PerPsych: An iPadOS-based open-source neuropsychological software for time perception assessment

Time perception is an important aspect of cognitive function that can be affected by mental illness and brain disease. Neuropsychological tests often assess time perception using computer displays, but smartphone or tablet software may offer some advantages. In this study, we present PerPsych, an open-source, iPadOS-based neuropsychological tool for testing time perception. PerPsych has the following features:•It is designed natively for iPadOS, using the low-level Metal interface to access the graphics processing unit for high-timing performance.•It allows researchers to conduct studies on time perception in individuals with cognitive impairment using a simple and user-friendly interface.•It supports various experimental paradigms and parameters for measuring time perception, such as duration estimation, production, and reproduction.

Association between self-perceived consultation time and understanding of the prescribed treatment: An analysis of a national survey in Peru

OBJECTIVE

To assess the relationship between the self-perceived consultation time and the knowledge of the proposed treatment.

METHODS

Secondary data from a 2015 national survey of health services in Peru were analyzed. The self-perceived consultation time was calculated by asking how long it took from when you entered the consultation until you departed. It was then categorized as low, medium, and high. Five self-reported questions were used to construct a knowledge of the prescribed treatment. Adjusted regression models from the Poisson family models were used to evaluate the relationship. We report adjusted prevalence ratios (aPR) with their 95% confidence intervals (95%CI).

RESULTS

A total of 9939 outpatients were analyzed, with 58% women; the average age was 44 years; and 45.4% had higher education. Using low self-perceived consultation time as references, medium and high consultation times were associated with understanding the prescribed treatment (aPR=1.17; 95%CI, 1.04-1.33 and aPR=1.30; 95%CI, 1.20-1.40, respectively).

CONCLUSION

Patients who reported a medium and high self-perceived consultation time better understood the prescribed treatment.

IMPLICATIONS FOR PRACTICE

Healthcare professionals should strive to maximize consultation time to ensure effective communication and improve patient knowledge of treatments, improving overall patient satisfaction and health outcomes.

Awe and time perception

The aim of this study was to systematically examine the effect of awe-inducing stimuli on the judgment of time. Three experiments were conducted using temporal bisection tasks in which participants viewed awe-inducing and no awe-inducing images presented for different durations and were asked to judge whether their duration was similar to a short or long anchor duration. Images of panoramic landscapes and images of the faces of well-known and admired people were used in experiments 1 and 2, respectively. In experiment 3, they did not judge the duration of the images, but that of a neutral stimulus occurring during the presentation of images. In each experiment, participants rated the awe-inducing and no-awe-inducing images according to their components: admiration, beauty, awe, emotional valence, arousal, symbolic self-size, and full-body self-size. Results consistently showed significant time distortions when participants viewed the different awe-inducing images compared to the no-awe images, although the effect was weaker for the images of faces than for those of landscapes. Time distortion took the form of temporal lengthening in Experiments 1 and 2 and shortening in Experiment 3. These different temporal distortions are consistent with attention effects due to awe-inducing stimuli which capture attention to the detriment of time processing.

Effects of the perceived temporal distance of events on mental time travel and on its underlying brain circuits

Mental Time Travel (MTT) allows us to remember past events and imagine future ones. According to previous literature, the Temporal Distance of events affects MTT: our ability to order events worsens for close, compared to far, events. However, those studies established distances a-priori, albeit the way we perceive events' temporal distance may subjectively differ from their objective distance. Thus, in the current study, we aimed to investigate the effects of Perceived Temporal Distance (PTD) on the MTT ability and the brain areas mediating this process. Thirty-three healthy volunteers took part in an fMRI MTT task. Participants were asked to project themselves into the past, present, or future, and to judge a series of events as relative-past or relative-future, in relation to the adopted time location. Outside the scanner, participants provided PTD estimates for each stimulus of the MTT task. Participants' performance and functional activity were analyzed as a function of these estimations. At the behavioural level, PTD predicts the modulation of the performance for relative-past and relative-future. Bilateral angular gyrus, retrosplenial cortex, temporo-parietal region and medial, middle and superior frontal gyri mediate the PTD effect. In addition to these areas, the closer the relative-future events are perceived, the higher the involvement of left parahippocampal and lingual gyri and right cerebellum. Thus, perceived proximity of events activates frontal and posterior parietal areas, which therefore might mediate the processing of PTD in the cognitive spatial representation of time. Future proximity also activates cerebellum and medial temporal areas, known to be involved in imaginative and constructive cognitive functions.

