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[Image: see text] Psychedelic drugs are increasingly being incorporated into therapeutic contexts for the purposes of promoting mental health. However, they can also induce adverse reactions in some individuals, and it is difficult to predict before treatment who is likely to experience positive or adverse acute effects. Although consideration of setting and dosage as well as excluding individuals with psychotic predispositions has thus far led to a high degree of safety, it is imperative that researchers develop a more nuanced understanding of how to predict individual reactions. To this end, the current systematic review coalesced the results of 14 studies that included baseline states or traits predictive of the acute effects of psychedelics. Individuals high in the traits of absorption, openness, and acceptance as well as a state of surrender were more likely to have positive and mystical-type experiences, whereas those low in openness and surrender or in preoccupied, apprehensive, or confused psychological states were more likely to experience acute adverse reactions. Participant sex was not a robust predictor of drug effects, but 5-HT2AR binding potential, executive network node diversity, and rACC volume may be potential baseline biomarkers related to acute reactions. Finally, increased age and experience with psychedelics were individual differences related to generally less intense effects, indicating that users may become slightly less sensitive to the effects of the drugs after repeated usage. Although future well-powered, placebo-controlled trials directly comparing the relative importance of these predictors is needed, this review synthesizes the field’s current understanding of how to predict acute reactions to psychedelic drugs.

Psychedelic drugs are well-known for transiently altering perception, and in particular, for their visual effects. Although scientific interest into the substances’ effects on perception increased during the first era of psychedelic research during the early to mid-20th century, there is currently no source where these findings have been synthesized. In addressing this gap, the current narrative review found that psychedelics were examined for their influences across all levels of the visual system (e.g., retinal, cortical, subcortical, simple visual processing, complex imagery, hallucinations). Psychedelics were also shown to affect auditory discrimination/generalization, neural correlates of auditory processing, and led to auditory hallucinations in subsets of participants. Several studies demonstrated that psychedelics can distort representations of body schema and time perception. Concerns regarding methodological standards of this era are a limitation to the findings and are discussed. Collectively, this review preserves and increases the accessibility of the work done by pioneering psychedelic/perception researchers, synthesizes findings, and critically analyzes areas of discrepancy to inform future studies.

Research into the basic effects and therapeutic applications of psychedelic drugs has grown considerably in recent years. Yet, pressing questions remain regarding the substances' lasting effects. Although individual studies have begun monitoring sustained changes, no study to-date has synthesized this information. Therefore, this systematic review aims to fill this important gap in the literature by synthesizing results from 34 contemporary experimental studies which included classic psychedelics, human subjects, and follow-up latencies of at least two weeks. The bulk of this work was published in the last five years, with psilocybin being the most frequently administered drug. Enduring changes in personality/attitudes, depression, spirituality, anxiety, wellbeing, substance misuse, meditative practices, and mindfulness were documented. Mystical experiences, connectedness, emotional breakthrough, and increased neural entropy were related to these long-term changes in psychological functioning. Finally, with proper screening, preparation, supervision, and integration, limited aversive side effects were noted by study participants. Future researchers should focus on including larger and more diverse samples, lengthier longitudinal designs, stronger control conditions, and standardized dosages.

Older adulthood can be characterized by various cognitive and affective changes. In general, older adults show declines in creativity and executive functioning. They also score lower in openness to experience, empathy, and many suffer from a paucity of meaningful experiences. Further, depression, pessimism, and suicide can be major concerns for this population. Although currently there are few interventions that can effectively address these changes, recent findings from psychedelic science suggest myriad parallels between the effects of these drugs and the cognitive/affective shifts seen in older adulthood. Studies have shown that psychedelics are associated with enhanced creativity and executive functioning. They can also lead to increases in openness and empathy, and induce personally meaningful experiences. Lastly, psychedelics’ efficacy for treating mood disorders and their role in palliative care are rapidly growing areas of scientific research. In this article, we analyze findings from contemporary psychedelic studies and integrate them with research on cognitive/affective changes in older adulthood to assess whether these drugs have potential to be incorporated into older adult research. We also assess the intuitive follow-up questions of potential mechanisms of action and safety concerns. Findings indicate that psychedelics have effects on a number of cognitive/affective processes that are altered in older adulthood, and are relatively safe when used with professional preparation and supervision. Increased neuroplasticity, neurogenesis, connectedness, and mystical experiences have been argued to underlie cognitive/affective changes. However, further research is needed to overcome current experimental limitations such as generalizability, unstandardized dosages, inadequate controls, and self-selection/experimenter biases.

