Possibilities of sensory leakage in the Ganzfeld experiments included the receivers hearing what was going on in the sender's room next door as the rooms were not soundproof and the sender's fingerprints to be visible on the target object for the receiver to see. Hyman reviewed the autoganzfeld experiments and discovered a pattern in the data that implied a visual cue may have taken place. Hyman wrote the autoganzfeld experiments were flawed because they did not preclude the possibility of sensory leakage.