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This study examined whether a participant's level of interest in visual materials could be assessed by event-related potentials to auditory probe stimuli. Twelve young adults performed an auditory target detection task while viewing either interesting or less interesting (neutral) silent video clips. The auditory probe stimuli consisted of target (2000 Hz, p=0.15), standard (1800 Hz, p=0.70), and nontarget deviant (500 Hz, p=0.15) tones. Button press responses to target tones were required. Both target and deviant tones elicited a large P3 wave, the amplitude of which was smaller while participants were viewing interesting video clips than neutral video clips or simple still images (control condition). The amplitude reduction of the P3 to deviant tones was more prominent than that of the P3 to target tones. The difference between the neutral and control conditions was significant only for the deviant P3. The three-tone probe task using perceptually deviant, nontarget stimuli may be a useful objective method to assess how strongly a visual material attracts the viewer's attention.

The results, in conjunction with previous studies, emphasize the role of the spatial arrangement of genets on both the quantity and quality of offpsring, and suggest that an intermingled distribution of genets can reduce the mating costs of clonal growth and enhance overall fitness, particularly female fitness.

The authors examined altitudinal variations in the thermal responses of seed germination and seedling growth in Reynoutriajaponica ( = Polygonum cuspidatum) under controlled environmental conditions. Seed populations were collected from different altitudes on Mt Fuji in Japan. The mean seed weight of the upland populations (above 1500 m) was significantly (1.5-fold) heavier than that of the lowland populations (below 1400 m). Under the lowest temperature regime of 15//10 ~ (day/night) the upland populations showed a significantly higher percentage and speed of germination than the lowland populations; this was not significant under higher temperature regimes. These results indicate that the germination traits of the upland populations on Mt Fuji are favorable for colonization in their cold habitats (low temperature and short growing season). Growth and shoot development were compared between the seedlings grown from seeds collected at altitudes of 700 and 2420 m. The upland seedlings showed a significantly larger biomass and leaf area than the lowland seedlings at 15 ~ C, but there was no difference at 25 ~ C. The difference in biomass at 15 ~ was attributed to the difference in seed weight. The upland seedlings produced a significantly larger number of branches with smaller and more numerous leaves at both 15 ~ C and 25 ~ C. These developmental traits of the upland seedlings were considered to represent the adaptation of the life form to upland environments. It was concluded that the R. japonica populations along an altitudinal gradient on Mt Fuji can be dassified into two ecotypes, whose distribution border lies at an altitude of about 1400-1500 m. In this study, the seed weight and germination traits of two R. japonica seed populations collected in Chiba Prefecture were briefly compared with those of the lowland populations on Mt Fuji.