A variety of attentional and perceptual changes occur in peri-hand space, including increases in visual temporal acuity. These changes in cognition have been related to an increase in magnocellular visual processing. Other magnocellular-related processes have been shown to enhance temporal sensitivity and lead to time overestimation. We hypothesized that a similar slowing of time perception would occur in peri-hand space. To this end, we had participants complete either a temporal bisection task or a verbal time estimation task with their hands near to or far from the test stimuli. Contrary to our predictions, we found no differences in time perception in peri-hand space. We situate our findings within the context of a contemporaneous study by Qi, Wang, He, and Du (2019), which produced conflicting results when using a temporal reproduction task to investigate the same phenomenon. The disparate results might relate to the fragility of peri-hand effects and/or to the tasks tapping into different aspects of time perception. Further research will be needed to fully elucidate the nuances of peri-hand space and temporal processing.

During the 1950s and 1960s, there was a tremendous surge in research into the effects of psychedelic drugs. When discussing this period of research, the discovery of the psychoactive properties of LSD in 1943 is often presented as the main, and sometimes only, driving force of the boom in research. This "Great Person," or "Great Chemical," historiographical lens fails to acknowledge other factors that were fundamental in setting the stage for the research. In particular, other psychedelic drugs, such as mescaline, were already being probed for their uses in psychotherapy and as models for psychosis before the effects of LSD had been discovered. Psilocybin and other classical psychedelics had also been discovered by Western researchers around the same time as the synthesis of LSD. Additionally, many of the dominant zeitgeists (e.g., pharmacological, psychoanalytic, and humanistic) in psychology during this period were congruent with psychedelic research. This article argues that while the discovery of LSD may have been a catalyst for psychedelic research in the 1950s and '60s, there was a broader psychedelic zeitgeist that deserves acknowledgement for setting the stage.

It is known that visual processing is altered for objects near the hands as well as for objects near the imagined position of the hands, indicating that the imagination can be used to remap peri-ha...

Postural changes and the maintenance of postural stability have been shown to affect many aspects of cognition. Here we examined the extent to which selective visual attention may differ between standing and seated postures in three tasks: the Stroop color-word task, a task-switching paradigm, and visual search. We found reduced Stroop interference, a reduction in switch costs, and slower search rates in the visual search task when participants stood compared to when they sat while performing the tasks. The results suggest that the postural demands associated with standing enhance cognitive control, revealing broad connections between body posture and cognitive mechanisms.

Meditation commonly gives rise to the feeling that the self and the surrounding world are no longer separate, as if the boundary between them has dissolved. We propose this may occur due to alterations in representations of peripersonal space (PPS), the reachable space surrounding the body which is integral to a sense of where one’s bodily “self” is located in space. Thirty-one participants completed an auditory oddball paradigm before and after a guided meditation, during which we measured their P3 evoked potential, a marker of attentional salience. Pre-meditation, participants exhibited an enhanced attentional response to stimuli presented within PPS, relative to beyond PPS. Post-meditation, this PPS attentional enhancement was negated, with no distinction between responses to stimuli within versus beyond PPS. The results suggest that meditation leads to a constriction of PPS boundaries, even in novice meditators, elucidating one potential cause of the perceptual changes associated with meditation.

