The IDAC (Information, Decision, and Action in Crew context) model is developed to probabilistically predict the responses of the nuclear power plant control room operating crew in accident conditions to be used for human reliability analysis in the context of probabilistic risk assessment. The operator response spectrum includes cognitive, psychological, and physical activities. This paper discusses the IDAC set of performance influencing factors, providing their definitions and causal organization in the form of a modular influence diagram. The supporting evidence for the selection and organization of the influence paths based on psychological literature, observations, and various human reliability analysis methodologies is also provided.