Public mobile phone use is often viewed negatively, although the reason for these negative perceptions is unclear. The current study examined perceptions of public mobile phone users in a 2 X 2 factorial design. Participants viewed a staged video of a public conversation that was either face-to-face or over a mobile and later rated their perception of the conversation and target speaker. Two variables were manipulated: whether participants could hear both sides or only one side of the conversation, and whether the conversation took place over a mobile phone or was face-to-face. The results indicated that the one side mobile phone conversation was more noticeable, intrusive, and annoying to overhear compared to the two-sided mobile speaker phone conversation and one side inaudible face-to-face conversation. Additionally, participants indicated that the target speaker in the one side mobile phone conversation was liked less than the target speaker in the mobile speaker phone condition and was perceived as more extroverted when participants could only hear one side of the conversation. The findings from this study are discussed in relation to previous data as to why public mobile phone conversations are generally perceived negatively by others. / Department of Psychological Science