We found that the detection threshold changed in a trial period of a few seconds in a simple detection task of a single pulse. The threshold increased at the earlier onset time in a trial but became constant in a lower level at the later period in the trial. The possibility of cross-modal attentional shift between vision and audition or tactility was tested. The change of detection threshold disappeared with a stationary edge in the peripheral visual field. It is suggested that this change of the detection threshold is caused by the stationary retinal image with the Ganzfeld stimulation and the eye movement.

Beutter et al. (Vision Research, 36, 3061–3075, 1996) pointed out that both the ratio of elongated aperture and the spatial frequency bias the perceived direction of motion of the plaids that are composed of sine-wave gratings. They criticized the IOC and other models for spatial integration of motion signals. In this paper,experiments were designed such that a drifting plaid of grating bars formed the stimulus; it was windowed by a rectangular frame with the same luminance as that of the background. The subjects were asked to continuously observe this plaid pattern. The results revealed that the duration for perceiving coherent motion of the plaids is affected by both the ratio of the rectangular windows and the spatial frequency; this is in agreement with the results in Beutter et al. (1996). Further, our results suggested that the stimulus in this experiment is also under the barber pole effect caused by the elongation of the aperture. It should be noted that for the stimulus used in this experiment, the plaid is perceived as a single net-like structure in coherent motion similar to other plaid patterns. However, in component motion, each grating is perceived to move parallel to the longer frame of the rectangular aperture and not perpendicular to its orientation. Hence, the two grating bars move in directions opposite to each other in a different depth plane. In order to explain this observation, our analysis was focused on the width of the grating bars and relatability (Kellman & Shipley: Cognitive Psychology, 23, 141–221, 1991). It was suggested that the phenomenon is affected by the conditional decision of the terminators (extrinsic or intrinsic) with relatability.