Psychedelic drugs and virtual reality (VR) each have the capacity to disrupt the rigidity and limitations of typical conscious experience. This article delineates the parallels among psychedelic and VR states as well as their potential synergistic applications in clinical and recreational settings. Findings indicate that, individually, psychedelics and VR are used in analogous ways to alter sensory experience and evoke awe. They are also both used in tandem with traditional therapies to treat a variety of mood disorders; their shared capacity to transiently alter perspective and disrupt rigid patterns of mental experience may underly their analogous and transdiagnostic therapeutic uses. In terms of their combined applications, a number of recreational users currently utilize psychedelics and VR together to enhance their experience. We propose that VR may be a useful tool for preparing hallucinogen-naïve participants in clinical trials for the sensory distortions experienced in psychedelic states. Given the critical role of “setting” in psychedelic treatment outcomes, we also detail how VR could be used to optimize the environment in psychedelic sessions. Finally, we provide considerations for future studies and detail how advancements in psychedelic and VR research can inform one another. Collectively, this article outlines a number of connections between psychedelics and VR, and, more broadly, is representative of growing scientific interest into the interactions among technology, psychopharmacology, and mental health.

Theories of embodied perception hold that the visual system is calibrated by both the body schema and the action system, allowing for adaptive action-perception responses. One example of embodied perception involves the effects of tool use on distance perception, in which wielding a tool with the intention to act upon a target appears to bring that object closer. This tool-based spatial compression (i.e., tool-use effect) has been studied exclusively with younger adults, but it is unknown whether the phenomenon exists with older adults. In this study, we examined the effects of tool use on distance perception in younger and older adults in 2 experiments. In Experiment 1, younger and older adults estimated the distances of targets just beyond peripersonal space while either wielding a tool or pointing with the hand. Younger adults, but not older adults, estimated targets to be closer after reaching with a tool. In Experiment 2, younger and older adults estimated the distance to remote targets while using either a baton or a laser pointer. Younger adults displayed spatial compression with the laser pointer compared to the baton, although older adults did not. Taken together, these findings indicate a generalized absence of the tool-use effect in older adults during distance estimation, suggesting that the visuomotor system of older adults does not remap from peripersonal to extrapersonal spatial representations during tool use.

Perceptual load theory claims that attentional processing of distractors in the visual environment is dependent upon the availability of perceptual resources, and recent research has attempted to link this selective attention theory to more classic ideas on visual search. In the present study, we investigated how perceptual load could be linked to a prominent visual search theory: guided search. Our findings suggest that any volitional attempt at attentional guidance only hindered attention under low perceptual load, whereas attentional guidance could be highly effective under high perceptual load. Importantly, guided search only proved effective when participants could utilise knowledge about the display consistently from trial-to-trial. This finding parallels previous evidence about visual search, extends it to perceptual load theory and further demonstrates the rich potential in uniting visual search and visual selection studies.

People physically distance themselves from competitors and the disliked and cooperate less with those who are further away. We examine whether social interaction can also impact the space people perceive between themselves and others by measuring the influence of competitive dynamics on visual perception. In two experiments, participants played a ball toss game until they reached a target score. In Experiment 1, a confederate stood across the room from the participant and either a) played the same game competitively, b) played the same game cooperatively, or c) observed the participant without playing, while in Experiment 2, two participants played the same versions of the game with each other. After the game, participants provided an estimate of the distance between themselves and the other player. Participants in Experiment 1 who competed with the confederate consistently judged her to be more distant than participants who cooperated with the confederate or played alone. In Experiment 2, players who lost the competition perceived more distance between themselves and their opponents than did players who won, suggesting that the experience of losing a competition drives this perceptual distancing. These findings demonstrate the power of a socially distancing interaction to create perceptual distance between people.

Neurological changes in older adults suggest that their mental representation of peripersonal space, the space around their bodies, might be degraded compared with that of young adults. These changes may lead to differences in how attention is allocated within peripersonal space, affecting how older adults plan and guide their actions. In the present study, we show that there are indeed profound differences between the spatial representations of older and young adults: In a task involving simple hand movements, young adults adopted an attentional reference frame centered on the hand, and older adults adopted a reference frame centered on the body. Such differences may help to explain age-related changes observed in the performance of many common movement tasks.