Induction of altered states of consciousness during Floatation-REST is associated with the dissolution of body boundaries and the distortion of subjective time

Floatation-REST (Reduced Environmental Stimulation Therapy) minimizes stimulation of the nervous system by immersing subjects in an environment without sound or light while they effortlessly float in thermoneutral water supersaturated with Epsom salt. Here we investigated the relationship between altered states of consciousness (ASC) and its association with the affective changes induced by Floatation-REST. Using a within-subject crossover design, 50 healthy subjects were randomized to 60 min of Floatation-REST or 60 min of Bed-REST (an active control condition that entailed lying supine on a warm waterbed in a dark and quiet room). Following Floatation-REST, subjects felt significantly more relaxed, less anxious, and less tired than after Bed-REST. Floatation-REST also induced significantly more pronounced ASC characterized by the dissolution of body boundaries and the distortion of subjective time. The loss of body boundaries mediated the loss of anxiety, revealing a novel mechanism by which Floatation-REST exerts its anxiolytic effect.

The role of perceptual processing in the oddball effect revealed by the Thatcher illusion

When a novel stimulus (oddball) appears after repeated presentation of an identical stimulus, the oddball is perceived to last longer than the repeated stimuli, a phenomenon known as the oddball effect. We investigated whether the perceptual or physical differences between the repeated and oddball stimuli are more important for the oddball effect. To manipulate the perceptual difference while keeping their physical visual features constant, we used the Thatcher illusion, in which an inversion of a face hinders recognition of distortion in its facial features. We found that the Thatcherized face presented after repeated presentation of an intact face induced a stronger oddball effect when the faces were upright than when they were inverted (Experiment 1). However, the difference in the oddball effect between face orientations was not observed when the intact face was presented as the oddball after repeated presentation of a Thatcherized face (Experiment 2). These results were replicated when participants performed both the intact-repeated and Thatcherized-repeated conditions in a single experiment (Experiment 3). Two control experiments confirmed that the repeated presentation of the preceding stimuli is necessary for the difference in duration distortion to occur (Experiments 4 and 5). The results suggest the considerable role of perceptual processing in the oddball effect. We discuss the discrepancy in the results between the intact-repeated and Thatcherized-repeated conditions in terms of predictive coding.

Mindfulness and time perception: A systematic integrative review

Several recent studies have explored the relationships between mindfulness and time perception, an area of research that has become increasingly popular in the last 10-15 years. In this article, we present a systematic integrative review of the evidence on this subject. We also integrate the field's findings into a conceptual framework which considers the multifaceted nature of both mindfulness, and time perception research. To identify the relevant literature, we searched the following databases using relevant keywords: PsycINFO; Medline; EBSCO Host Psychology and Behavioral Sciences Collection; and Web of Science. These searches were last performed on the 4th of May 2022, and additional hand searches were also conducted. To be included, articles had to be in English and contain original data about the potential relationship(s) between mindfulness and time perception. Articles which did not present usable data about the relationship(s) between the variables of interest were excluded. In total, 47 research articles were included in the review (combined sample size of ∼5800 participants). Risks of bias in the selected studies were evaluated using two separate assessment tools designed for this purpose. Through an integrative narrative synthesis, this article reviews how mindfulness may relate to time perception for various reference frames, and for various time perception measures and methods. It also provides new insights by exploring how a wide range of findings can be integrated into a coherent whole, in light of some relevant time perception models and mindfulness theories. Altogether, the reviewed data suggest the existence of complex and multifaceted relationships between mindfulness and time perception, highlighting the importance of considering many factors when planning research or interpreting data in this field. Limitations of the current review include the scarceness of data for certain categories of findings, and the relatively low prevalence of studies with a randomized controlled design in the source literature. This research was partly funded by a grant from the Natural Science and Engineering Research Council of Canada.

