Phi Phenomenon Research Articles

Reading disability, perceptual continuity, and phi thresholds.

Birch and Kephart hold contradictory views regarding the intactness of visual form perception in disabled readers. Although Birch's techniques demonstrate form discrimination, they do not necessarily measure discrimination by means of form. To provide a critical test of Kephart's assumption regarding a qualitatively inferior perceptual process in disabled readers, a test based upon the phi phenomenon was employed. One study involved 20 disabled readers and 20 normal achievers, a second, 12 disabled readers and 12 normal achievers. The results support Birch's claim regarding the intactness of visual form discrimination in disabled readers.

Imperception of phi: some further determinants.

An apparent movement situation was presented to control and neurotic groups. Perception of the phi phenomenon was postulated to be associated with neurotic mechanisms and with behaviour operationally defined as conflict and ambiguity avoidance, and was considered to express a generalized perceptual attitude of the individual. Neurotics were found to have lower mean movement intervals than control subjects, and to find it more difficult to perceive the phi phenomenon. The latter tendency was particularly marked in obsessionals and hysterics. Perception of phi was found to be associated with age of subject, becoming more difficult with greater age. Imperception of phi among the neurotic sample remained greater than in the control group after partialling out age. The findings are interpreted as supporting two hypotheses derived from a set of postulates linking a perceptual attitude of ambiguity avoidance with ego defences.

Studies on the clinical investigation of retinal correspondence.

The number of recent publications on the clinical investigation of the status of the sensorial retinal relationship of patients with strabismus is an indication of the interest which this subject arouses among ophthalmologists. We have undertaken, on the suggestion of Dr. Hermann M. Burian, to evaluate some of the tests which have lately been reported and to elucidate their physiologic basis. In the present paper we shall report our results obtained with the prism rack test of Rønne and Rindziunski and on tests utilizing the phi phenomenon. <h3>PRISM RACK TEST</h3> Our study was primarily stimulated by the publication of an article by Rønne and Rindziunski,¹in which they theorize on the pathogenesis of anomalous retinal correspondence and utilize for the first time a test which they call the prism rack test. In this test the eyes of the patient are individually exposed to a vertical bar of light. The

Central and peripheral factors in the phi phenomenon.

Central and peripheral factors in the phi phenomenon.

Differentiation of Phi Phenomenon and Parallax : The Use of Phi Phenomenon in Determination of Retinal Correspondence

Differentiation of Phi Phenomenon and Parallax : The Use of Phi Phenomenon in Determination of Retinal Correspondence

Visual Apparent Movement in the Absence of Neural Interaction

The literature concerned with the problem of visual apparent movement has been reviewed by Neff.' His paper describes Wertheimer's classical experiments defining the phi phenomenon,2 outlines later research, and considers the theoretical formulations which have grown up about the problem of apparent movement. Several hypotheses have been offered to explain visual apparent movement. Of all such hypotheses, those advanced by the Gestalt psychologists have been perhaps the best known and the most controversial.3 In general, the Gestalt theories contend that the experience of visual apparent movement is a direct one, correlated with appropriate neural stimulation. Not only is the initial stimulus presumed to activate one tract of the visual neural system, and the second stimulus to activate another; but by physiological interaction the two serially stimulated tracts are supposed to create between them a field of excitation whose path corresponds to the spatial path of the observed movement. It is this field which is held responsible for the experience of movement. Wertheimer's original formulation assigned the locus of interaction to the higher neural centers; later formulations have been much less specific.4

PHI PHENOMENON AND ANOMALOUS PROJECTION

If the eyes are exposed to an external visual stimulus, then this is quickly extinguished and the eyes are exposed to a similar stimulus from a different place, the two stimuli may be perceived as a single stimulus which has moved across the intervening space. Such apparent motion was first investigated by Exner1in 1875 and given the designation by Wertheimer2in 1912. Since the advent of advertising signs which utilize this phenomenon, it has become generally familiar. It has been extensively investigated,3and much is now known as to the conditions which are most apt to elicit it, including the time and space intervals. Experimental conditions have been produced under which the observer cannot distinguish between the apparent movement in the Phi phenomenon and actual movement when the conditions for one are substituted for those of the other. It is known that the phenomenon

An Experimental Study of Visual Movement and the Phi Phenomenon

An Experimental Study of Visual Movement and the Phi Phenomenon