Reading the documentation of invoked API functions in program comprehension

Comprehending an unfamiliar code fragment requires an awareness of explicit usage directives that may be present in the documentation of some invoked functions. Since it is not practical for developers to thoroughly investigate every call, directives may be missed and errors may occur. We previously reported on a tool called eMoose, which highlights calls to methods with associated directives, and on a controlled comparative lab study in which eMoose users were more successful at fixing bugs in given code fragments. In this paper we attempt to shed light on the factors behind these differences with a detailed analysis of videos from the study. We argue that information foraging theory may explain the subjects´ reading choices and the impact of our tool. We also suggest ways to structure documentation to increase the prospects of knowledge acquisition.