A common cause for low satisfaction with group work in online courses is that teammates might be inactive and need to be prompted to take up work. Here, we specifically focus on the question of whether it is beneficial when the visualization of inactivity by the system is accompanied by negative consequences. In a field experiment in an online learning course we combined repeated questionnaires and behavioral data to examine whether vicarious punishment and transparency improve users' behavior (e.g. participation) and subjective perception (e.g. teamwork satisfaction). In a 2(x2) between-subjects design (N = 81, conducted over the course of 4 weeks), an abstract system signaled inactivity, whereby inactive teammates (confederates) were publicly addressed by name or not (vicarious punishment/no vicarious punishment condition). Additionally, to gain insights into how much needs to be known about the system's functioning, in the vicarious punishment condition participants were informed about the system's functionality in more/less detail, i.e. the system's transparency was varied (high/low transparency condition). Participation equality predicted teamwork satisfaction. Vicarious punishment led to more constructive prompts, but less observability of others, i.e. the ability to estimate others' contribution, which was even lower in the transparency condition. However, transparency revealed participants to be more afraid and a negative correlation with number of contributions emerged.