Speaker: Dr. Sascha Meyen (University of Tübingen)
Research on unconscious processing suffers from a methodological fallacy. In many studies on unconscious processing, a priming paradigm is used. There, it is argued that a prime stimulus can influence the processing of a subsequently presented target stimulus, even if the prime is not consciously perceived. Evidence for such findings typically comes from two tasks: In an indirect task, response times to the target stimulus are shown to be affected by the prime stimulus. In a direct task, participants are then asked to discriminate the prime stimulus, showing very low performance. This pattern of results seems to demonstrate that response times in the indirect task are more sensitive to the prime stimulus than participants’ direct task reports. Based on this apparent difference in sensitivities, researchers routinely infer that the prime stimulus was processed unconsciously, that is, the sensitivity of response times to the prime stimuli was higher than the sensitivity of participants' direct reports to them. Here is the problem: Sensitivities in the indirect task are never actually calculated. To resolve this issue, we conduct the appropriate relative sensitivity analysis in which we show that sensitivities in both tasks are very similar. Thus, there is a lack of evidence for a difference between the two tasks and, thus, no empirical basis for claims about unconscious priming. We demonstrate the same problem in a different paradigm on implicit learning. Given this pervasive, fundamental methodological flaw, reports of unconscious processing and implicit learning require serious reevaluation.