In psychophysical experiments, subjects reported the two intervals of the three-dot stimulus to appear different in length in the presence of flanking stripes. The inside flanking stripes caused underestimation of the interval length, while the outside ones, conversely, induced overestimation. To establish the perceived length equality, the subjects changed the test interval length disabling the physical matching. The length matching error varied with the height of the stripes: it augmented asymptotically approaching the maximum value, 6-12% of the reference interval length. When the empty gaps were formed within the central part of the stripes, the error decreased monotonously with increase of the gap size. The experimental findings show the presence of a certain positional averaging within the excitation areas, which have the Gaussian profiles. The results go in parallel with predictions of the weighted averaging model (Bulatov, Bertulis, 2004, Informatica, p.1-12; Bulatov, Bertulis, 2005, Acta Neurobiologiae Experimentalis, p.265-269:)the excitation pattern of the focal stimulus is averaged with the excitation pattern of the contextual objects flanking the focal stimulus. In our experiments, positional averaging caused a shift of the perceived position of the end-points of the stimulus toward the position of appropriate flanking stripes.