Out-of-Body Experience induced by hypnotic suggestion: phenomenology and perceptual characteristics

The aim of this study is the investigation of the perceptual and cognitive characteristics of Out-of- Body Experiences (OBEs) induced by hypnotic induction.Five participants selected for their experience with hypnotic inductions were induced into an OBE and were requested to verbally describe six selected images, either one or two per session, that were located in two different rooms that were hundreds of kilometers from the place where they were under hypnosis.Furthermore, their real-time phenomenological experience was investigated with respect to the minimal phenomenal selfhood (MPS) and the similarities with the characteristics of spatial and temporal perception reported in near death experiences (NDEs).On average, the participants correctly identified 46.7% of the images, whereas two independent judges correctly identified 66.7% of them, compared to a probability of 25% expected due to chance.The phenomenology of their out-of-body perceptual and cognitive experiences revealed a general commonality among all participants. All participants reported a phenomenological experience of a disembodied personal selfhood able to perceive simply by an act of will without the physical limitation of eyesight, to move in the environment instantaneously and exist in a sort of three dimensional world with no awareness of time.The validity of these first person verbal reports was discussed to determine whether they were due to real OBEs or to the participants’ or the hypnotist’s previous knowledge about OBE.

In search of lost time: cognitive and arginine metabolic correlates of temporal dysfunction in the MIA rat model of schizophrenia risk

Abnormal temporal perception is a hallmark characteristic of schizophrenia associated with cognitive impairment, however the relationship between these functions is yet to be characterised within translational models. Using the maternal immune activation (MIA) rat model, this study investigated the contribution of sustained attention and working memory capacity to temporal perception impairments via operant paradigms. In addition, we also investigated the involvement of L-arginine metabolites in timing and cognition via high performance liquid chromatography and liquid chromatography/mass spectrometry. Principally, we identified that underestimation of interval durations (2-8 s) in MIA rats was related to attentional capacity. MIA rats were found to exhibit impaired working memory maintenance, however this was not related to temporal perception. In addition, we identified evidence of MIA impacting PFC L-arginine metabolites, L-citrulline and putrescine, which both correlated with working memory maintenance impairments. MIA also appeared to produce discrete differences in glutamate levels depending on whether inflammation was incited early or late in gestation (gestation day 10/18). Following late gestation MIA exposure, higher glutamate levels in PFC corresponded with poorer sustained attention capacity. These findings represent the first direct identification of a timing-attention relationship within rodents, and provide clues regarding the potential involvement of elevated dopamine in timing-cognition pathology in schizophrenia. Moreover, we present preliminary evidence that changes in L-arginine metabolism have functional consequences for cognition. These outcomes commend the MIA rat model as a tool for potential future investigations exploring the biological instantiation of timing deficits.

Cannabis and Its Different Strains

Previous studies show how time perception can be altered by cannabis consumption, but it is not clear yet whether cannabis produces temporal underproductions or overproductions after acute cannabis intoxication. The present study aimed to analyze a sample of 50 regular cannabis users controlling for cannabis strain (sativa, indica, and hybrid) and to compare their scores in a temporal production task before and after consuming cannabis with a control group of 49 nonusers. Results showed that cannabis intake leads to overproductions, suggesting that regular users’ internal tempo slows down after acute intoxication. However, the analyses of main effects showed that indica users, both at baseline levels and after consuming, reported significant underproductions compared to controls, sativa, and hybrid users, and the cannabis-induced effects had a higher magnitude after smoking in the indica-strain group. Results highlight the relevance of including the type of strain consumed in cannabis studies, and they are discussed in terms of short- and long-term alterations in temporal perception under the light of the self-medication theory and the therapeutic uses of cannabis.

Serial Dependence in Temporal Perception Reveals the Dynamics of Constructing an Internal Reference Frame

Temporal perception is crucial to cognitive functions. To better estimate temporal durations, the observers need to construct an internal reference frame based on past experience and apply it to guide future perception. However, how this internal reference frame is constructed remains largely unclear. Here we showed the dynamics of the internal reference construction from the perspective of serial dependence in temporal reproduction tasks. We found the current duration estimation is biased towards both perceived and reproduced durations in previous trials. Moreover, this effect is regulated by the variability of sample durations. The influence of previous trials was stronger when the observers were exposed to context with more variable durations, which is inconsistent with previous theories that the similarity between successive stimuli induces serial dependence. We proposed a Bayesian model with an adaptive reference updated continuously after each observation, which can better explain the serial dependence observed in temporal perception.

Evidence toward the potential absence of relationship between temporal and spatial heartbeats perception

Many interoceptive tasks (i.e. measuring the sensitivity to bodily signals) are based upon heartbeats perception. However, the temporal perception of heartbeats—when heartbeats are felt—varies among individuals. Moreover, the spatial perception of heartbeats—where on the body heartbeats are felt—has not been characterized in relation to temporal. This study used a multi-interval heartbeat discrimination task in which participants judged the timing of their own heartbeats in relation to external tones. The perception of heartbeats in both time and spatial domains, and relationship between these domains was investigated. Heartbeat perception occurred on average ~ 250 ms after the ECG R-wave, most frequently sampled from the left part of the chest. Participants’ confidence in discriminating the timing of heartbeats from external tones was maximal at 0 ms (tone played at R-wave). Higher confidence was related to reduced dispersion of sampling locations, but Bayesian statistics indicated the absence of relationship between temporal and spatial heartbeats perception. Finally, the spatial precision of heartbeat perception was related to state-anxiety scores, yet largely independent of cardiovascular parameters. This investigation of heartbeat perception provides fresh insights concerning interoceptive signals that contribute to emotion, cognition and behaviour.

Slowing the Body slows down Time (Perception)

Interval timing is a fundamental component of action, and is susceptible to motor-related temporal distortions. Previous studies have shown that concurrent movement biases temporal estimates, but have primarily considered self-modulated movement only. However, real-world encounters often include situations in which movement is restricted or perturbed by environmental factors. In the following experiments, we introduced viscous movement environments to externally modulate movement and investigated the resulting effects on temporal perception. In two separate tasks, participants timed auditory intervals while moving a robotic arm that randomly applied four levels of viscosity. Results demonstrated that higher viscosity led to shorter perceived durations. Using a drift-diffusion model and a Bayesian observer model, we confirmed these biasing effects arose from perceptual mechanisms, instead of biases in decision making. These findings suggest that environmental perturbations are an important factor in movement-related temporal distortions, and enhance the current understanding of the interactions of motor activity and cognitive processes.