-registration:
https://osf.io/dc93t/?view_only=14f9f30baeb1462b927121e155222186).