Following the preceding report, fixation points by eye movements were measured for moving TV Picturer(with Sound/without sound), continuous still Pictures and various Japanese texts. From these measured data, some statistical properties for these pictures were obtained from flequency distributions - fixations times, distances between points and moving velocities-, average values and loci of fixation points.

View full abstract

The relation between the r-g opponent-color transformation and the cone mechanisms was analyzed by determining the shift of unique yellow locus under chromatic adaptation and the t.v.i curves of the M and L cone mechanisms. The shift of unique yellow locus could not be accounted for by the model of Buchsbaum & Gottschalk (1983) and von Kries coefficient law. It is suggested that multiplicative adaptation mechanisms at post receptor process may contribute to the adaptation behavior of the r-g opponent-color system.

View full abstract

Threshold for the just-perceptible neon color bleeding and the strength of the effect were determined as a function of the wavelength of the stimulus pattern. The spectral sensitivity function showed the characteristic of an achromatic mechanism at the threshold, while it showed the opponent nature at the suprathreshold. It is suggested that luminance cues of some kind are necessary for color to elicit a sharp image.

View full abstract

A motion aftereffect induced by a stimulus changing its size produces a perception of motion-in-depth. Similarly, a relative motion of opposite edges presenting subparts of such a stimulus also produces the aftereffect of motion-in-depth. In this study, we examined the spatial and temporal properties of the relative motion for the aftereffect of motion-in-depth. In experiment 1, we used two vertical lines moving away from each other. After adaptation, two stationary test lines were first perceived to be approaching each other (2D-MAE), and subsequently perceived to be moving away from the observer (3D-MAE). This aftereffect gradually decreased as the distance between the two lines increased and then disappeared at about 3 deg/arc apart. In experiment 2, we examined the effect of presenting the two adaptation lines sequentially. The 2D-MAE was induced, but the 3D-MAE could not be found. These results suggest that the aftereffect of motion-in-depth has properties of a spatial and temporal limit.

View full abstract

Lightness match and brightness match in color mondrian images simulated by CRT were studied under the spatial illumination gradients. D65 illuminant was used in our experiment, and the strength of illumination changes at the center of the stimulus like a step edge. The plane-like and the sphere-like mondrian images were used. The result of lightness match shows that human can estimate the lightness (reflectance) in color stimulus in spite of abrupt illumination change. Furthermore, empirical formulas for lightness and brightness matches were proposed.

View full abstract

This paper presents a model of preattentive texture boundary detection. This model is constracted based on physiological and psychological data. The model consists of three stages. In the first stage Gabor filter decomposition provides representations of an image : orientation selectivity, spatial frequency. Following this, five modules for feature extraction are introduced : brightness contrast, scale contrast, orientation contrast, hyper-orientation contrast and end-of-line density contranst. Each module outputs high value where its feature's value change quickly among neighbouring area. In the final stage these information are compared and intergrared into the final output. The model has been tested with several classical stimuli from psychophysical literature. According to the results of experiments, this model has an ability to detect texture boundaries where we perceive ones in preattentive process.

View full abstract