The reported experiments presented stimulus words by backward pattern masking. Subjects were assessed for awareness by verbal report of stimulus words. Two response indices of discrimination were measured. 1) Heart rate and
Skin Conductance Response 2) A motor discrimination response.
There were two experimental paradigms:
a) A Pavlovian Conditioning paradigm,
b) A motor discrimination task.
These used: i) supraliminal presentation, ii) subliminal presentation.
Six experiments studied whether subject response measures discriminated stimulus words without the subjects' awareness.
Experiments 1 and 2 used the Pavlovian conditioning paradigm, with a reward and shock UCS respectively. There was no evidence of conditioning without awareness. Experiment 3 introduced the motor discrimination response.
Subjects pressed a lever to the stimulus words to avoid shock paired with a stimulus word. Subjects avoided the delivery of electric shock above chance level whilst not discriminating the stimulus words with their verbal report above chance level. The subjects were defined as unaware of the stimulus words. Experiments 4, 5 and 6 developed the lever press paradigm and found evidence of discrimination without awareness. The psychophysiological responses did not
reveal any conclusive results. Backward pattern masking was an effective technique for presenting stimulus words without the subjects' awareness of what they were. Individual difference effects were strong in all the experiments for both response measures. The evidence is discussed in terms of awareness and unawareness and the implications of interpretation for levels of awareness and the conceptions of consciousness.