Social tagging as a new approach for metadata creation has emerged to support browsing, searching, sharing on social network sites. Tag clouds are visual displays of social tags. In this paper we reported a user study on tag cloud perception. The goal of our evaluation is to investigate the effect of some of the different properties that can be utilized in presenting tags e. g. tag font size, tag location. Both behavior data and eye tracking data demonstrated a significant effect of font size, but effect of tag locations was mixed. Big tags were recalled better than medium and small font tags regardless of their locations in a tag cloud. Tags in the middle circle of a tag cloud received longer eye duration than outer circle, but were not recalled better.