The Steady-state Visual Evoked Potential In Chinese Characters And Face Individuation Recognition

Both word and face individualized recognition were critical issues in the object recognition.Face and Chinese character,the typical perceptual expertise objects for Chinese,are featured by specific brain area and N170 component.Previous evidence of word and face individualized recognition are mainly derived from behavior,fMRI(functional Magnetic Resonance Imaging)and ERP(Event-related Potential)studies.Recently,a new method characterized by objective,efficient and sensitive was proposed to explore the individualized recognition of word and face,i.e.,SSVEP signal(SteadyState Visual Evoked Potential)which is elicited by FPVS(fast periodic visual stimulation)paradigm.Previous studies demonstrated that SSVEP signal is a sensitive EEG indicator of word and face recognition,but the features of SSVEP signal for individualized recognition of Chinese characters.Moreover,Caucasian was largely investigated by SSVEP in face recognition,whose face processing ability was different from that of the Eastern.Investigation in Eastern individuals would further reveal whether SSVEP signal is race-specific or race-general in face processing.Therefore,using the signal elicited by FPVS paradigm in Chinese face and Chinese character recognition,our study aimed to figure out whether this indicator works for Chinese character and face recognition in Chinese subject.Our study also aimed to further explore the difference between the two perceptual expertise objects.A series of experiments were designed to study face and Chinese character recognition,and the relationship between the neural SSVEP signal and behavior effect for perceptual expertise.Experiment 1 used SSVEP signal evoked by FPVS paradigm(stimuli were presented with a frequency of 6Hz)to study face and Chinese characters recognition and the relationship between its neural signal and composite effect.Experiment 2A explored the Chinese characters with fine-grained difference(a chimeric character formed by the left or right halves of a symmetrical character and its mirror one)processing and its neural signal correlates with behavioral left-bias effect.Experiment 2B and 2C investigated the individualized recognition of fine-grained faces and its neural signal correlation with left-side bias.The results showed as followed:(1)Face and Chinese character individualized response at 1.2 Hz and its harmonics is significantly larger than noise,indicating that it is a reliable indicator of complex objects individualized recognition and the indicator is race-general.(2)The SNR(Signal to Noise Ratio)of face was significantly lower than that of Chinese character and house in FPVS paradigm,suggesting the response is face-specific,not expertise-specific.(3)In the Chinese character with fine-grained difference,the results showed that in the original-right condition,there existed a significant response at 1.2 Hz and its harmonics in the left hemisphere when upright Chinese characters presented.When presenting inverted,the significant response existed both in left and right hemisphere.Besides,in the original-left condition,there was also a significant response in the left hemisphere.The results suggested that recognition for the right chimeric characters(original-right condition)is better than for the left chimeric characters.The results also showed response at 1.2 Hz and its harmonics is a reliable indicator of left-bias effect.(4)In the face with fine-grained difference,the results indicated a significant frequency of oddball face in the left hemisphere,suggesting a reliable indicator of chimeric face recognition.Moreover,with increasing face presenting duration from 167 ms to 250 ms,the frequency of oddball face in the right hemisphere become reliable and stable.(5)Correlation analysis showed that the SNR for the fundamental frequency in the left hemisphere positively correlated with behavioral composite effects in the both upright face and Chinese character.Besides,in the left hemisphere,the SNR for the fundamental frequency in the right chimeric character positively correlated with left biased effect,whereas the SNR of right chimeric fact negatively correlated with left left biased effect.These results indicated that the perceptual expertise processing may correlate with the fundamental frequency of the left hemisphere and the perceptual expertise processing has its hemispheric dominance.