Detecting how time is subjectively perceived based on event-related potentials (ERPs): a machine learning approach

Background and objective: Time perception is essential for the precise performance of many of our activities and the coordination between different modalities. But it is distorted in many diseases and disorders. Event-related potentials (ERP) have long been used to understand better how the human brain perceives time, but machine learning methods have rarely been used to detect a person's time perception from his/her ERPs. Methods: In this study, EEG signals of the individuals were recorded while performing an auditory oddball time discrimination task. After features were extracted from ERPs, data balancing, and feature selection, machine learning models were used to distinguish between the oddball durations of 400 ms and 600 ms from standard durations of 500 ms. ERP results showed that the P3 evoked by the 600 ms oddball stimuli appeared about 200 ms later than that of the 400 ms oddball tones. Classification performance results indicated that support vector machine (SVM) outperformed K-nearest neighbors (KNN), Random Forest, and Logistic regression models. Results: The accuracy of SVM was 91.24, 92.96, and 89.9 for the three used labeling modes, respectively. Another important finding was that most features selected for classification were in the P3 component range, supporting the observed significant effect of duration on the P3. Although all N1, P2, N2, and P3 components contributed to detecting the desired durations. Conclusion: Therefore, results of this study suggest the P3 component as a potential candidate to detect sub-second periods in future researches on brain-computer interface (BCI) applications.

Modality-dependent distortion effects of temporal frequency on time perception

Time perception has been known to depend on the temporal frequency of the stimulus. Previously, the effect of temporal frequency modulation was assumed to be monotonically lengthening or shortening. However, this study shows that temporal frequency affects time perception in a non-monotonic and modality-dependent manner. Four experiments investigated the time distortion effects induced by modulation of temporal frequency across auditory and visual modalities. Critically, the temporal frequency was parametrically manipulated across four levels (steady stimulus, 10-, 20-, and 30/40-Hz intermittent auditory/visual stimulus). Experiment 1, 2, and 3 consistently showed that a 10-Hz auditory stimulus was perceived as shorter than a steady auditory stimulus. Meanwhile, as the temporal frequency increased, the perceived duration of the intermittent auditory stimulus was lengthened. A 40-Hz auditory stimulus was perceived as longer than a 10- Hz auditory stimulus, but did not differ significantly from a steady one. Experiment 4 showed that, for the visual modality, a 10-Hz visual stimulus was perceived as longer than a steady stimulus, and the perceived duration was lengthened as temporal frequency increased. This study demonstrated that within the scope of the temporal frequencies examined in this study, there were differential distortion effects observed across sensory modalities.

Time perception in film viewing: A modulation of scene's duration estimates as a function of film editing

Filmmakers and editors have empirically developed techniques to ensure the spatiotemporal continuity of a film's narration. In terms of time, editing techniques (e.g., elliptical, overlapping, or cut minimization) allow for the manipulation of the perceived duration of events as they unfold on screen. More specifically, a scene can be edited to be time compressed, expanded, or real-time in terms of its perceived duration. Despite the consistent application of these techniques in filmmaking, their perceptual outcomes have not been experimentally validated. Given that viewing a film is experienced as a precise simulation of the physical world, the use of cinematic material to examine aspects of time perception allows for experimentation with high ecological validity, while filmmakers gain more insight on how empirically developed techniques influence viewers' time percept. Here, we investigated how such time manipulation techniques of an action affect a scene's perceived duration. Specifically, we presented videos depicting different actions (e.g., a woman talking on the phone), edited according to the techniques applied for temporal manipulation and asked participants to make verbal estimations of the presented scenes' perceived durations. Analysis of data revealed that the duration of expanded scenes was significantly overestimated as compared to that of compressed and real-time scenes, as was the duration of real-time scenes as compared to that of compressed scenes. Therefore, our results validate the empirical techniques applied for the modulation of a scene's perceived duration. We also found interactions on time estimates of scene type and editing technique as a function of the characteristics and the action of the scene presented. Thus, these findings add to the discussion that the content and characteristics of a scene, along with the editing technique applied, can also modulate perceived duration. Our findings are discussed by considering current timing frameworks, as well as attentional saliency algorithms measuring the visual saliency of the presented stimuli.

