In this paper, we report three user experiments that investigate in how far the perception of a bar in a bar chart changes based on the height of its neighboring bars. We hypothesized that the perception of the very same bar, for instance, might differ when it is surrounded by the top highest vs. the top lowest bars. Our results show that such neighborhood effects exist: a target bar surrounded by high neighbor bars, is perceived to be lower as the same bar surrounded with low neighbors. Yet, the effect size of this neighborhood effect is small compared to other data-inherent effects: the judgment accuracy largely depends on the target bar rank, number of data items, and other data characteristics of the dataset. Based on the findings, we discuss design implications for perceptually optimizing bar charts.

Timely access to professional medical advice is crucial for patient health outcomes. Traditional offline, one-on-one patient-provider interactions are time consuming and costly. As a result, online "Ask the doctor" (AtD) services have become increasingly popular, where patients and caregivers can obtain advice from medical professionals at a lower information and transaction cost. In this paper, we present an empirical study of Fenda, an innovative AtD platform recently introduced in China where patients and caregivers can consult a wide variety of healthcare professionals for a small fee. Using qualitative research methods, we analyzed how patients and caregivers interact with medical professionals on this platform, focusing on the nature of the questions asked and user strategies to optimize the usage of the platform. We further derived implications for designing better online AtD services connecting patients and caregivers to medical professionals.