Negativity bias is the tendency to pay more attention and give more weight to negative information than positive information. This study explored how negativity bias affects information search, processing, and sensemaking when reading news articles on controversial topics. We conducted an eye‐tracking experiment with 43 participants who sought and read positive and negative articles about the three‐child policy debate. We measured their eye movements, cognitive load, attitude change, and sensemaking outcomes. We found that: (1) negativity bias occurs in both information search and information processing, and the outcomes of sensemaking also tend to show negative changes; (2) reading positive articles increase cognitive load more than reading negative articles; (3) gender and prior attitude have an influence on negativity bias; (4) people use different cognitive strategies when making sense of positive and negative information. This paper contributes to a better understanding of negativity bias in information seeking, processing, and sensemaking, which can help design news systems that adapt to readers' needs, and suggests people view information objectively.