The work provides insights into the motivations and behavioral patterns associated with shoulder surfing behavior on smartphones in public spaces from the perspective of observers using eye-tracking technology and standardized questionnaires. The underlying psychological and social factors are explored by covertly observing participants in a waiting room scenario with a decoy that creates a realistic shoulder surfing opportunity. The participants' glances at a nearby smartphone were analyzed, and it was found that boredom and curiosity were the most common motives for shoulder surfing. The results showed a significant correlation between the participants' personality traits, such as openness and conscientiousness, and their propensity for this behavior. The study also highlights the discrepancy between self-assessment and actual behavior observed through eye-tracking. This study contributes to the understanding of the challenges of digital privacy shows an innovative experimental approach for further research. Keywords: shoulder surfing, eye-tracking, smartphone privacy, behavioral analysis