The Object-based Attention Without Awareness

Research on awareness was one of the 125 scientific frontier issues that Science put forward at the 125th anniversary of its founding.At present,there are two different viewpoints on the relationship between visual attention and visual awareness.It is generally acknowledged that attention and awareness share an intimate relationship.When an observer pays attention to an object,he or she becomes conscious of its various attributes;when attention shifts away,the object seems to fade from awareness.Due to this tight relationship,many researchers posit that these two processes are inextricably entangled,if not identical.On the other hand,more and more researchers posit that attention and awareness are distinct phenomena,with distinct functions and neuronal mechanisms.However,the relationship between attention and awareness has not yet formed a consistent viewpoint.Therefore,to explore the relationship between attention and awareness has become an important issue in psychology and neuroscience.Because attention is a relatively broad notion,it can be understood in several different ways,such as space-based attention,object-based attention and so on.Therefore,some researchers have suggested that the relationship of each type of attention to awareness should be studied separately,if we want to really understand the relationship between attention and awareness.At present,the study on the relationship between space-based attention and visual awareness has basically formed a consistent conclusion,that is.space-based attention and visual awareness can be separated from each other in function.Furthermore,this conclusion has been confirmed in the study of blindsight patient and normal participants.So far,however,there is little study on the relationship between object-based attention and visual awareness.And only a few studies have failed to reach a consistent conclusion.Compared to space-based attention,the neural mechanism of object-based attention is more complex and more relevant to that of visual perception.Therefore,it is clear that the relationship between object-based attention and visual awareness can further promote the development of the relationship between visual attention and visual awareness.As mentioned before,the main purpose of this dissertation was to investigate the object-based attentional effect without awareness.It consisted of two studies,which systematically investigates the object-based attentional effect without awareness from two aspects,namely,target without awareness(study 1)and object without awareness(study 2).There were two behavioral experiments and one ERP experiment in study 1.The purpose of this study was to examine the object-based attentional effect without awareness of the target.Experiment 1 used the double-rectangle cueing paradigm to investigation this problem.The result showed that the object-based attentional effect appeared in the absence of awareness of the target condition.Furthermore,compared to the invalid-different condition,participants had shorter RTs in the invalid-same condition.Experiment 2 also used the double-rectangle cueing paradigm,but unlike experiment 1,the probability of the target appearing at the four ends of the rectangles was the same.In other words,eliminating the validity of the cue,the probability of the target appearing in the cued object and the uncued object was equal.The result showed that eliminating the prediction of cue could only affect the space-based attentional effect in the absence of awareness of the target condition but had no significant effect on the object-based attentional effect in the absence of awareness of the target condition,which suggested that the object-based attentional effect without awareness of the target was not affected by the validity of the cue.Experiment 3 used event-related potential technique to examine the object-based attentional effect without awareness of the target and its neural mechanism.The result showed that compared to the target in the invalid-differnet condition,when the target in the invalid-same condition could elicit a larger posterior N1,which suggested that the target in the invalid-same condition could evoke a greater degree of activation.This result demonstrated that the object-based attentional effect could occur in the absence of awareness of the target condition.Combined with the results of the above three experiments,study 1 mainly found that the object-based attentional effect counld occur in the absence of awareness of the target condition.Study 2 also had two behavioral experiments and one ERP experiment.This study mainly examined whether the object-based attention could be guided by an invisible object.Based on the experimental paradigm of Zhang and Fang(2012),experiment 4 explored whether the invisible intact rectangular object could affect the deployment of attention.The result showed that the object-based attentional effect appeared under the condition of the invisible intact rectangular object,which suggested that the object-based attention could be guided by the invisible intact rectangular object.Experiment 5 used the same experimental paradigm as experiment 4 used and explored whether the invisible perceptual object could guide attention.To our knowledge,there were no studies to explore this problem.The result showed that the object-based attentional effect also appeared under the condition of the invisible perceptual object,which suggested that the participants could form an intact object representation through unconscious processing,so as to produce a stable object-based attentional effect.Experiment 6 used event-related potential technique to examine the object-based attentional effect without awareness of the objects and its neural mechanism.The result showed that compared to the target in the invalid-differnet condition,when the target in the invalid-same condition could elicit a larger posterior N1,which further suggested that the object-based attentional effect could still occur with invisible objects.In addition,this result also demonstrated that the psychological mechanisms that give rise to the object-based attentional effect were related to attentional spreading.Combined with the results of three experiments,this study comfirmed that the object-based attentional effect could still occur under the condition of the objects without awareness from the perspective of invisible objects.In summary,the results of the present study were as follows:(1)the object-based attentional effect could appear under the condition of the target without awareness.(2)the validity of the cue could only affect the space-based attention without awareness but had no significant effect on the object-based attention without awareness.(3)the invisible intact rectangular objects could guide the deployment of attention,resulting in the object-based attentional effect.(4)the object-based attentional effect could occur with the invisible perceptual rectangular objects.(5)it was associated with a greater degree of activation induced at about 200 ms regardless of the object-based attentional effect without awareness of the target or without awareness of the objetcs.(6)the object-based attentional effect could occur without awareness,which suggested that the object-based attention and visual awareness could be separated from each other in function.(7)the psychological mechanisms that give rise to the object-based attentional effect were associated with attentional spreading.In sum,from the present study,we can conclude that the object-based attentional effect can occur without awareness,and that the object-based attention and visual awareness are distinct functions.