Table 2 Shock levels and skin-conductance responses (in square root microSiemens, μS^1/2) to the conditioned stimulus, the unconditioned stimulus (US) and the omitted US ± standard error (significant P values in bold).

Shock level, mA

2.13 ± 0.16

2.20 ± 0.18

0.77

CS^c+ response, μS^1/2

0.27 ± 0.08

0.17 ± 0.04

0.24

CS- response, μS^1/2

0.08 ± 0.04

-0.01 ± 0.04

0.04

Unconditioned response, μS^1/2

0.79 ± 0.11

0.71 ± 0.07

0.56

Omitted US response, μS^1/2

0.26 ± 0.05

0.21 ± 0.03

0.36