A Comparative Study On Visual Change Detection Of Deaf And Hearing People

Vision is the most important channel for the input of external stimulus, because 80% of information input is through vision. It is even more critical for Deaf people whose auditory input channel has been deprived. For Deaf people's visual cognition abilities, Deficiency Hypothesis and Compensation Hypothesis are contradicting with each other, and supported by empirical evidences respectively. The literature shows that, the visual cognition of Deaf people is different from the hearing. However, limited empirical studies have focused on the different characteristics of visual change detection between Deaf and hearing people. Moreover, the distinctions between the abilities of change detection of different visual stimulus materials with different relevance to the experience of subjects have not been distinguished yet. Thus, this study shed lights on the different characteristics of visual change detection of Deaf and hearing people. A variety of visual presentation materials, including simple geometric figures and human faces, and different change-detection-related experiment paradigms are employed in this study to compare the visual change detection characteristics between Deaf and hearing people.There are four parts in this paper. Firstly, literatures on Deaf people's visual cognition have been reviewed. The focus and design of this study is proposed after summarizing the perspectives advocated by past researches, and the possible gaps in this realm that need further investigations.In the second part, results from four experiments in this study were reported.The first experiment used simple geometric figures to look into the visual change detection process of both Deaf and hearing people, and the one-shot change detection paradigm is employed. The result shows that the performance of hearing people decreases with the elevation of task difficulty, however this is not the case for Deaf people whose performance is not subject to difficulty changes and always significantly lower than hearing people. In addition, for Deaf people, the endogenous visual attention resources will be prioritized to visual stimuli that are vertically aligned in vision field.The second experiment requires both hearing and Deaf subjects to complete a face recognition task. The result shows that Deaf people outperform hearing people, in which Deaf people performed better than hearing people when they recall the details of eyes, but not for mouths.The third experiment involves a parallel comparison task for faces. The result shows that Deaf people performed better than hearing people, and their advantage in this task is more evident than the face recognition task. Similarly, Deaf people performed better in the tasks involving difference detection of details for eyes, but not for mouths.The fourth experiment employs the flicker paradigm, and subjects are asked to complete the change detection tasks using simple geometric figures, faces that are upright, and faces that are reversed. The result shows that Deaf people has poorer performance than hearing people in change detection task with simple geometric figures. However, they performed better with both upright and reversed faces. When compared with the data in experiment one, it shows that Deaf people tend to distribute more visual cognition resources to the peripheral vision field when the cognitive resource is not in extreme constraints.All the results driven from this study show that the life experience of Deaf people have footprints on their visual cognitive ability and process. On the one hand, the auditory deprivation leads to their visual cognitive resources being overly occupied, and thus not easily being summoned when necessary for a certain visual cognitive task, on the other hand, their sign language experience lead to their enhanced face cognitive ability, and their tendency to distribute cognitive resources to the visual stimuli that are aligned vertically in their vision fields. A hypothesis that embraces a systematic point of view, and is independent of the Deficiency Hypothesis and Compensation Hypothesis has been proposed. It advocates that the different characteristics of visual change cognition of Deaf and hearing people are derived from the adaptability of the cognitive system, rather than the over-simplified dichotomy of the deficiency or compensatory mechanisms. This study can be regarded as a meaningful supplement for the literatures of the visual cognition studies, and also providing meaningful applications in special education of Deaf students.