The Influence Of Horizontal And Vertical Asymmetry On The Object Effect: The Moderating Effect Of Task Difficulty

Object-based attention is one of the main modes of selective attention,it refers to the recognition of two or more features within in the same object is faster and more accurate than the recognition of two or more features within different objects.The most popular paradigm on object-based attention is two-rectangle cueing paradigm.In addition to the object,performance across the visual field is not always homogeneous.Research found that better performance on the horizontal than vertical meridian,which is the horizontal-vertical anisotropy.Thus,using the two-rectangle paradigm,the object-based attention of horizontal object is consistent with the horizontal-vertical anisotropy while the object-based attention of vertical object is opposite to the horizontal-vertical anisotropy,the object-based attention effect of different orientation objects should be different.However,previous studies on whether the object orientation can affect the sign of object-based selection effects have not been given a consistent conclusion.When the object orientation is taken as an independent variable,some studies have found the effect of object orientation on object-based attention,while others have not found it.Compared with previous studies,we found that the key factor leading to differences in experimental results may be task difficulty.Therefore,Experiment 1 and 2 used three different levels of difficulty to explore whether the task difficulty played a decisive role in the effect of horizontal-vertical anisotropy on object-based attention.Experiment 3 in order to eliminate the pollution of the object effect by horizontal-vertical anisotropy and then get a purer object effect.This study contains three experiments,used two-rectangle cuing paradigm and its modifications.Experiment 1 used task difficulty(detection task,simple discrimination task,and difficult discrimination task),object orientation(horizontal,vertical),and cue validity(valid,invalid-same object,invalid-different object)as the within-factors,to explore the effect of object orientation on the object-based attention under different difficulty task.The results show that the object-based cueing effect were found at both task,and the object-based selection effect was same in the detection task,however,strongly modulated by rectangle orientation,being larger for horizontal than vertical rectangles in the simple discrimination task.That is to say horizontal-vertical anisotropy can't affect the sign of object-based selection effects in the detection task,can affect in the simple discrimination task.In order to further verify the important role of task difficulty in the impact of horizontal-vertical anisotropy on the object-based cueing effect.Experiment 2 we limited the time that targets appeared on the screen to only 60ms,after which they were swiftly masked.This manipulation increased task difficulty,experiment 2 explores the effect of object orientation on the object-based attention under difficult discrimination task.The results showed that the object-based cueing effect when objects are horizontal,and a significant reversal of the object-based cueing effect when objects are vertical.We used task difficulty(detection task,simple discrimination task,and difficult discrimination task),object orientation(horizontal,vertical)as between-factors,object-based cueing effect as the dependent variable.Compared the influence of object orientation on object-based attention under different task difficulty.The results show that with the increase of the task difficulty,the amount of object-based attention effect of horizontal objects increases,while that of vertical objects decreases.In order to eliminate the pollution of the object effect by horizontal-vertical anisotropy and then get a purer object effect.Experiment 3 used simple discrimination task,and clockwise or counterclockwise rotate rectangular to 45°,making the cue and the target position is no longer horizontal and vertical,this operation effectively eliminates horizontal-vertical anisotropy.The results showed the effect of object orientation on the object-based attention disappears,and the tilted 45° rectangle can get a purer object effect.Based on the results of the first,second and third experiments and the related discussions,we can draw the following conclusions:1.horizontal-vertical anisotropy can't affect the sign of object-based selection effects in the detection task,it can affect in the simple discrimination task and difficult discrimination task.2.The effect of horizontal-vertical anisotropy on the object-based attention effect is modulated by the task difficulty,the harder the task is,the greater impact of the horizontal-vertical anisotropy on the object-based attention effect.3.Using the tilt 45° rectangle to exclude the horizontal-vertical anisotropy,even if under the simple discrimination task,object orientation can't affect the object-based selection effects,also can obtain a purer object-based attention.