Abstract

The success of a subject in identifying material presented in opaque envelopes was studied in relation to (1) the type of material used, and (2) the length of time between the presentation of the concealed object and the subject\'s response. The materials were numbers, drawings, letters, colored cards, and ESP cards, each with a 1/5 probability. The intervals varied from two seconds to more than a minute. A total of 1625 trials yielded 64 more correct identifications than mean chance expectation (CR = 3.97). The highest rate of success was obtained on colors and ESP symbols, and also a higher success rate was found with the longer delay intervals.