Inhibitory Devaluation Effect In Internet Addicts

The inhibitory devaluation effect refers to the phenomenon of reducing the valuation of a stimulus by inhibiting the attention,response,or recall of that stimulus.Studies have found that individuals have a reduced value assessment of suppressed stimuli compared to stimuli that are not suppressed.The valuation of things is an important factor in determining what behaviors individuals adopt toward them,and starting from valuation devaluation may help to reduce individuals’ unhealthy behaviors.To reduce the value of Internet-related stimuli in Internet addicts through the inhibition of the devaluation effect,it is necessary to understand whether the effect can have the same effect on Internet addicts as on normal individuals.It is still unclear whether Internet addicts can achieve devaluation of stimuli or even show stronger devaluation effects from inhibiting responses to stimuli.In this study,we investigated whether Internet addicts could devalue the inhibited stimuli from the inhibition of stimulus-response,and explored the brain activity during the devaluation process,as well as the difference between the two groups by combining functional NIR imaging.The study used a mixed design of 2(group: IA group vs.Control group)× 2(responsestatus: Go vs.Stop),where the group was a between-subjects variable and response state was a within-subjects variable.The Internet Addiction Test(IAT)was used to screen the subjects,and individuals with scores of 80 and above were included in the IA group,and those with scores below 50 were included in the control group.A total of38 subjects participated in the study,including 18 in the IA group and 20 in the control group,with an average age of 20.660±2.044.The study was divided into three phases,and participants were required to complete three stages of tasks: the first stage was the learning phase,in which participants learned the value information of different shapes by reacting to shapes and obtaining monetary feedback.The second stage was the stopsignal task.A set of shapes was always paired with Go trials,and a stop signal never appeared in these trials.Another set of shapes was paired with a stop signal,and when a stop signal appeared,they needed to suppress the reaction to the shape.The third stage was the value assessment task,where participants needed to evaluate the shape that appears in the first two stages,and choose the amount from the given amount that best matches their subjective value judgment of the shape.During the second and third phases of the task,participants were required to wear NIR hats to collect fNIRS data on their brain activity.As for the behavioral results,the bidding levels of the two groups of participants in the value assessment phase were analyzed,and it was found that the main effect of the response-status was significant,and the participants’ bidding levels for the shapes associated with the stop-signals were significantly lower than those for the shapes associated with the Go trials.The interaction effect of group and response-status was significant,and the IA group’s bids for the shapes associated with the stop-signals were significantly lower than those for the shapes associated with the Go trials;from the analysis of the response-status,for the shapes associated with the stop-signals,the difference in bid levels between the IA group and the control group reached marginal significance,with the IA group having lower bid levels.The results indicated that both groups showed a devaluation effect to the suppressed stimulus and that the devaluation effect was stronger in the IA group.Regarding the fNIRS results,region-of-interest-based analysis of fNIRS data revealed that during the stop-signal task phase,an interaction effect between group and responsestatus was found in the left dorsolateral prefrontal cortex(L-DLPFC),with the control group showing lower activation for shapes associated with stop-signals than for shapes associated with the Go trials.During the value assessment task phase,in the right orbitofrontal cortex(R-OFC),activation in the control group was lower for the shapes associated with the stop-signals.The correlation analysis between the activation level of brain regions in the stop-signal task phase and the bid level in the value assessment phase showed that the bids for the shapes associated with stop-signals in the control group were significantly negatively correlated with the activation of brain regions in the DLPFC of the stop-signal task.In the IA group,the bids for the shapes associated with stop-signals were significantly negatively correlated with the activation in the OFC.What’s more,in the control group,the strongest correlation was found between the activation caused by stop-errors and the bids for shapes associated with stop-signals.In the IA group,the correlation between the activation caused by correct responses and the bids for shapes associated with stopsignals was higher than that of stop-errors.Finally,correlation analysis of activation levels in different brain regions during the stop-signal task phase with activation levels during the value assessment phase showed that brain activation in both phases in the control group was positively correlated overall and mainly reflected a significant positive correlation across brain regions.Whereas,in the IA group,there was no significant correlation between activation under all conditions and brain regions in both phases.Taken together,the present study found that both the IA and control groups showed inhibitory devaluation effects,and the degree of devaluation in the IA group was higher.The DLPFC and OFC were brain regions closely associated with the inhibitory devaluation effect,and there may be functional differences between the IA and control groups in these two brain regions.