This dataset includes pupil size response (PSR), skin conductance response (SCR), electrocardiogram (ECG) and respiration measurements. Also included are CS and US information, keypress responses, keypress response times, key correctness and shock expectancy ratings at the end of the experiment for 71 healthy unmedicated participants (33 males and 38 females aged 24.2+/-3.9 years) participating in a 3 conditions x 3 experimental sessions repeated-measures design to assess the return of fear. CS were colored triangles (yellow/red/blue). US consisted of a 500 ms train of 250 square pulses with individual pulse width of 0.2 ms. SOA between the CS onset and US was 3.5 s. CS and US co-terminated. The ITI was randomly determined as discrete value...