Induced movement as nonveridical resolution of displacement ambiguity: Effect of enclosure and number of field elements

Four experiments on induced movement and induced stationariness are described. Experiments 1 and 2 showed that mere enclosure of a stationary spot in a moving frame does not necessarily result in induced movement. Nor does enclosure of a moving spot in a stationary frame necessarily result in perceived real movement of the spot. Duncker’s principles of enclosure is thus called into question. Two further experiments showed that both induced and perceived real movement of a spot are much more frequent when the frame is replaced by either two or more similar spots which enclose or flank the target spot. It can be concluded that the principle of enclosure obtains when the reference field consists of more than one element which move or remain stationary together. When such a field moves, it is the single, enclosed element which appears to move while the field itself appears stationary.