The pursuit of Leonardo's constraint

Leonardo da Vinci (1452-1519) identified two stimulus situations that cannot be painted faithfully on a canvas: (a) when two objects are located in the same direction with respect to the painter's head, and (b) when parts of a surface are visible to one eye, but occluded from the other eye. He analysed these situations in terms of rays being emitted from the two eyes and, aside from the origin of the rays, the projective geometry he used was correct. His analyses showed that what can be seen from two vantage points cannot be represented on a canvas, because a 'correct' painting must be created from a single 'station point'. He was struck by the consequence of this fact that the depth seen on a canvas cannot match that of viewing the scene with two eyes. Subsequent visual scientists focused on Leonardo's observation about the lack of vivid depth in a picture. We argue that a complete understanding of what we see in the two stimulus situations requires consideration of visual direction in addition to visual depth. More specifically, we argue that the visual directions of the two objects, (a) above, and the visual direction of the monocular areas, (b) above, are dependent upon the constraint that two opaque objects cannot be represented in the same direction. Demonstrations that readers can perform, and that support this argument, are provided on the Perception website at http://www.perceptionweb.com/perc0102/ono.html.     

Low income, unemployment, and suicide mortality rates for middle-age persons in Japan

The relationships between age-specific suicide mortality rates and social life factors for all 47 Japanese prefectures in 1980, 1985, and 1990 were assessed by multiple regression analysis after factor analysis on 20 social life indicators. During this period, Japan experienced a secondary oil crisis in 1980-1983 and a bubble economy in 1986-1990. It was concluded that (1) low income was the major determinant which positively affected suicide mortality rate in middle-aged men during a previous 20-yr. period (1970-1990), (2) urbanization was negatively associated with male suicide mortality rates in most of the age classes in the 1980s, (3) unemployment was one of the major determinants of increased suicide mortality rate in middle-age men in the 1980s, and (4) unemployment was the major factor which was inversely associated with suicide mortality rate for elderly women from 1980 to 1990 in Japan.     

A new variant of the Ouchi illusion reveals Fourier-component-based processing

We report that anomalous motion illusion in a new variant of the Ouchi figure is well predicted by the strength of its Fourier fundamentals and harmonics. The original Ouchi figure consists of a rectangular checkerboard pattern surrounded by an orthogonal rectangular checkerboard pattern, in which illusory relative motion between the two regions is perceived. Although this illusion has been explained in terms of biases in integrating one-dimensional motion signals to determine the two-dimensional motion direction, the physiological mechanism has not been clarified. With our new stimuli, which consisted of thin lines instead of rectangles, we found that the perceived illusion is drastically reduced when the position of each line element is randomly shifted. This is not predicted by simple models of local motion integration along the visible edges. We demonstrate that the relative amplitude of the relevant Fourier fundamentals and harmonics leads to a quantitative prediction. Our analysis was successfully applied to other variants of the Ouchi figure (Khang and Essock 1997 Perception 26 585-597), closely predicting the reported rating. The results indicate that the underlying physiological mechanism is sensitive to the Fourier components of the stimuli rather than the visible edges.     

Effects of excitotoxic brain lesions on taste-mediated odor learning in the rat

The association learning between taste and odor is important in ingestive behavior. For a better understanding of this learning, we have developed a convenient and useful paradigm to assess the taste-mediated odor learning. In the training session, Wistar male rats drank water from two bottles in their home cages and from eight small glass dishes. In the learning session they were exposed in their home cages and also in a circular open-field apparatus to 0.005 M Na-saccharin and 0.02 M quinine hydrochloride which contained either banana or almond odors. One learning trial consisted of this pair of exposures. The preceding behavioral experiment has shown that these two odors are not aversive and are differentially perceived by rats. In the test session, the animals were put in the open-field apparatus equipped with eight dishes: four contained water with banana, and another four, with almond. Normal control rats preferred to drink water with the odor previously associated with saccharin. Stronger and more persistent preference was attained after two or three learning trials. To elucidate the brain sites responsible for this taste-mediated odor learning, the same procedure was assessed on brain-lesioned rats. Rats with lesions in the amygdala showed rapid extinction of preference to the saccharin-associated odor, whereas control rats did not. However, rats with lesions in the insular cortex showed retention of learning similar to that of the control rats. Rats with lesions in the sulcal prefrontal or cingulate cortices showed moderate disruptive effects on preference to the saccharin-associated odor. In conclusion, the odor learning established in our experimental paradigm is based on the association between the quality of odor and hedonics of taste. The amygdala may play a role in the formation, at least in the retention process, of this taste-odor association learning.     

