Findings on how humans detect cultural differences in cultural pictogram interpretations are reported. An answer web survey was conducted in the United and Japan to collect U.S.-Japan pictogram. Thirty U.S.-Japan pictogram interpretations used as stimuli for human cultural difference study. Three U.S. subjects and three Japanese participated in the study to assess the degree of differences in the thirty pictogram interpretations in the questionnaire. Post-questionnaire interviews conducted to elucidate the reasons behind the human difference detection. The following factors were when humans detect cultural differences in cultural pictogram interpretations: (i) similar or interpretations in the two countries, (ii) or ranking of the interpretations, (iii) or variance of semantics within one country's, (iv) presence of proper nouns (e.g. country ), and (v) positive or negative connotation in the interpretations.