The Eye-Movement Research About Face In Crowd Effect:The Dispute Of Target Orienting,Target Processing And Distracter Processing

When participants are asked to search an array of several emotional faces, search efficiency of one emotion face (e.g., angry face) would like to be faster than that of another emotion face (e.g., happy face), this kind of phenomenon is named as the search asymmetry of emotional faces or face in crowd effect. Hansen and Hansen (1988) did some researches on this topic pioneerly and found angry-face superiority effect which means the search efficiency of angry faces was faster than that of happy faces. Because of one specificity of emotional facial expressions which include plenty of biological and physical information that would help us to improve the comprehension of the mechanism of information processing, following the investigation of Hansen and Hansen (1988), more and more investigators are doing researches about search asymmetry of emotional faces. They found that the search asymmetry of emotional faces had two kind of categories:one was the negative-face superiority effect, like the angry-face superiority effect; the another one was positive-face superiority effect, like the happy-face superiority. Since then, many investigators have done some investigations on the mechanism of search asymmetry and proposed two theories:(1) Target orienting, which proposes the main reason of search asymmetry is because compared with one emotional face, the another one emotional face would like to be captured by our attention easily, so the search efficiency of the latter emotional face would be higher than the former; (2) Distractor processing, which proposes that the difference of processing time of difference distractors is the main reason of search asymmetry, specifically, the processing time of one emotional face is more or lesser than that of the other one emotional face. No matter what kind of search asymmetry of emotional faces, they are all supported by many researches. However, based on the previous researches, the present research found many deficiencies:firstly, from the perspective of experimental design, the researches of search asymmetry of seminal faces would like to use visual search paradigm which only has one search target among many distractors and visual search researches reveal that before ending the search behavior, participants prefer to scan the search target more than once, so during the process, the differences of search targets may affect the search process; based on this, we thought there was also the phenomenon of repeated scanning in the array of faces, so whether the target emotional faces would affect the search asymmetry should be investigated; in addition, in the aspect of data processing, the investigators prefer to use the orientation of first saccade to evaluate the guidance of search targets, however, during the search, at the beginning of search behavior, we have captured the locations of target faces, but before moving our eye balls, the other factors in our visual field guide our saccades to other places, as the results the effect of target orienting is delayed. So we proposed that the interval between the beginning of this trial and the start time of first fixation which located the search target, name as eye-movement latency, should be used to evaluate the effect of target orienting; thirdly, the investigators would like to investigate the two theories separately and did not investigate the interaction of them; finally, the former investigations like to control the identity of faces to make sure the faces in one search array are coming from one person, however, the real situation is that the faces are different people, so the ecological validity of the results of the previous researches are limited.In the present study, two experiments were carried out on the limitation above mentioned, combining visual search paradigm and eye-movement technology. In Experiment 1, we kept the identical consistency of faces in one trial and asked the participants to make an judgement about whether the emotions in the search array were same or not, by collecting the eye-movement data, e.g., the average number and time of fixations locating on the target faces and distractor faces; the duration of eye-movement latency and decision phase, and the average number and time of fixations locating on the distractor faces in the eye-movement latency and decision phase, to investigate the effects of target guidance, distractor processing and target processing, and the interactions of target guidance and distractor processing, distractor processing and target processing. On the basis of Experiment 1, Experiment 2 adopted same method, but changing the identities of faces in one trial, so we could improve the ecological validity of the results of Experiment 1.Under the condition of inconsisteney of search array, une behavior resuiis reveaied that the main effect of target emotions was significant, the search performance (accuracy rate and reaction time) and search efficiency of happy faces was higher than that of angry faces, that was happy-face superiority; besides, the interactions between target emotions and distractor emotions were also significant, that was to say, search target and distractors all affected search asymmetry of emotional faces. Moreover, the eye-movement data found the main effects of target emotions on all eye-movement data were all significant, which mean target would affect the whole searching process; and in the aspect of the duration of eye-movement latency and decision phase, and the fixations locating on distractors of two phase, the interactions between target emotions and distractor emotions were also significant; and in the perspective of the fixations locating on targets, the interactions were also significant. Under the condition of consistency of search array, the average fixation time would be different among different emotional faces, specifically, the processing time of angry face was the longest, the neutral face was the shortest. Based on these results, we made the following conclusions:Regardless of whether the identities in the search array were same or not, (1) under the condition of this face images, the search asymmetry of emotional faces was happy-face superiority; (2) target orienting, distractor processing and target processing all affected the search asymmetry of emotional faces; (3) distractors would have influence on the guidance of search targets; (4) the effects of distractor processing on the search asymmetry of emotional faces would be affected by search targets; (5) search targets and distractors affected the decision phase together.