Effects of Unpaired Pre-Acquisition Exposure of CS and UCS on Classical Conditioning of the Nictitating Membrane Response of the Albino Rabbit

The effects of the presentation, prior to acquisition training of (1) “no stimulation,” (2) CS alone trials, (3) UCS alone trials, and (4) CS-UCS unpaired trials were investigated in conditioning and extinction of the nictitating membrane response. The principal findings were: (a) significantly higher blink rates in adaptation for the groups receiving the UCS, (b) no differences among groups in acquisition, (c) greater resistance to extinction by groups receiving the CS in adaptation, as evidenced by significant differences in spontaneous recovery, and (d) a significant over-all increase in UCR magnitude in adaptation and acquisition.