Illusory changes of distinct speech upon repetition--the verbal transformation effect.

If a loop of tape plays a clearly pronounced word or phrase over and over, sudden shifts seem to occur in what is being said. This ‘verbal transformation effect’ continues at frequent intervals during continued stimulation, sometimes introducing a new form, sometimes returning to a form already reported. The illusion was found for all stimuli used: from a word with two speech sounds to complete sentences. Quantitative measures were obtained of the effect of stimulus complexity, loudness, masking noise, and repetition rate. Transitions frequently involved a very great degree of phonetic distortion and often exhibited semantic consistency.