Eyeblink conditioning with a noise burst as unconditioned stimulus.

BACKGROUND: The aim of this study was to determine if a white noise burst could be used as an effective unconditioned stimulus (US) to produce differential conditioning of eyeblink responses that were recorded as EMG activity of the orbicularis oculi.

METHOD: Two fear-relevant stimuli served as conditioned stimuli (CS). An angry woman’s face (CS+) was consistently followed by a white noise burst (US) with 100 dB intensity and 100 milliseconds in duration.  A fearful face of the same woman (CS-) was not followed by the US. CS duration was 500 milliseconds (ms) for 18 participants (long interval group), and 250 ms for 19 participants (short interval group). The US was presented in both groups immediately after terminating CS+.

RESULTS: The results showed acquisition of differential conditioning in the long interval group, but not in the short interval group.

CONCLUSIONS: These results suggest that a white noise burst as US could be used in one single experimental procedure which was capable of simultaneously producing conditioning in neural, autonomic and somatomotor response systems.