Why Do you Often Stop your Impulsive Behavior at the Last Moment?

Behavioral impulse and time pressure jointly influence intentional inhibition: evidence from the Free Two-Choice Oddball task

Intentional inhibition is a crucial component of self-regulation, yet it is under-researched, because it is difficult to study without external stimuli or overt behaviors. Although Free-Choice tasks have been developed, it remains unclear how two key design features (i.e., behavioral impulse and time pressure) affect their sensitivity to intentional inhibition. To investigate this, the present study developed a Free Two-Choice Oddball task, which generated both an inhibition rate index and a response time (RT) index. Two experiments were conducted to systematically manipulate the ratio of the reactive standard to oddball trials and reaction time limit, inducing diverse behavioral impulses and different time pressures. The following findings were obtained from the critical Free-Choice trials. In the equal ratio condition, participants demonstrated comparable RTs for both the standard and oddball responses. In the moderate-ratio condition, participants exhibited longer RTs for the oddball than standard responses under low- but not high-time pressure. In the high-ratio condition, while RTs for the oddball responses were longer than those for the standard responses under both the high- and low-time pressures, participants displayed a decreased inhibition rate under the high-time pressure compared to the low-time pressure. Finally, participants exhibited a reduced inhibition rate in the high-ratio condition compared to the moderate-ratio condition. Together, these findings suggest that Free-Choice tasks can reflect intentional inhibition under specific conditions, and intentional inhibition is susceptible to both behavioral impulse and time pressure, while also establishing the theoretical and methodological foundations for subsequent research.

"Free won't" of food in overweight and normal-weight adults: Comparison of neurocognitive correlates of intentional and reactive inhibitions

Food-related inhibition plays a critical role in the manifestation of overweight. Previous research has focused exclusively on stimulus-driven (reactive) inhibition, which is different from intentional inhibition that refers to an internally generated decision to "stop". This study investigated the food-related neurophysiological correlates of intentional and reactive inhibitions in overweight and normal-weight adults. We compared 35 overweight participants (OWs) and 34 normal-weight participants (NWs) on performance and electroencephalography-based measures during a food-related go/no-go/choose task. In this task, participants made reactive responses to an instructed go/no-go target or made intentional choices whether to execute or inhibit a keypress when presented with a free-choice target. Our results mainly showed, 1) for group-difference, N2a amplitudes of OWs were less negative than that of NWs in the intentional trials; 2) for source difference, N2a amplitudes were less negative in reactive condition than in intentional condition uniquely in OWs. Moreover, comparison across intentional responses revealed that P2 amplitudes in no-go trials were lower than in go trials. Additionally, a greater body mass index correlated with lower intentional no-go-P2 and reactive go/no-go-P2 amplitudes. These findings suggest that overweight is associated with deficits in food-related intentional inhibition, which is segregated from reactive inhibition. The individual differences in premotor inhibition during free-choice situations might provide an explanation for overeating behaviors in overweight adults' daily life. Further, our results refine the ERP marker of intentional inhibition from N2 to N2a, which could be an essential neural mechanism underlying the "free won't" of food in OWs.

Altered resting-state functional connectivity of medial frontal cortex in overweight individuals: Link to food-specific intentional inhibition and weight gain

Numerous findings from functional neuroimaging research suggest that overweight may be associated with alterations in reactive inhibition. However, there is a dearth of research investigating the functional connectivity that mediates intentional inhibition in overweight individuals. To explore this issue, 55 overweight and 45 normal-weight adults completed an assessment consisting of a resting-state functional magnetic resonance imaging scan, a behavioural task measuring food-specific intentional inhibition, and a 1-year longitudinal measurement of BMI change. A seed-based approach was employed to examine the group-difference of the resting-state functional connectivity (rsFC) of the medial frontal cortex (MFC) (dorsal fronto-medial cortex [dFMC], pre-supplementary motor area, and premotor cortex) regions involved in intentional inhibition. Compared with normal-weight adults, the overweight individuals exhibited higher rsFC between the MFC seeds and (i) cerebellum, (ii) postcentral gyrus, (iii) middle temporal gyrus, and (iv) posterior cingulate cortex, while lower rsFC strength were observed between MFC seeds and (i) putamen and (ii) insula. The overweight individuals with higher dFMC-cerebellum rsFC strength showed poorer performance in food-specific intentional inhibition and gained more weight a year later than those of normal-weight participants. Results suggested that altered functional connections between MFC and regions associated with reward and maladaptive eating may be key neural mechanisms of food-specific intentional inhibition in overweight status. Therefore, individuals are encouraged to make informed decisions about their health and reduce their consumption of obesogenic foods from the perspective of intentional inhibition.