Untersuchungen zur Lokalisierung von Wahrnehmungsprozessen: Figurale Nachwirkungen bei binokularen Wettstreit-Bedingungen

Figural aftereffects were measured under binocular-rivalry conditions, the suppressed part of the binocular-rivalry situation being used as an inspection figure. The results show that figural aftereffects are reduced in a partly suppressed configuration and disappear completely when the inspection figure is fully suppressed. This indicates that the figural aftereffect process is localized at a higher level in the visual system than area 17.

Figural Aftereffects in Vision as a Function of Surround

Sagara and Oyama (1957) summarized a number of Japanese studies in which luminance, contrast and illuminance were varied during investigations of figural aftereffects (FAEs) of the type reported by Gibson (1933) and Koehler and Wallach (1944). With regard to luminance the magnitude of the FAEs increased with the increase in the luminance of the inspection figure when a luminous stimulus in a dark room was used. Recently Day and Strelow (1970) reported that the aftereffect of seen movement was absent or markedly reduced when the surround was dark or fearureless. The stationary FAE, therefore, appeared to be present in the absence of surround while the motion FAE was not. The present investigation was designed to see if presence or absence of surround per se had any influence on the stationary FAE.

Tactile and Kinesthetic Influences on Visual Figural Aftereffects

12 Ss were presented with a bent line I (inspection) figure followed by a straight line T (test) figure under four different conditions in order to produce a FAE of a bent line. In the visual condition S saw the I figure and then the T figure. In the tactile condition S held a curved bar and viewed the I figure simultaneously. The two kinesthetic conditions required S feel a straight or curved bar and view the I figure simultaneously. In both the kinesthetic and tactile curved-bar conditions Ss showed a strong tendency to perceive the visual T figure as curved. In the other conditions Ss perceived the T figure as bent (the usual effect produced by this combination of I and T figures). The results demonstrate the influence of kinesthetic and tactile stimulation on visual FAE.

Effects of Varying the Apparent Tilt of the Inspection Figure on a Kinaesthetic After-Effect

Three experiments were conducted to determine whether kinaesthetic after-effects, measured by settings of a bar to the horizontal, are controlled by the apparent or the physical tilt of the bar during inspection. Two arrangements were used to induce a discrepancy between apparent and physical tilt. Data obtained with one arrangement did not permit a proper test of the issue. With the other arrangement either distorted or undistorted visual information about tilt was present during kinaesthetic inspection. It was found that post-inspection settings were displaced from pre-inspection settings in the direction of the tilt of the inspection figure when there was no discrepancy between information presented by the two modalities. When there was a discrepancy, the displacements attributable to apparent tilt were in the direction opposite to the apparent tilt of the inspection figure. The former effects dissipated rapidly after inspection; the latter did not. It is suggested that after-effects obtained following an inspection period during which there is no discrepancy between physical and apparent tilt are controlled by the physical tilt of the inspection figure and that apparent tilt, when it is an effective variable, operates by modifying the judgemental frame of reference.

Drugs and Personality

Figural after-effects are the observable results of a hypothetical process of satiation or inhibition which accompanies and follows the passage of neural currents consequent upon stimulation. Most of the work in this field has been on figural after-effects affecting contours. In this work an inspection figure is fixated for a fairly lengthy period of time; this is then withdrawn and two test figures are substituted. One of these test figures falls within the same area as the inspection figure while the other is well removed from this area. Differences in size between the two figures which are objectively equal are usually observed and are supposed to be a consequence of satiation set up by the inspection figure (McEwen, 1958).