Six experimentalSs were used to condition the reaction‐to‐shock (UCS) of the alpha rhythm of the EEG to a subliminal auditory stimulus of 500 c.p.s. (CS). A matched control group of sixSs was similarly stimulated, but shock and the CS were never paired. On test trials there was a difference between experimental and control groups in reaction to the subliminal stimulus, yielding evidence of conditioning in the experimental group. A neutral subliminal stimulus of 800 c.p.s. was also used to test ability to discriminate between subliminal stimuli. Large individual differences were found, and results are indeterminate. The findings raise neurophysiological questions in terms of cue and arousal functi