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.

Speaker: Dr. Pablo Grassi (MPI Tübingen)

Neuroimaging has consistently shown that storage of visual information in visual working memory (VWM) involves memory-specific activity in early visual areas. However, it is unclear whether this memory-specific activity is in fact relevant for, or reflective of, the storage of visual information per se, or whether it rather reflects feedback-mediated activity from higher-level areas that are responsible for the actual storage of visual information. Moreover, in contrast to the largely consistent and robust neuroimaging findings, studies using non-invasive brain stimulation methods, such as transcranial magnetic stimulation (TMS), report inconsistent effects of visual cortex stimulation during working memory tasks. In this talk, we review existing evidence and present results from four novel TMS experiments specifically designed to investigate the causal role of early visual cortex in working memory. We report retinotopically specific disruption of VWM performance during visual, but not semantic, working memory tasks. Yet, while we observed a retinotopic and task-specific effect in the effectiveness of VWM performance, we did not observe an effect on the fidelity of the VWM representations. This suggests that early visual cortex might not be central to the storage of working memory items.

Speaker: Prof. Niels Henze (University of Tübingen)

Mixed reality allows us to change not only what users see, but also how they perceive their environment and their own bodies. In this talk, I discuss virtual environments and avatars as interactive interfaces rather than mere visual representations. I draw on work on avatar hands, body representation, and motion prediction. I also include recent work on thermal perception and simulated weight to show how virtual bodies can shape what users can do and how they experience doing it. The talk asks what becomes possible when the user’s body itself becomes part of the interface. How can avatars support interaction, alter perceived bodily states, or enable people to experience modified versions of themselves? I will close by briefly discussing how these ideas may extend from VR to AR, where avatar-based manipulations could become part of interaction with the physical world.