Ebbinghaus, Müller-Lyer, and Ponzo: Three examples of bidirectional space-time interference

Previous studies have shown interference between illusory size and perceived duration. The present study replicated this space-time interference in three classic visual-spatial illusions, the Ebbinghaus, the Müller-Lyer, and the Ponzo illusion. The results showed bidirectional interference between illusory size and duration for all three illusions. That is, subjectively larger stimuli were judged to be presented longer, and stimuli that were presented longer were judged to be larger. Thus, cross-dimensional interference between illusory size and duration appears to be a robust phenomenon and to generalize across a wide range of visual size illusions. This space-time interference most likely arises at the memory level and supports the theoretical notion of a common representational metric for space and time.

Shift in excitation-inhibition balance underlies perceptual learning of temporal discrimination

Temporal perceptual learning (TPL) constitutes a unique and profound demonstration of neural plasticity within the brain. Our understanding for the neurometabolic changes associated with TPL on the other hand has been limited in part by the use of traditional fMRI approaches. Since plasticity in the visual cortex has been shown to underlie perceptual learning of visual information, we tested the hypothesis that TPL of an auditory interval involves a similar change in plasticity of the auditory pathway and if so, whether these changes take place in a lower-order sensory-specific brain area such as the primary auditory cortex (A1), or a higher-order modality-independent brain area such as the inferior parietal cortex (IPC). This distinction will inform us of the mechanisms underlying perceptual learning as well as the locus of change as it relates to TPL. In the present study, we took advantage of a new technique: proton magnetic resonance spectroscopy (MRS) in combination with psychophysical measures to provide the first evidence of changes in neurometabolic processing following 5 days of temporal discrimination training. We measured the (E)xcitation-to-(I)nhibition ratio as an index of learning in the right IPC and left A1 while participants learned an auditory two-tone discrimination task. During the first day of training, we found a significant task-related increase in functional E/I ratio within the IPC. While the A1 exhibited the opposite pattern of neurochemical activity, this relationship did not reach statistical significance. After timing performance has reached a plateau, there were no further changes to functional E/I. These findings support the hypothesis that improvements in temporal discrimination relies on neuroplastic changes in the IPC, but it is possible that both areas work synergistically to acquire a temporal interval.

Time perception in stimulant-dependent participants undergoing repetitive transcranial magnetic stimulation

BACKGROUND

The dopaminergic (DA) system is an important neural system for the modulation of time perception and the timing of motor actions. Dysregulation of the DA system is related to chronic use of stimulant drugs, which lead, among others, to executive dysfunctions. Little is known instead about the potential deficiencies in temporal processing of stimulant-dependent individuals. The present study aimed to investigate temporal processing using a time bisection task with different temporal intervals in chronic cocaine users undergoing repetitive transcranial magnetic stimulation (rTMS).

METHOD

Study 1: A time bisection task with short temporal intervals range (480/1920 ms) was administered to 18 cocaine use disorder (CocUD) patients and 20 healthy control before and after the intensive phase of rTMS treatment (5 days apart). Study 2: 22 CocUD participants and 23 control participants completed two temporal tasks (time bisection and time reproduction) with long temporal intervals range (1200/2640 ms) at baseline and immediately after the intensive phase of rTMS treatment.

RESULTS

Study 1: A shift in the psychometric function consistent with temporal overestimation in CocUD patients compared to controls was observed. However, no temporal impairment in CocUD patients at test session was found. Study 2: The analysis of temporal variability indices showed a significant difference between groups at baseline but not at Day 5 due to a significant difference between time points only in the CocUD group.

CONCLUSIONS

This study report a temporal overestimation in CocUD patients and a temporal variability reduction after an rTMS protocol in CocUD patients.

