The Effect Of Reward On Selective Attention And Its Underlying Mechanism

In our daily life,individuals have to receive a large amount of sensory information from the environment all the time.Because of the limited cognitive resources,individuals will preferentially select part of information for further cognitive processing and ignore other redundant information.In recent years,researchers have paid more and more attention to the effects of rewards,especially monetary rewards,on attentional processing.The related research can be divided into two fields.On one hand,some studies explored the effects of reward cues on attentional control.It has been confirmed that positive reward cues can facilitate attentional processing,featured by the faster response speed and higher accuracy.But there is no unified conclusion about the effect of negative reward cues on attention control.On the other hand,some research has explored the effect of reward associated stimuli,features,and locations on attentional selection.When reward is bonded with the target stimulus,feature or location,it can promote individuals' attentional response.In contrast,when reward is associated with the task-irrelevant stimulus,feature or location,it will interfere with one's attentional processing.Previous research has deepened our understanding of the mechanisms of attention.It is worth mentioning that these studies have mainly focused on the effect of the presence or absence of reward cues or reward associations on attentional processing.However,individuals may have to choose between multiple value features when making attentional choices in real life.By now,few studies have explored people's attentional selection strategies when facing multiple reward features at the same time.In this research,we conducted two studies to investigate: 1.People's attentional selection mechanisms in the face of two reward-associated features at the same time;2.Whether positive and negative reward cues and associations influence attentional selection equally.Study 1 consisted of three experiments,which systematically explored whether the mechanism of attention selection in the face of two reward-linked features conforms to the relative value model or the absolute value model.Experiment 1 employed a two phase training-test paradigm basing on reward learning.In the training phase,participants learned the association between two different colors(red and green)and high or low rewards by performing an attentional search task.In the test phase,all the subjects were asked to perform an attentional search task with no reward.We manipulated the value contrast between the target and one critical distractor during the test phase.The results of experiment 1 showed that when the value of the target was much higher than that of the critical distractor,subjects' reaction time was significantly shorter than that of all the conditions that the relative value of the targets was small.In the contrary,when the relative value of the target was far less than the value of the distractor,the reaction time of the subjects was significantly longer than that of other conditions with high relative value of the target.Experiment 2 adopted the same paradigm as experiment 1,but we manipulated the value difference between the target and the distractor in two groups.The results of experiment 2 showed that when the relative value of the target was the lowest,the reaction time of the subjects was significantly longer than that of the condition that the relative value of the target was higher.Besides,the accuracy rate was lower than that of the condition that the relative value of the target was higher.Experiment 3 also used the same paradigm as experiment 1,except the balanced physical salience of the target stimuli against the distractor stimuli.The results of experiment 3 also showed that when the relative value of the target was low,subjects' reaction time was significantly longer than that of other conditions with high relative value of target.Overall,study 1 used three experiments to show that after the reward learning,subjects were more likely to allocate attentional resources basing on the relative value model when facing multiple value features.In other words,individuals will give priority to features and stimuli which have higher relative value.In addition,we found that the difficulty of value comparison between two reward features and the presentation of other value options in the context may affect individuals' preference when making attentional selection between two reward features.In study 2,we explored whether positive and negative reward cues and reward associations influence individuals' attention selection based on the same mechanism.We aimed to test whether the mechanism of attention selection follows the principle of utility maximization.Study 2 consisted of two experiments.In experiment 4,we explored the influence of positive and negative reward cues on individuals' attention control at the same time.Experiment 4 used an attentional search task,in which subjects could get positive reward,negative reward or no reward respectively in different blocks.The results of experiment 4 showed that the reaction time of subjects under positive and negative reward cue condition was significantly shorter than that under neutral condition,and the accuracy rate of subjects under positive and negative reward condition was significantly higher than that under neutral condition.There was no significant difference between positive and negative reward conditions.Experiment 5 also adopted the training-test paradigm based on reward learning.The training task was designed to make participants associate colors with different rewards.In the test phase,we employed a dot-probe task to explore the influence of the appearance of positive and negative reward-associated features on individuals' attention selection.The results of experiment 5 showed that there was no significant difference between positive and negative reward conditions,and the accuracy rate under inconsistent condition was higher than that under consistent condition.This can be explained as the effect of inhibition of return.Overall,study 2 showed that both positive and negative reward cues could facilitate subjects' attentional search,and there was no significant difference between these two conditions.Thus,it seems that the mechanism underlying reward based attentional selection conforms to the principle of utility maximization.In summary,this research found that individuals' attentional selection is more likely to give priority to the relative value of stimuli rather than the absolute value of it.More specifically,when faced with multiple value options at the same time,individuals tend to choose the stimulus or feature with the greatest relative value.It follows that the value of rewards is largely relative,which subject to value comparisons.However,this research only focused on the behavioral mechanisms.In the future,we need to provide neural evidence to test whether the mechanisms of reward-related attentional selection conform to the relative value model.In addition,future studies also need to consider the emotional component of reward when exploring how reward influence attentional selection.