[Slip technique, process dissociation model and multinomial modeling: new tools for experimental detection of...

The study reported here was conducted as a test of the so-called "weak Freudian hypothesis", which claims that unconscious thoughts are relevant for the generation of speech errors. Spoonerisms were induced experimentally using the so-called SLIP technique. Motley and Baars (1976) demonstrated an increase in speech error rates when spoonerisms were primed semantically. The extensively discussed problems of "unawareness" of briefly presented stimuli were circumvented by using a modified version of Jacoby's process dissociation technique which allows a model-based estimation of conscious and unconscious processes within a task. The two reported experiments combined a wordstem completion task for estimating probabilities of perceptual processes and a SLIP task under identical perceptual conditions. A joint multinomial model was constructed for data analysis. The SLIP technique was successfully applied using German stimuli, adequate experimental variations raised the error rate from 7% in experiment 1 to 19% in experiment 2. Neither the replication of Motley and Baars' results nor unconscious priming of speech errors were statistically confirmed. Despite this negative result, the descriptive pattern of parameter estimates is psychologically meaningful: primes that remained unconscious resulted in a higher speech error probability than primes that were perceived consciously. Conscious perception might trigger control processes that act in opposition of speech errors. Statistical problems of the particular multinomial model and possible solutions in future research are discussed.