Averaged evoked responses to clicks were elicited from 20 normal-hearing subjects between the ages of 16 and 41. Two thousand clicks were presented to the right ear at the rate of 10 per sec at 60, 30, 10, 5, 0, −5, and −10 dB SL. Sensation levels were varied randomly. In each series two control conditions without stimulation were randomly interspersed. Electroencephalic potentials were recorded from an electrode on the vertex of the skull referred to the left earlobe. The response pattern was relatively consistent with a vertex-negative peak (N a ) at about 20–24 msec, and a vertex-positive peak (P a ) at about 31–35 msec. Another vertex-negative peak (N b ) at about 46–50 msec was seen less frequently. Criteria for response were established on the basis of the occurrence of N a and P a within prescribed latencies as well as the interval between the two peaks of about 12–13 msec. The number of identifiable responses diminished with diminishing sensation levels but responses were observed in about one-half of the subjects as low as −5 dB SL.

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Multiple captures (34 double, 6 triple) in standard Sherman live traps accounted for 6.3% of 1355 captures of Peromyscus leucopus (white-footed mice) in forested habitat in southern Illinois, from Oct. 2004 through Oct. 2005. There was a significant positive relationship between both the number and the proportion of multiple captures and estimated monthly population size. Multiple captures were all intraspecific and occurred significantly more often from Nov. through Mar. when animals were not reproductively active, but this was confounded by seasonal changes in abundance. Age/gender distribution of animals in double captures did not differ from that expected from random pairing. We suggest that sociality and synchronous entry of two white-footed mice into traps were the primary determinants of double captures; sensitivity of traps may have been the primary factor in triple captures.

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