TABLE 2.

Comparison of Photoelectric Cell and Electro-myographic (EMG) Methods for Recording Eye Blinks Following Startling Auditory Pulses Presented Alone and After Prepulses to Seven Healthy Adults^a

	Photoelectric Cell		EMG		Mean Difference
Variable	Mean	SD	Mean	SD
Millivolt level at  start of trialb
Pulse trials	136.38	70.45	8.43	2.58	0.002c
Prepulse trials	147.74	104.09	7.81	4.21	0.001c
Maximum  amplitude of  peak (mV)b
Pulse trials	2222.61	1462.06	106.02	58.04	7.48c
Prepulse trials	907.47	591.63	42.78	23.94	1.83c
Time of peak  (msec)
Pulse trials	94.08	12.54	95.55	13.41	1.47
Prepulse trials	72.55	22.53	84.45	9.06	11.90
Percentage  prepulse  inhibitiond	59.89	11.53	59.23	9.38	0.66

^aDifferences were examined with paired t tests; none was significant at p≤0.10.

^bRaw values were transformed to t scores to resolve method scaling differences (mean=50, SD=10).

^cDifference in t score.

^dCalculated as 100 − ([peak in prepulse trials/peak in pulse trials] × 100).