LONG-TERM OBSERVATION OF THE AUTOKINETIC ILLUSION: FREQUENCY AND DIRECTION OF MOVEMENT,

This study was designed to test the following hypotheses a reports of autokinetic movement increase with increasing exposure time b reports of movement in the vertical plane occur with greater frequency than reports of movement in the horizontal plane. Forty subjects, who were told that they were radar watchkeepers, observed a pin point of light in a dark room for 30 min. and indicated the direction of apparent movement. The results obtained supported both hypotheses. The increase in reports of movement is accounted for in terms of increased suggestibility due to the effects of sensory deprivation. A possible explanation for the greater frequency of reports of vertical movement is discussed in terms of Kummapas theory of the releva5ce of the horizontallyextended oval shape of the visual field for the horizontal-veritcal illusion. Author