A saccadic suppression explanation of the Pulfrich phenomenon

Harker, George S.

doi:10.3758/bf03208781

Cited by 20 publications

(10 citation statements)

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“…In conclusion, these data do not support Harker's (1967) saccadic suppression explanation of the Pulfrich stereophenomenon. If differential suppression of input from each retina is involved in the effect, some other gating mechanism must be postulated to account for it.…”

Section: Resultscontrasting

confidence: 52%

“…Harker (1967) rediscovered this effect and suggested that a similar mechanism was responsible for the Pulfrich phenomenon, the gating being brought about by assymetries in the duration of suppression of visual input occurring during saccadic movement of the eyes. Harker argued that as the period of saccadic suppression is a function of the intensity of target illumination, the presence of a filter before one eye provides the necessary conditions for differential saccadic suppression, resulting in a distortion in the seen path of a moving object.…”

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confidence: 99%

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Eye movement and the Pulfrich effect

Kirkwood

Ellis

Nicol

1969

Perception & Psychophysics

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Under certain conditions a simple harmonic pendulum viewed binocularly appears to swing in an elliptical path rather than to and fro in a plane. This effect occurs when a filter is placed over one eye (the Pulfrich effect) or when an episcotister is used to occlude the view to each eye alternately (the Mach-Dvorak effect). The explanation put forward for the former effect by Pulfrich (1922), later expanded by Lit (1949) and Alpern (1968), is in terms of the theory of corresponding retinal points and variations in the latency of information transmission along the visual pathways. Placing a filter before one eye reduces retinal illuminance and increases visual latency. Thus, simultaneous excitation of the corresponding retinal points of unequally illuminated retinas results in simultaneous convergence at some central analyzer of impulses from disparate retinal areas, and this disparity is interpreted as a depth displacement of a moving object.The Mach-Dvorak effect (Dvorak, 1872) is readily accounted for in terms of retinal disparity directly induced by alternately gating the input to each eye. Harker (1967) rediscovered this effect and suggested that a similar mechanism was responsible for the Pulfrich phenomenon, the gating being brought about by assymetries in the duration of suppression of visual input occurring during saccadic movement of the eyes. Harker argued that as the period of saccadic suppression is a function of the intensity of target illumination, the presence of a filter before one eye provides the necessary conditions for differential saccadic suppression, resulting in a distortion in the seen path of a moving object.The present paper reports an empirical test of Harker's explanation by monitoring eye movements while the S views a moving pendulum bob with and without a filter before one eye. The effect of instructions for "natural" viewing, fixation upon the pendulum bob, and fixation upon a stationary point while observing the moving pendulum bob is also described. METHOD SubjectsFour young adult Ss without readily detectable visual or neurological abnormalities served. Two were initially naive regarding the Pulfrich phenomenon but their results did not differ materially from those obtained from the other Ss. ApparatusEye movement potentials (EOG) were monitored via Beckman Ag/Ag CI surface electrodes used in conjunction with Offner paste. These potentials were amplified by a de-coupled Offner RS dynograph, the output of which was also displayed on a Tektronix 502A dual-beam CRO and photographed on 35-mm film.The S was seated in an electrically shielded darkroom with his movements restricted by a chin rest and head holder. A frame held a sliding glass plate in front of his eyes, arranged so that when the slide was moved from side to side the S looked' through plain glass with both eyes or through plain glass with the left eye while an Ilford neutral density filter (25% transmittance) covered the right eye. This was done to minimize changes in eye position compensating for the purely refractive e...

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Section: Resultscontrasting

confidence: 52%

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confidence: 99%

Eye movement and the Pulfrich effect

Kirkwood

Ellis

Nicol

1969

Perception & Psychophysics

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“…Such an offset would signal termination of the advance of retinal stimulation in the direction of object motion (Harker, 1967). In addition, the pattern of the response, particularly the insensitivity to direction of interocular average luminance difference, identifies relative stimulus intensity or its counterpart, relative excitation, as the critical variable.…”

Section: Discussionmentioning

confidence: 99%

“…It was as though the dichoptic views were stereoscopically combined as disparate pairs (Lit, 1978). Harker (1967) used an episcotister that provided relatively long and overlapping views to the two eyes. He observed that the presence of a period of common view as part of the dichoptic sequence did not disrupt the stereoscopic depth displacement although there could be no geometric disparity during the binocular interval.…”

Section: University Of Louisville Louisville Kentuckymentioning

confidence: 99%

Interocular intermittence, retinal illuminance, and apparent depth displacement of a moving object

Harker

Jones

1985

Perception & Psychophysics

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“…The neutral point, point of no perceived depth displacement, associated with t,3th eyes viewinti together for a time (simultaneous neut:'al point) shou'd mark the reductio,: to zero of the effective disparity between the fusion referent of the experimental and index exoosures. The relative depth perceived as this point is approached is such that (right eye before the left eye) rotation of a pendulum would be counterclock and vice versa (1,3,6,7).…”

Section: Introductionmentioning

confidence: 99%