Influence Of Olfactory Stimulation On Divergent Thinking

Probably the oldest and mysterious sensory system in the nature,olfaction plays an important role in human life.Many studies have explored the effects of olfactory stimulation on mental process(such as attention,memory,emotion,etc.),but few studies have focused on the role of olfactory stimulation in influencing divergent thinking.This study aims to investigate the effects of different olfactory stimulation on divergent thinking and explore how olfactory stimulation affect divergent thinking by means of electroencephalogram(EEG)-based event-related synchronization/ desynchronization(ERS/ERD).Experiment 1 aims to classify the influence of olfactory stimulation on divergent thinking from the standpoint of behavior measurement.Specifically,whether olfactory stimulation can affect divergent thinking,whether there are differences in the effects of different olfactory stimulation,and the possible mechanisms underlying the effect.Within-subjects design was used to measure participants' emotions,divergent thinking(realistic presented problem,RPP),executive functions,and associative abilities in three experimental conditions: peppermint,lavender and air.The results showed that the peppermint odor can promote the performance of divergent thinking,while changing individual's emotional valence,arousal and cognitive shifting ability.However,emotional valence,arousal and cognitive shifting do not act as mediators between peppermint and divergent thinking.These findings indicated that olfactory stimulation can affect divergent thinking and different olfactory stimulation have different effects.Among them,peppermint can improve the performance of divergent thinking tasks and peppermint maybe not affect divergent thinking based upon emotional pleasure,arousal and cognitive shifting.The aim of experiment 2 is to investigate the influence of olfactory stimulation on divergent thinking from the standpoint of neural activity,that is,whether divergent thinking in different olfactory stimulation show different neural activity patterns and whether differences between neural activities reflect different performance of divergent thinking.All subjects were repeated measured divergent thinking(alternative uses task,AUT)in three experimental conditions: peppermint,lavender and air.While completing the AUT,using EEG to record neural activity.The behavior results showed that the main effect of olfactory stimulation on divergent thinking was not significant.The EEG results revealed that when completing the divergent thinking task,the main effect of olfactory stimulation on the ERS of the lower alpha band(8-10 Hz)in the prefrontal and parietal regions was significant.And the ERS in peppermint and lavender conditions were both significantly higher than the ERS in air condition.In addition,there is a significant positive correlation between the ERS in prefrontal lobe and the fluency and flexibility of divergent thinking in peppermint condition.In divergent thinking,the lower alpha ERS in frontal region characterizes top-down cognitive control,the ERS in parietal lobe characterizes the recombination and integration of semantically distant information,which indicated peppermint and lavender may enhance the top-down control and the spreading activation in semantic networks to affect the divergent thinking.This study confirms the effect of olfactory stimulation on divergent thinking based upon behavior performance,and uses EEG-based neural synchronization to reveal the difference of neural activities accompanying divergent thinking in different olfactory stimulation.The above findings have paved the way for further exploration of the brain mechanism that olfactory stimulation affects divergent thinking,and provide new evidence for supporting the influence of olfaction on advanced cognitive activities.