Human Vision Reconstructs Time to Satisfy Causal Constraints

The goal of perception is to infer the most plausible source of sensory stimulation. Unisensory perception of temporal order, however, appears to require no inference, because the order of events can be uniquely determined from the order in which sensory signals arrive. Here, we demonstrate a novel perceptual illusion that casts doubt on this intuition: In three experiments ( N = 607), the experienced event timings were determined by causality in real time. Adult participants viewed a simple three-item sequence, ACB, which is typically remembered as ABC in line with principles of causality. When asked to indicate the time at which events B and C occurred, participants’ points of subjective simultaneity shifted so that the assumed cause B appeared earlier and the assumed effect C later, despite participants’ full attention and repeated viewings. This first demonstration of causality reversing perceived temporal order cannot be explained by postperceptual distortion, lapsed attention, or saccades.

EXPRESS: Fooling System 1 in the field of perception: Failure to Intuitively Detect Attribute Substitution in the Flushtration Count Illusion

To facilitate our interactions with the surroundings, the human brain sometimes reshapes the situations that it faces in order to simplify them. This phenomenon has been widely studied in the context of reasoning, especially through the attribute substitution error. It has however been given much less attention in the field of perception. Recent research on the bat-and-ball problem suggests that reasoners are able to intuitively detect attribute substitution errors. Using a perceptual illusion drawn from the field of magic, we investigate the extent to which a perceptual form of attribute substitution depends on executive resources and can be detected. We also investigate the relationship between susceptibility to attribute substitution error in the flushtration count illusion and in a French adaptation of the bat-and ball problem. Finally, we investigate the link between the intuitive cognitive style (assessed by the Cognitive Reflection Test) and the susceptibility to the flushtration count illusion. Our results suggest that participants do not detect perceptual attribute substitution error, that this phenomenon could be independent of the executive resources allocated to the task, and could rest on mechanisms distinct from those that produce errors in reasoning. We discuss differences between these two phenomena, and factors that may explain them.

Feeling Present in Virtual Environments

We compare and contrast different current theoretical accounts of telepresence, including presence as a pretence (a simulation of reality), as pretending (making believe the virtual world is real), as a perceptual illusion (“the illusion of non-mediation”), and as embodied attention to the surrounding (or apparently surrounding) environment. These views are well-accepted in the field, and can be seen as contributing to a virtual travel experience, which is a kind of illusion. When we feel highly present, we believe in the perceived world in which we experience ourselves to be—it is in that moment real to us. Creating that effect is a key part of a convincing digital travel experience. To have that experience, we must be attending to the digital world, feeling as if we are physically surrounded by it. Our imaginations are involved in how we perceive our surroundings, and in how we conceptualise being there.

The zebra finch auditory cortex reconstructs occluded syllables in conspecific song

Sensory input provides incomplete and often misleading information about the physical world. To compensate, the brain uses internal models to predict what the inputs should be from context, experience, and innate biases. For example, when speech is interrupted by noise, humans perceive the missing sounds behind the noise, a perceptual illusion known as phonemic (or auditory) restoration. The neural mechanisms allowing the auditory system to generate predictions that override ascending sensory information remain poorly understood. Here, we show that the zebra finch (Taeniopygia guttata) exhibits auditory restoration of conspecific song both in a behavioral task and in neural recordings from the equivalent of auditory cortex. Decoding the responses of a population of single units to occluded songs reveals the spectrotemporal structure of the missing syllables. Surprisingly, restoration occurs under anesthesia and for songs that the bird has not heard. These results show that an internal model of the general structure of conspecific vocalizations can bias sensory processing without attention.

No specific relationship between hypnotic suggestibility and the rubber hand illusion: a commentary with new and verification analyses

In a recent study, Lush et al. (Nat Commun 11, 4853, 2020) claimed that they found “substantial relationships” between hypnotizability and experimental measures of the rubber hand illusion. The authors proposed that hypnotizable participants control their phenomenology to meet task expectations arising from the experimental paradigm. They further suggest that the rubber hand illusion “may or may not” be entirely explained by hypnotic suggestions driven by task expectancies and therefore could reflect top-down control of perception, instead of multisensory mechanisms. However, in reanalyzing their data, we observe no significant relationships between hypnotic suggestibility and the rubber hand illusion when quantified using a control condition in line with the authors’ preregistered hypothesis. Furthermore, we note that the relationships that the authors describe are weak and observed for a visual “hallucination” control experience and in the control condition, indicating a general influence of hypnotizability on cognition, rather than sensations that specifically relate to the rubber hand illusion. Overall, the results fit well with the view that the rubber hand illusion is a perceptual illusion driven primarily by multisensory mechanisms.

Silence-cued stop perception: Split decisions

Bastian, Eimas, & Liberman (1961) found that listeners heard a [p] when a silence of more than 50ms was inserted between the [s] and the [l] in a recording of the word slit. It has long been known that silence is an important cue in stop consonant perception. Nevertheless, it is surprising that a short interval of silence can substitute for something as acoustically and articulatorily complex as a phoneme. In the present work, we replicate and expand upon this study to further examine the phenomenon of silence-cued stop perception. We demonstrate the ‘Split Effect’ in a previously unexplored set of environments, analyze factors that contribute to the identity of silence-cued stops, and lay the groundwork for further investigation of the acoustic and non-acoustic factors that contribute to this perceptual illusion. Our study demonstrates an experimental paradigm for studying the genesis of such effects synchronically and in a controlled setting.

Integrating the world of presence theory: Illusion, pretence, attending, and pretending

We selected four fragments from the world of presence theory for particular attention. These are: presence as a perceptual illusion, as a pretence, as attending to an external world, and as pretending the virtual is real. We reflect on and try to unite these fragments into a fairly coherent and perhaps more general view of the nature of presence, one that may help integrate insights into both ‘natural’ and mediated presence. One conclusion from this work is that when we feel present, we believe that what is happening is real, in the moment, whether it is in the physical world or in a virtual reality (VR). In other words, when we feel really present in an environment it is real for us. If presence in VR is an illusion, so is presence in the physical world. Presence in VR requires imagination and belief (though not make-believe), and so does presence in the physical world.

The Impact of Experimentally Induced Limb Ischemia on the Rubber Hand Illusion

The rubber hand illusion (RHI) is a perceptual illusion in which one experiences an object as part of their body when synchronous visuo-tactile stimulation is applied to one’s hand and the object. There are a variety of factors that can impact the occurrence of the RHI. In the present study, we demonstrate that experimentally induced peripheral ischemia can impact the RHI, namely it can result in larger alterations to the perceived position of one’s hand. This study suggests that alterations to the cardiovascular system may be a source of individual differences in the RHI literature. Future studies with samples of individuals with cardiovascular pathology are recommended.