Introduction: Out-of-hospital cardiac arrest (OHCA) is an unexpected event that frequently renders patients incapacitated therefore requiring a surrogate decision maker (SDM) to act as a proxy. When exercising judgement under uncertainty, people engage in one of two cognitive processing styles (i.e., dual processing): “fast” processing - automatic and intuitive or “slow” processing - deliberative and rational. Understanding which style(s) SDMs use in making decisions for post-arrest patients is critical to ensuring that (1) patients’ wishes are respected and (2) evidence-based neuro-prognostication is supported. Methods: We conducted a secondary analysis of semi-structured interviews with SDMs for OHCA patients. Potential subjects were contacted 30 days after discharge/death. The interviews were recorded and transcribed verbatim. Two investigators thematically coded the transcripts. We conducted secondary coding to specifically explore cognitive processing styles used by SDMs. Results: Over 5-months, 34 SDMS were approached and 12 SDMs agreed to be interviewed. SDMs were spouses/partners (5), adult children (3), parent (1) and siblings (3). Within this sample, 66.7% (8/12) of SDMs decided to withdraw life sustaining therapy or discontinue resuscitative efforts for the patient. Our secondary coding yielded variation in cognitive processing styles, with SDMs describing both fast and slow styles. SDMs who employed “fast” cognitive processing described (1) making their decision based on group consensus, (2) employing an affect heuristic (deciding based on “gut feeling” or temporary emotional state), (3) employing an availability heuristic (deciding based on examples of other patients or scenarios that immediately come to mind), and (4) deciding based on providers’ opinions without consulting other sources. SDMs who utilized “slow” cognitive processing described (1) focusing on the patient’s wishes when deciding and (2) gathering information to make an informed decision. Conclusions: SDMs utilized “fast” and “slow” cognitive processing approaches to decision making for OHCA patients. Future study should explore the relationship between SDMs’ cognitive processing styles and their decisions for post-arrest care.