Our mental processing of the visual world is not independent of our physical actions within it. Placing objects near one’s hands and interacting with objects using tools can enhance visual perception, bias and prolong the allocation of attention, and distort memory in systematic ways. This suggests that the world within our reach is cognitively different from the world beyond reach. In this review, we examine the evidence supporting this conclusion, focusing on the cognitive and neural mechanisms that underlie these effects, the parameters that may control their emergence, and their potential practical applications.

Recent investigations have revealed enhanced processing of information that is presented within hand space. A potential consequence of such enhancement could be that simultaneous processing of information outside of hand space is diminished, but this possibility has yet to be tested. Here, we considered the possibility that the hands can serve as a natural remedy for unwanted interference, by acting as a physical manifestation of the attentional window. Participants performed a flanker task in which they identified a central target letter in the presence of flanking letters that varied in their degrees of compatibility with the target. Participants either held their hands around the target, such that the flankers appeared outside of the hands (but in clear view), or held their hands away from the display, and thus not around any of the stimuli. Flanker interference was markedly reduced when the hands were around the target, and these effects were not attributable to visual differences across the conditions. Collectively, these results indicate that the hands effectively shield attention from visual interference.

Recently, several changes in perception, attention, and visual working memory have been reported when stimuli are near to compared to far from the hands, suggesting that such stimuli receive enhanced scrutiny. A mechanism that inhibits the disengagement of attention from objects near the hands, thus forcing a more thorough inspection, has been proposed to underlie such effects. Up until now, this possibility has been tested only in a limited number of tasks. In the present study we examined whether changes in one's global or local attentional scope are similarly affected by hand proximity. Participants analysed stimuli according to either their global shape or the shape of their constituent local elements while holding their hands near to or far from the stimuli. Switches between global and local processing were markedly slower near the hands, reflecting an attentional mechanism that compels an observer to more fully evaluate objects near their hands by inhibiting changes in attentional scope. Such a mechanism may be responsible for some of the changes observed in other tasks, and reveals the special status conferred to objects near the hands.

Recent research has shown that being able to interact with an object causes it to be perceived as being closer than objects that cannot be interacted with. In the present study, we examined whether that compression of perceived space would be experienced by people who simply observed such interactions by others with no intention of performing the action themselves. Participants judged the distance to targets after observing an actor reach to an otherwise unreachable target with a tool (Experiment 1) or illuminate a distant target with a laser pointer (Experiment 2). Observing either type of interaction caused a compression of perceived space, revealing that a person's perception of space can be altered through mere observation. These results indicate that shared representations between an actor and observer are engaged at the perceptual level easily and perhaps automatically, even in the absence of cooperation or an observer's own intention to interact.

Reaching for an object with a tool has been shown to cause a compressed perception of space just beyond arm's reach. It is not known, however, whether tools that have distal, detached effects at far distances can cause this same perceptual distortion. We examined this issue in the current study with targets placed up to 30m away. Participants who illuminated targets with a laser pointer or imagined doing so consistently judged the targets to be closer than those who pointed at the targets with a baton. Furthermore, perceptual distortions that arose from tool-use persisted in memory beyond the moment of interaction. These findings indicate that remote interactions can have the same perceptual consequences as physical interactions, and have implications for an action-specific account of perception. (PsycINFO Database Record (c) 2011 APA, all rights reserved). Language: en

International audience; In this report, we examine whether and how altered aspects of perception and attention near the hands affect one's learning of to-be-remembered visual material. We employed the contextual cuing paradigm of visual learning in two experiments. Participants searched for a target embedded within images of fractals and other complex geometrical patterns while either holding their hands near to or far from the stimuli. When visual features and structural patterns remained constant across to-be-learned images (Exp. 1), no difference emerged between hand postures in the observed rates of learning. However, when to-be-learned scenes maintained structural pattern information but changed in color (Exp. 2), participants exhibited substantially slower rates of learning when holding their hands near the material. This finding shows that learning near the hands is impaired in situations in which common information must be abstracted from visually unique images, suggesting a bias toward detail-oriented processing near the hands.

