Many of our societal challenges from sustainability to democracy and community building will require our continued cooperation. With the prevalence of data rich digital technologies, this cooperation increasingly happens online where data-based feedback supports our decisions and people are often remote, asynchronous, and anonymous that has resulted in deindividuation and antinormative behavior. So how to encourage cooperation online where social cues are not readily available? Social data, information that users share about themselves via digital technologies, may offer opportunities for social feedback design that could afford perceptions of social awareness and unity that may support successful cooperation online. This body of work seeks to answer the normative question of how to design for cooperation in social data feedback charts online. I conducted mixed methods design research by combining theory-driven design with a series of controlled online experiments on Amazon Mechanical Turk to understand the perceptual and behavioral effects of manipulating two visual parameters of feedback charts: data point proximity and data point enclosure. To achieve this, Marlen first theorized about how visual unity in social data feedback might prime viewers with socially unifying perceptions, and then validated the theorizing with controlled perceptual and decision experiments. The results offer evidence for visually unifying cues being interpreted as social cues when applied to social data feedback charts. Two visual properties, namely data point proximity and enclosure trigger variable levels (small to large effect sizes) of perceivable social unity, but they play a secondary role in participants' decision to cooperate online in a social dilemma situation. This talk will discuss the implications of her findings for socio-visual perception via social data feedback charts, for designing in support of online cooperation online, and for future research involving social settings online.