Difficult Turned Easy: Suggestion Renders a Challenging Visual Task Simple

Suggestions can cause some individuals to miss or disregard existing visual stimuli, but can they infuse sensory input with nonexistent information? Although several prominent theories of hypnotic suggestion propose that mental imagery can change our perceptual experience, data to support this stance remain sparse. The present study addressed this lacuna, showing how suggesting the presence of physically absent, yet critical, visual information transforms an otherwise difficult task into an easy one. Here, we show how adult participants who are highly susceptible to hypnotic suggestion successfully hallucinated visual occluders on top of moving objects. Our findings support the idea that, at least in some people, suggestions can add perceptual information to sensory input. This observation adds meaningful weight to theoretical, clinical, and applied aspects of the brain and psychological sciences

Modeling mind-wandering: a tool to better understand distraction

When we get distracted, we may engage in mind-wandering, ortask-unrelated thinking, which impairs performance on cognitivetasks. Yet, we do not have cognitive models that make thisprocess explicit. On the basis of both recent experiments thathave started to investigate mind-wandering and introspectiveknowledge from for example meditators, we built a processmodel of distraction in the form of mind-wandering. We thentested the model by predicting performance on tasks used inmind-wandering studies. We showed that we could both predicttask performance as well as the participants’ responses toquestions about what they were thinking about. This improvedunderstanding of mind-wandering could be used in the futureto revise our models of when, how, and why distraction occurs.For example, our model could be used to examine how the effectof distraction on task performance depends on the type ofmind-wandering (e.g., rumination versus day-dreaming)

Exploring the relation between Metacognition, Multi-tasking and stress

When people do multiple tasks at the same time, it is often found that their performance is worse relative to when they do those same tasks in isolation. Indeed, error rates and response times (the Type 1 performance) have been repeatedly found to increase when multitasking. However, one aspect that has received little empirical attention in comparison, is whether observers are aware of these effects (their Type 2 performance). In a previous study, using a simple dual-task visual paradigm, we found that metacognition was unaffected by multitasking. In order to understand if this result could be generalised to other types of multitasking, we further developed a multi-modal paradigm, involving a motor tracking task, a visual detection task, and an auditory n-back task. We made participants perform these tasks in different combinations of single-, dual-, and tripletasking, and asked them to assess their own performance on a trial-by-trial basis. Comparing these different conditions, we discuss our results in the light of the influence that multitasking, and the specific type of task, has both on type 1 and type 2 performance, as well as on participants’ metacognitive bias. Finally, we explore how stress impact these different measures

The Stern-Gerlach Experiment Revisited

The Stern-Gerlach-Experiment (SGE) of 1922 is a seminal benchmark experiment of quantum physics providing evidence for several fundamental properties of quantum systems. Based on today's knowledge we illustrate the different benchmark results of the SGE for the development of modern quantum physics and chemistry. The SGE provided the first direct experimental evidence for angular momentum quantization in the quantum world and thus also for the existence of directional quantization of all angular momenta in the process of measurement. It measured for the first time a ground state property of an atom, it produced for the first time a `spin-polarized' atomic beam, it almost revealed the electron spin. The SGE was the first fully successful molecular beam experiment with high momentum-resolution by beam measurements in vacuum. This technique provided a new kinematic microscope with which inner atomic or nuclear properties could be investigated. The original SGE is described together with early attempts by Einstein, Ehrenfest, Heisenberg, and others to understand directional quantization in the SGE. Heisenberg's and Einstein's proposals of an improved multi-stage SGE are presented. The first realization of these proposals by Stern, Phipps, Frisch and Segr\`e is described. The set-up suggested by Einstein can be considered an anticipation of a Rabi-apparatus. Recent theoretical work is mentioned in which the directional quantization process and possible interference effects of the two different spin states are investigated. In full agreement with the results of the new quantum theory directional quantization appears as a general and universal feature of quantum measurements. One experimental example for such directional quantization in scattering processes is shown. Last not least, the early history of the `almost' discovery of the electron spin in the SGE is revisited.Comment: 50pp, 17 fig

Does social context impact metacognition? Evidence from stereotype threat in a visual search task

While recent studies have emphasized the role of metacognitive judgments in social interactions, whether social context might reciprocally impact individuals’ metacognition remains an open question. It has been proposed that such might be the case in situations involving stereotype threat. Here, we provide the first empirical test of this hypothesis. Using a visual search task, we asked participants, on a trial-by-trial basis, to monitor the unfolding and accuracy of their search processes, and we developed a computational model to measure the accuracy of their metacognition. Results indicated that stereotype threat enhanced metacognitive monitoring of both outcomes and processes. Our study thus shows that social context can actually affect metacognition