随着网络的普及，短视频社交平台迅速崛起，不仅吸引了网络主体人群——青年人，也吸引了越来越多的中老年人参与到平台。本研究以短视频平台头部平台抖音为例，着重于探究50-60岁的中老年的抖音用户使用抖音的情况如何，重点关注抖音的使用对他们的社交状况的影响。本研究以抖音使用情况为自变量（抖音使用功能、抖音使用强度），信息回音效应为因变量，探究抖音的使用会否致使目标用户出现信息回音效应。信息回音效应又叫信息茧房效应，指的是人们只关注自己感兴趣或自己选择的内容，而排斥其他内容，致使自己获得的信息内容不断窄化，像是被桎梏在一个像蚕茧一般的“茧房”之中一样，而信息回音必然导致的结果就是群体极化，可以说信息回音与群体极化二者相辅相成、密不可分。之后又引入另两个变量：主观幸福感和网络社群归属感，探究由抖音平台为目标用户带来的主观幸福感和网络社群归属感否对信息回音效应是否有预测作用，以及这二者是否在抖音的使用情况和信息回音效应两个变量之间起到中介作用。研究采用全国范围内随机抽样法，抽取样本共323份，经过剔除不符合年龄要求的样本，剩余299份，利用SPSS统计分析软件，对于数据进行分析，验证模型。

经数据分析发现，50-60岁中老年抖音用户使用抖音的总体情况十分积极，并且抖音的使用为他们带来了显著高于中值（3）的主观幸福感和网络社群归属感。进一步通过回归分析发现，抖音的使用情况、以及使用抖音带来的主观幸福感和网络社群归属感三者都对信息回音效应有显著的正向影响，表明使用抖音程度比较高以及由抖音平台带来比较高积极感受的中老年用户，会导致他们更容易基于抖音平台出现信息回音现象，导致信息窄化，出现群体极化情况。之后利用SPSS的插件PROCESS进行中介效应检测，结果显示多重中介效应模型中主观幸福感的中介效应显著，起到部分中介作用；网络社群归属感的中介效应不显著。而在二者的简单中介效应模型中显示二者的简单中介效应皆为显著，皆为部分中介作用。表明网络社群归属感在因变量和自变量之间起到一定的中介影响，但是当其与主观幸福感共同作为中介变量建模时，其中介效应影响效力明显不如主观幸福感强。

本研究的探明了50-60岁中老年群体使用抖音平台时的表现情况，以及使用抖音对他们感受和社交的影响。中老年群体一直是数字生活中的弱势群体，他们不擅长游走于各类数字产品却又容易掉入其中的陷阱，因此本研究将新兴的短视频平台与中老年人结合，验证了短视频平台为中老年群体带来了幸福感、归属感等稳定持久的积极感受，但伴随着积极感受的也有信息回音效应这一消极因素，这是一个群体性的危害。最后本研究根据研究结果为平台的发展和对老年人友好健康的设计提出了相应的建议，力求抓住中老年人的痛点和需求，也为后续相关研究提供思路。

With the spread of the Internet, the short video social platforms have risen increasingly. They have attracted not only the main group of Internet —— young people, but also great many middle-aged and elderly people. This study uses one of the biggest short video platform TikTok as an example, to attempt to explore the condition of quinquagenarians using TikTok and concentrate on how using TikTok interferes their social status. In this study, the independent variable is the condition of using TikTok, including the features and the strength of using. And the dependent variable is information echo effect. The main purpose is to test whether the target users will show information echo effect when using TikTok. The information echo effect is also called information cocoons effect, which means that people only care about the content and information of their interests or selections reject content of other aspects, resulting in information continuous narrowing, like fettering in a cocoon. And the information cocoons will definitely cause group polarization. This two complement each other and are interwoven. Then the study introduces two variables, subjective well-being and sense of Internet community, to explore whether the subjective well-being and the sense of Internet community belonging by using TikTok can effectively indicate information echo effect, and whether the two have mediation between independent variable and dependent variable. The study uses the method of random sampling which gathered 323 samples. And after cleaning up the unqualified data, the study finally remains 299 samples, which were analyzed by SPSS to verify the model.

After analyzing the data, the study has found that the condition of quinquagenarians using TikTok is quite positive. And using TikTok bring them the subjective well-being and the sense of Internet community which is significantly higher than middle value(3). Furthermore, through a regression analysis, the study has found that the condition of using TikTok, the subjective well-being and the sense of Internet community causing by TikTok are all have positive impact on information echo effect. It manifests that target users with high degree of using TikTok and high degree of the two senses, are easier to appear information echo effect, result in information narrowing and group polarization. Afterwards using the plugin PROSESS in SPSS to test mediation of the two variables. The result demonstrates that in multiple mediation effect model, the subjective well-being’s mediation is significant, and played a partial mediating role. But the sense of Internet community does not have significant mediating effect. And after making further efforts to test simple mediation effect, it shows that both of the two variables have significant mediation between the independent variable and the dependent variable, and are both partial mediation. It could be deduced that the sense of Internet community has relatively mediating effect, but its mediating effect is evidently weaker than the subjective well-being’s when in multiple mediation effect model.

The study demonstrated how the quinquagenarians uses the TikTok and how the TikTok influences their social status. Middle-aged and elderly people are always the disadvantaged groups among digital environment. They are not skilled in digital products but always easy to fall into traps. Thus this study associates the developing short video platform with quinquagenarians to verify that the short video platform bring quinquagenarians steady and positive feelings as subjective well-being and sense of Internet community. But accompany with positive feelings, comes the negative factor——the information echo effect. It is a harm to groups. Ultimately the study provides relative suggestions which is good for the development of platforms and well-being of the quinquagenarians according to research results, making an effort to grasp their pain-points and needs. It provides ideas to follow-up studies as well.