家庭和同伴是影响儿童及青少年发展重要的微观系统。作为对应的两种人际关系，亲子关系和同伴关系往往会相互联系，共同影响个体的内外化问题。而在其中亲子依恋作为人际关系的基础，一直被广为讨论。但已有研究缺少对亲子依恋和同伴关系对儿童和青少年的内外化问题的整体性探讨。本研究将聚焦儿童中期和青春期中期两个发展阶段，整合亲子依恋和同伴关系来探讨两者对于抑郁和孤独感的影响。

研究一首先探讨亲子依恋对同伴关系的影响，比较亲子依恋的安全性、焦虑性和回避性对群体水平和双向水平的同伴关系的影响模式的差异。结果发现，在儿童中期，依恋安全性和依恋焦虑性显著正向预测友谊支持，依恋安全性显著负向预测友谊冲突，依恋焦虑性显著正向预测友谊冲突；在青春期中期，依恋安全性显著正向预测友谊支持，依恋焦虑性显著正向预测友谊冲突，依恋焦虑性显著正向预测受欢迎。

研究二采用结构方程模型的方法，来考察同伴关系对抑郁和孤独感的影响，并进一步采用潜剖面分析来明确同伴关系模式对抑郁和孤独感的影响。结果表明，在儿童中期，双向水平的同伴关系对于抑郁和孤独感的影响大于群体水平的同伴关系；在青春期中期，双向水平的同伴关系、群体水平的同伴关系对于抑郁和孤独感的影响可能相同。儿童中期和青春期中期潜剖面结果存在一定的差异。

基于以上研究，研究三讨论亲子依恋是否会通过影响群体水平的同伴关系和双向水平的同伴关系，进而影响抑郁和孤独感。结果发现，在儿童中期，依恋的安全性和焦虑性可以通过增加友谊支持来减少抑郁和孤独感，也可以通过影响友谊冲突来影响孤独感；而在青春期中期，依恋安全性可以通过增加友谊支持来减少抑郁和孤独感，依恋焦虑性也可以通过影响友谊冲突来影响孤独感。

综上，本研究发现亲子依恋和同伴关系都对儿童及青少年的抑郁和孤独感起着重要作用，并且亲子依恋会通过影响双向水平的同伴关系进而影响抑郁和孤独感。本研究明确了亲子依恋特性对同伴关系的影响，探讨了同伴关系模式及其对抑郁和孤独感的影响，并明确了亲子依恋如何通过同伴关系影响儿童及青少年的抑郁和孤独感表现。

Family and peer are crucial microsystems that have an impact on children's and adolescents’ development. As two corresponding interpersonal relationships, parent-child relationship and peer relationship are frequently linked and have an impact on internalizing symptoms and externalizing symptoms. Among them, parent-child attachment has been widely discussed as the foundation of interpersonal relationships. Studies to date, however, have not examined the impact of parent-child attachment and peer relationships on children's and adolescents’ internalizing symptoms and externalizing symptoms holistically. This study will integrate parent-child attachment and peer relationships, focusing on two developmental stages: mid-childhood and mid-adolescence, to examine the effects of both on depression and loneliness.

Study 1 first explored the effects of parent-child attachment on peer relationships, comparing differences effects of secure, anxious, and avoidant parent-child attachment on peer relationships at group-level and at dyadic-level. Results found that in mid-childhood, attachment security and attachment anxiety significantly positively predicted friend support, attachment security significantly negatively predicted friend conflict, attachment anxiety significantly positively predicted friend conflict; and in mid-adolescence, attachment security significantly positively predicted friend support, attachment anxiety significantly positively predicted friend conflict, and attachment anxiety significantly positively predicted popularity.

In Study 2, structural equation modeling was employed to examine the effects of peer relationships on depression and loneliness.  Additionally, the effects of peer relationship patterns on depression and loneliness were clarified through the use of latent profile analysis. The findings imply that, in mid-childhood, dyadic-level peer relationships have a greater effect on depression and loneliness than group-level peer relationships; in mid-adolescence, dyadic-level and group-level peer relationships may have an equal effect on depression and loneliness. The outcomes of the latent profiles between mid-childhood and mid-adolescence varied in certain ways.

Based on the above research, Study 3 discussed whether parent-child attachment influences peer relationships at group-level and dyadic-level, which in turn affects depression and loneliness. The results found that in mid-childhood, attachment security and anxiety can reduce depression and loneliness by increasing friend support, and can also affect loneliness by influencing friend conflict, while in mid-adolescence, attachment security can reduce depression and loneliness by increasing friend support, and attachment anxiety can also affect loneliness by influencing friend conflict.

 In conclusion, this research indicates that parent-child attachment and peer relationships are significant factors in depression and loneliness in children and adolescents, and that parent-child attachment affects depression and loneliness by influencing dyadic-level of peer relationships. This study clarifies the effects of parent-child attachment on peer relationships, sheds light on peer relationship patterns and their impact on depression and loneliness, and clarifies how peer relationship mediated the effect of parent-child attachment on depression and loneliness in children and adolescents.