There are a variety of reasons someone might engage in risky behaviors, such as perceived invulnerability to harm or a belief that negative outcomes are more likely for others than for oneself. However, these risk-taking biases are often measured at a decision-making level or from the developmental perspective. Here we assessed whether or not risk-taking influenced perceptual judgments associated with risk. Participants were provided an objective task to measure individual differences in the perception of physical dimensions (i.e., actual size of a balloon) versus the perception of risk (i.e., size at which the balloon would explode). Our results show that specific differences in risk-taking personalities produce specific differences in perceptual judgments about risk, but do not affect perception of the actual dimensions. Thus, risk-takers differ from non-risk-takers in the perceptual estimations they make about risks, and therefore may be more likely to engage in dangerous or uncertain behaviors because they perceive risks differently.

People perceive individual objects as being closer when they have the ability to interact with the objects than when they do not. We asked how interaction with multiple objects impacts representations of the environment. Participants studied multiple-object layouts, by manually exploring or simply observing each object, and then drew a scaled version of the environment (Exp. 1) or reconstructed a copy of the environment and its boundaries (Exp. 2) from memory. The participants who interacted with multiple objects remembered these objects as being closer together and reconstructed smaller environment boundaries than did the participants who looked without touching. These findings provide evidence that action-based perceptual distortions endure in memory over a moving observer’s multiple interactions, compressing not only representations between touched objects, but also untouched environmental boundaries.

In this chapter, we describe how attention and memory interact to determine the extent and quality of our visual interactions with the world. We begin by considering the ways in which attention acts as a gatekeeper to visually-based memory. We then review the role attention plays in the maintenance of visual information in both short-term (working) and long-term memory. Finally, we describe examples of tasks and situations in which the contents of visual memory reciprocally affect the guidance of attention through visual displays.

It has been said that the imagination is a powerful tool. We show here that, in reality, this claim may be more than simply a metaphor. Recent studies have revealed that items near the hands benefit from enhanced visual analysis (Abrams, Davoli, Du, Knapp, & Pauli, 2008; Reed, Grubb, & Steele, 2006; Schendel & Robertson, 2004). These results are thought to reflect the importance of representing objects and events that are in close proximity to the body, such as objects that are soon to be grasped or those that must be avoided. Quite naturally, all previous studies that have found perceptual enhancement near the hands have had subjects assume a posture in which their hands were placed close to a visual display. We show here for the first time that the same benefits can occur when one simply imagines such postures.

Recent evidence has suggested that new objects capture attention solely because they are typically accompanied by a unique luminance transient. In the present study, we presented a stationary pattern mask after an array of placeholders but before a subsequent search display. This allowed all of the search elements to be presented simultaneously, thereby eliminating the unique luminance transient associated with the appearance of any new objects. Under these circumstances, new objects still captured attention. In another experiment, we jiggled the mask. This caused new objects to lose their advantage. We discuss implications for the importance of new objects, and the attentional consequences of motion.

Heinrich Kluver (1897–1979) was one of the twentieth century's most widely influential scientists, a pioneer in the fields of psychology, neuroanatomy, and psychochemistry. Kluver is perhaps best k...

The present study explored the manner in which hand position may affect visual processing. We studied three classic visual attention tasks (visual search, inhibition of return, and attentional blink) during which the participants held their hands either near the stimulus display, or far from the display. Remarkably, the hands altered visual processing: people shifted their attention between items more slowly when their hands were near the display. The same results were observed for both visible and invisible hands. This enhancement in vision for objects near the hands reveals a mechanism that could facilitate the detailed evaluation of objects for potential manipulation, or the assessment of potentially dangerous objects for a defensive response.