H. Mourier (1965) described a “novelty effect” in the response of houseflies, Musca domestica L., to a “new object” (usually a 15×15 cm square black tile) placed on the floor of their cage. On its first introduction into their familiar environment, the tile appeared highly attractive and received many visits. The number of visits thereafter decreased and approached a constant level after about 20 min. If the tile was then removed and replaced after an interval of less than 5 min there was no novelty receptivity, but this gradually returned as the time the tile was out of the cage was more and more extended. After 40–60 minutes the response was equal to the “new object” attractiveness. The flies did not seem to miss the tile when it was removed (Mourier, pers. comm., 1971).