The Left Vision Advantage Of Visual Processin

Visual field advantage(VFA)refers to the uneven distribution of attention in different spatial locations with a certain bias.This phenomenon is called left visual field advantage(LVFA),which is usually manifested by a slight bias toward the left half of the visual field,resulting in a higher correct response rate to stimuli presented in the left visual field.In recent years,studies on left visual field advantage mainly used the rapid serial visual presentation paradigm(RSVP),in which subjects need identify two targets(T1 and T2)in a series of stimuli.The results of their studies showed that individuals recognized T2 in the left visual field significantly more correctly than T2 in the right visual field,thus finding that individuals had a significant left visual field advantage in the recognition of T2.Since insufficient cognitive resources might lead to visual field advantage,to exclude the effect of this factor,the investigators used the event-related potential(ERP)technique with standard stimuli.The results showed that the latency of P1 in the right hemisphere was significantly smaller than the latency of P1 in the left hemisphere.However,previous study using simple shape stimuli did not find a visual field advantage,which might be due to the task is simple.Therefore,based on previous study,the present study aimed to investigate the effect of sequence position on visual field advantage after increasing cognitive load and furture to study the neural mechanisms by which visual field advantage arises.To a certain extent,it can enrich the related studies on visual field advantage,while the study of the left and right hemisphere performance of visual field advantage using ERP technique can provide evidence to the debate between the left hemisphere load theory and the right hemisphere dominance theory.The specific experimental design is as follows.Experiment 1 was designed to investigate the effect of sequence position on visual field advantage.A 3(sequence location: T1,T2,T3)× 2(spatial location: left,right)within-subjects experimental design was used,and the dependent variable was correct response rate.In this experiment,colored geometric shapes were used as experimental materials,where the target stimulus was a red circle,using the method of hemifield tachistoscopy,designed to present the stimulus quickly.There were three sequence positions(T1,T2,T3)according to the temporal order of stimulus appearance,and the visual field had two spatial positions(left and right)according to the stimulus appearance.Subjects were required to respond with a keystroke to the presence or absence of the target stimulus in the sequence stimuli.The results showed that individuals responded significantly more correctly to T2 in the left visual field than to T2 in the right visual field,showing a left visual field advantage for T2,while the correct response rates for T1 and T3 did not differ significantly in the left and right visual fields.This suggested that cognitive load was an important influence on the emergence of visual field advantage.Since T2 processing was influenced by T1,to exclude this effect,Experiment 2 would investigate the standard stimuli in RSVP using the ERP technique to further examine the validity of the two hypotheses of left hemisphere load and right hemisphere dominance by controlling for the timing of cognitive load emergence in the two hemispheres.In addition,Lag and target location congruency were also important factors affecting the correct rate of T2 responses,so Experiment 2 would include them for further study to further investigate visual field advantage.Experiment 2 was designed to explore the neural mechanisms of left visual field advantage using ERP techniques.A 3(presentation: left visual field presented first,left and right visual fields presented simultaneously,right visual field presented first)× 2(Lag: 1,4)× 2(target position: left,right)× 2(whether T1 and T2 positions are consistent: consistent,inconsistent)within-subject experimental design was used,with the behavioral dependent variable indicator being the correct response rate and the ERP dependent variable indicators being the amplitude and latency of P1.This experiment used a dual RSVP paradigm,sequential stimuli containing numbers and letters as experimental material,T1 as blue letters and T2 as black numbers.Stimuli presented rapidly,requiring subjects to press the corresponding buttons for T1 and T2 at the end of each trial.The results of the behavioral data revealed that the left visual field advantage of T2 was found in all conditions,except for the T1 position which coincided with the T2 position and the Lag1 condition.ERP results revealed no significant difference in P1 amplitude between the left and right hemispheres in the left and right visual field simultaneous presentation condition,indicating that the left hemisphere loading theory was not valid;in addition,the latency of P1 in the right hemisphere in the left visual field first presentation condition was smaller than that in the left and right visual field In addition,the latency of P1 in the right hemisphere under the simultaneous presentation condition was smaller than that of P1 in the left hemisphere under the simultaneous presentation condition,and the latency of P1 in the right hemisphere under the simultaneous presentation condition was smaller than that of P1 in the left hemisphere.This indicated that the visual field advantage of the individual was due to the dominance of the right hemisphere.In summary,the following conclusions were obtained from this study:(1)Task load affected left visual field advantage.A lower degree of cognitive load caused left visual field advantage to disappear,and an appropriate increase in cognitive load results in left visual field advantage.(2)Visual field advantage differed at different sequence positions.Individuals had a left visual field advantage for T2 recognition.(3)The main reason for the emergence of left visual field advantage was the dominance of the right hemisphere.