Unconscious Inhibitory Control

Inhibitory control refers to the executive control for the habitual ongoing actions or interference, which can lead the limited cognitive resources to the goals or other important tasks. Inhibitory control can enable the limited cognitive resources focus on the special targets; reduce the useless influence of the automatic responses or unrelated information on the targets, so as to increase the behavior efficiency and the success probability of the goal. Inhibitory control as an important component of the cognitive control plays an important role in the senior executive functions. For a long time, inhibitory control is regarded as a process of consciousness; it is mostly become a meaningless question for whether or not exists unconscious inhibitory control. Previous studies have shown that the prefrontal cortex is the most important neural basis of cognitive control, and PFC responsible and execute the inhibitory control functions. Prefrontal cortex is also considered to be a major area for generating consciousness. Which seems to suggest that the inhibitory control is a conscious processes, does not exist the unconscious inhibitory control and the unconscious stimuli also can’t activate the processes of the inhibitory control. However, several recent studies challenge this view, researchers found in the related studying that was be effectively masked subliminal control signals can significantly prolong the participants’ reaction time, at he same time, these stimuli can activate the frontal lobe "inhibitory control network". It’s really exists the unconscious inhibitory control? Do the unconscious stimuli can activate the inhibition process? Does the subliminal information really can activate the inhibitory control network of the prefrontal cortex? Now, for the above questions have become the unconscious studying hotspots.Currently, the masked priming paradigm always was used to researching the unconscious inhibitory control. Early, Sumner et al (2007) using the masked priming paradigm to study the process of unconscious inhibitory control, results indicate that subjects who’s supplementary eye field and supplementary movement area destroyed have a abnormal performance in the inhibitory control task, but the normal participants put on a response delay to the conflict situations. Go/no-go paradigm is an effective experimental way to study the cognitive control. Some researchers combined the go/no-go paradigm with the masked priming paradigm for researching the unconscious inhibitory control process; the results show that the unconscious "no-go" signal activated the prefrontal inhibitory control neural circuits. But the studying for the unconscious inhibition has just started, there are many issues need to be resolved. Due to the limitation of experimental methods, in the previous studies the experimental effects were be affected by the practice effects. S-R connection strength between the stimuli and the responses would directly affect the subsequent experiment results. It’s easily to operate that using the conditioned reflex for studying the unconscious inhibitory control, but the task is too boring to mobilize the subjects’interesting. Furthermore, the conditioned reflex also will limit the information processing level of the unconscious stimuli. In addition, unconscious inhibitory control is generally regarded as a bottom-up, stimulus-driven information processing. However, research in related field found that unconscious information processing is susceptible to the top-down attention mechanisms, which challenges the traditional view of the unconscious automatic processing. According to the theory of the relationship between conscious and attention by Dehaene et al, top-down selective attentions can amply the unconscious information processing, and improve the information processing level. Does the top-down attention mechanism can also influence the unconscious inhibitory control process?/Whether the top-down attention mechanism can also affect the unconscious inhibitory control process?Based on the above problems, this study proposes two experimental hypotheses:1. the unconscious cues can induce the inhibitory control process.2. Unconscious inhibitory control is not just a bottom-up, stimulus-driven information processing, the process of unconscious inhibitory control is easily affected by the top-down attention mechanism activated by goals, task demands and so on, the study adopts the go/no-go experimental paradigm and develop it, new paradigm using game task replace the conditioned reflex task and inhibitory control task. New paradigm add a interference stimulus as background information based on the original "go" signal and "no-go" signal. Experiment neither rewards nor punishments to the interference stimulus, setting the interference stimulus aims to improve the difficulty of information processing in the unconscious inhibitory control process. Because the experiment will appear different feedbacks according to the subjects" reactions and subjects can receive rewards from playing the game task, so this experimental task is better to mobilize the subjects’ positive, but also simplifies the experiment task and avoid the possible negative impact of the practice on the unconscious inhibitory control process. Experiment1asked participants rapidly guess what king of the stimulus that was be effectively masked by the mask stimulus; participants must estimate the masked stimulus is reward signal, punishment signal or interference signal. Experimental instruction has told the forms of the three kings’ stimuli and each others’ meanings before playing the game task. When participants each make a judgment will be given a timely feedback. Experiment2made an adjustment to the experimental instruction in order to investigate the influence of the top-down attention mechanism for the unconscious inhibitory control. Different from the experiment1, the introduction of experiment2no longer tell subjects the forms of three cues and their meanings. Just tell participants there are three cues:reward signal, interference signal and punishment signal. So participants need to according to the feedback information timely adjust their reaction, and keeping on learning by the continual trying. Besides, participants need to finish a perception discrimination task before the formal game task, which is to exam the visibility to the masked stimuli. If does not significant difference between the performance of perception discrimination task and the random probability, The cues information processing process will be considered is unconscious.This experiment is a3(stimulus types:reward/penalty/interference) x2(instructions:active/passive receiving) x2(response delay:Oms/500ms) mixed design.90college students participate in the study,60college students among them taken part in the experiment1; another30students join in the experiment2. The results of experiment1show that, even in the case of the stimuli can not be perceived, participants’reaction time to the penalty stimulus was also significantly longer than reward stimulus and interference stimulus. Under the delay condition (delay=500ms), reaction time (RT) to penalty signal was also significantly different from the reward signal and interference signal. RT to the penalty cue is longer than the reward cue, but the difference is not significant. Experiment2found that under the condition of the instruction does not prompt the forms and meanings of these cues the difference of reaction time to three kings of signal stimuli was not significant. RT to the interference stimulus is longer than penalty stimulus and reward stimulus, but the differences were not significant. Based on the results of the experiment1and experiment2, it can be concluded that unconscious stimuli can induce inhibitory control behavior. The unconscious inhibitory control vulnerable to the impact of the top-down attention mechanisms, unconscious inhibition is not only the stimulus-driven, bottom-up information processing process.