Pupillary responses (PR) change differently for different types of stimuli. This study aims to check whether observers’ PR can recognise real and posed smiles from a set of smile images and videos. We showed the smile images and smile videos stimuli to observers, and recorded their pupillary responses considering four different situations, namely paired videos, paired images, single videos, and single images. When the same smiler was viewed by observers in both real and posed smile forms, we refer them as “paired”; otherwise we use the term “single”. The primary analysis on pupil data revealed that the differences of pupillary response between real and posed smiles are more significant in case of paired videos compared to others. This result is found from timeline analysis, KS-test, and ANOVA test. Overall, our model can recognise real and posed smiles from observers’ pupillary responses instead of smilers’ responses. Our research will be applicable in affective computing and computerhuman interaction for measuring emotional authenticity.