When people judge whether others are telling the truth, they act differently if they are working alone or in a group. The current experiment explored this finding. Participants (working alone or in pairs) provided either a binary truth/lie decision, or a binary decision and a set of reasons chosen from a list, or an open ended discussion/explanation. Being alone or in a pair had no significant effect on accuracy, but confidence was higher in pairs. A truth bias was found in the single condition but was eliminated for pairs when they specified a reason or had a discussion. Accuracy was highest when stating a reason chosen from a list, while confidence increased with the amount of information provided. These findings improve our understanding of the effect of pair decision making, illustrating how varying levels of information can have different effect on decision making and deception detection.