The facilitating role of the facial expression of surprise in the discrimination of the facial expression of fear was analyzed. The sample consisted of 202 subjects that undertook a forced-choice test in which they had to decide as quickly as possible whether the facial expression displayed on-screen was one of fear, anger or happiness. Variations were made to the prime expression (neutral expression, or one of surprise); the target expression (facial expression of fear, anger or happiness), and the prime duration (50 ms, 150 ms or 250 ms). The results revealed shorter reaction times in the response to the expression of fear when the prime expression was one of surprise, with a prime duration of 50 ms (p = .009) and 150 ms (p = .001), compared to when the prime expression was a neutral one. By contrast, the reaction times were longer in the discrimination of an expression of fear when the prime expression was one of surprise with a prime duration of 250 ms (p < .0001), compared to when the prime expression was a neutral one. This pattern of results was obtained solely in the discrimination of the expression of fear. The discussion focuses on these findings and the possible functional continuity between surprise and fear.

Experiments were conducted to determine the effects of dry heat, direct flame, and straw burning on germination of several weed species from lowbush blueberry fields. Dry heat experiments were designed as factorial arrangements of temperature (100, 200, and 300 C in experiment 1 and room temperature, 100, 200, and 300 C in experiment 2) and exposure time (0, 5, 10, 20, 40, and 80 s in experiment 1 and 2, 5, 10, and 20 s in experiment 2) to determine the exposure time required to reduce germination for each temperature. Susceptibility to dry heat varied across species tested, but germination of spreading dogbane, meadow salsify, fireweed, and hair fescue seeds collected from lowbush blueberry fields in Nova Scotia, Canada generally declined exponentially as a function of duration of heat exposure at the temperatures tested. Germination decreased more rapidly at higher temperatures in all species, although the duration of heat exposure required to reduce germination by 50 and 90% varied across temperatures and species. Exposure of seeds to direct flame rapidly reduced germination, with less than 1 s of exposure required to reduce seed germination of witchgrass, spreading dogbane, and meadow salsify by > 90%. Straw burning did not consistently reduce germination of hair fescue or winter bentgrass, indicating that a surface burn occurring above weed seeds may not be consistently effective at reducing seed viability. These results provide important estimates of the temperature and exposure times required to reduce viability of weed seeds in lowbush blueberry fields and suggest that thermal technologies that expose weed seeds to direct flame will be the most consistent in reducing seed viability.