Effects of self-efficacy on adjustment to college

This study examined the effects of self-efficacy on adjustment to college among 1385 Japanese college students. The College Adjustment Self-Efficacy Scale (CASES) was constructed in order to evaluate the degree of confidence in the skills necessary for college adjustment. Three subscales were identified in the CASES: judgmental ability based on objective information, self-controlled persistence of activity, and self-adjustment in human relations. There were slight gender differences in the first and the third subscales. The CASES subscale scores were compared between well and poorly adjusted students in each college major. Differences in the score patterns of well adjusted students were compared across 13 college majors. The implications for academic career counseling are discussed.     

Robust Improvements on Reasoning Performance Following Discussion in Japan

Group discussion significantly improves performance on intellective problems. However, most experiments have been conducted in Western cultures. Cross‐cultural psychology suggests that members of Eastern cultures might be less likely to benefit from group discussion. One experiment in Japan suggested that this was not the case, but this experiment suffered from some limitations. To address these limitations, Japanese participants were asked to solve an intellective task four times: individually (pre‐test), in small discussion groups (test), individually again (transfer task, post‐test), and individually after a delay (delayed post‐test). The results revealed a robust improvement during group discussion. Groups in which at least one member had found the correct answer individually agreed on it during the discussion. Moreover, and in contrast with results obtained in Western cultures, most groups with no such member also found the correct answer. The gains obtained during discussion were maintained in the transfer tasks. This result provides further evidence that the improvement of reasoning performance in group discussion is a universal phenomenon, and provides support for the practice of collaborative learning in Japan.     

Multiple EMG activity and intracortical inhibition and facilitation during a fine finger movement under pressure

The 1st purpose of this study was to examine multiple electromyography (EMG) during voluntary hand movements. A secondary purpose was to investigate possible effects of pressure on intracortical inhibition (ICI) and intracortical facilitation (ICF) functions of the motor cortex, using paired-pulse transcranial magnetic stimulation. Twelve participants traced a 15-cm diameter target circle using a small laser pointer attached to the right index finger. After 5 acquisition trials, they performed 3 nonpressure trials followed by 3 pressure trials. The results showed that pressure had effects not only on agonist EMG activity but also on multiple muscles, such as synergist. In addition, a decrease in ICI and an increase in ICF were both observed under pressure for muscles other than the agonist.     

Limited capacity for contour curvature in iconic memory

We measured the difference threshold for contour curvature in iconic memory by using the cued discrimination method. The study stimulus consisting of 2 to 6 curved contours was briefly presented in the fovea, followed by two lines as cues. Subjects discriminated the curvature of two cued curves. The cue delays were 0 msec. and 300 msec. in Exps. 1 and 2, respectively, and 50 msec. before the study offset in Exp. 3. Analysis of data from Exps. 1 and 2 showed that the Weber fraction rose monotonically with the increase in set size. Clear set-size effects indicate that iconic memory has a limited capacity. Moreover, clear set-size effect in Exp. 3 indicates that perception itself has a limited capacity. Larger set-size effects in Exp. 1 than in Exp. 3 suggest that iconic memory after perceptual process has limited capacity. These properties of iconic memory at threshold level are contradictory to the traditional view that iconic memory has a high capacity both at suprathreshold and categorical levels.