Embodying Time in the Brain: A Multi-Dimensional Neuroimaging Meta-Analysis of 95 Duration Processing Studies

Time is an omnipresent aspect of almost everything we experience internally or in the external world. The experience of time occurs through such an extensive set of contextual factors that, after decades of research, a unified understanding of its neural substrates is still elusive. In this study, following the recent best-practice guidelines, we conducted a coordinate-based meta-analysis of 95 carefully-selected neuroimaging papers of duration processing. We categorized the included papers into 14 classes of temporal features according to six categorical dimensions. Then, using the activation likelihood estimation (ALE) technique we investigated the convergent activation patterns of each class with a cluster-level family-wise error correction at p < 0.05. The regions most consistently activated across the various timing contexts were the pre-SMA and bilateral insula, consistent with an embodied theory of timing in which abstract representations of duration are rooted in sensorimotor and interoceptive experience, respectively. Moreover, class-specific patterns of activation could be roughly divided according to whether participants were timing auditory sequential stimuli, which additionally activated the dorsal striatum and SMA-proper, or visual single interval stimuli, which additionally activated the right middle frontal and inferior parietal cortices. We conclude that temporal cognition is so entangled with our everyday experience that timing stereotypically common combinations of stimulus characteristics reactivates the sensorimotor systems with which they were first experienced.

Time and visual-spatial illusions: Evidence for cross-dimensional interference between duration and illusory size

Time and space are intimately related to each other. Previous evidence has shown that stimulus size can affect perceived duration even when size differences are illusory. In the present study, we investigated the effect of visual-spatial illusions on duration judgments in a temporal reproduction paradigm. Specifically, we induced the Ebbinghaus illusion (Exp. 1) and the horizontal-vertical illusion (Exp. 2) during the encoding phase of the target interval or the reproduction phase. The results showed (a) that illusory size affects temporal processing similarly to the way physical size does, (b) that the effect is independent of whether the illusion appeared during encoding or reproduction, and (c) that the interference between size and temporal processing is bidirectional. These results suggest a rather late locus of size-time interference in the processing stream.

Mental association of time and valence

Five experiments investigated the association between time and valence. In the first experiment, participants classified temporal expressions (e.g., past, future) and positively or negatively connotated words (e.g., glorious, nasty) based on temporal reference or valence. They responded slower and made more errors in the mismatched condition (positive/past mapped to one hand, negative/future to the other) compared with the matched condition (positive/future to one hand, negative/past to the other hand). Experiment 2 confirmed the generalization of the match effect to nonspatial responses, while Experiment 3 found no reversal of this effect for left-handers. Overall, the results of the three experiments indicate a robust match effect, associating the past with negative valence and the future with positive valence. Experiment 4 involved rating the valence of time-related words, showing higher ratings for future-related words. Additionally, Experiment 5 employed latent semantic analysis and revealed that linguistic experiences are unlikely to be the source of this time-valence association. An interactive activation model offers a quantitative explanation of the match effect, potentially arising from a favorable perception of the future over the past.

The effects of increased mental workload of air traffic controllers on time perception: Behavioral and physiological evidence

Research has shown that timing is modulated by mental workload, making duration judgments a measure of cognitive demand, alongside subjective assessments, and physiological measurements. Yet, it is unclear whether such findings can be extended in less controlled setups. By employing air traffic controllers in a real aviation environment, we tested whether tasks with different levels of cognitive load can affect their timing behavior. Participants completed temporal production, verbal estimation, and passage of time judgments, while actively engaging in real flight control sessions. Subjective assessments of task demands, as well as physiological responses (cardiac and electrodermal activity) were also measured. Accuracy of the produced intervals was measured at two distinct phases of the flight (during low-load cruising vs. high-load landing) and under two different task load manipulations (controlling one vs. two helicopters and speaking in native vs. non-native language). Analysis of interval production accuracy showed that during the high-load landing phase significant overproductions were made, compared to the low-load cruising phase, and landing two helicopters led to greater overproductions compared to landing only one. The duration of the two-helicopter sessions was significantly overestimated compared to the single-helicopter ones, and the passage of time was felt significantly faster. Subjective assessments of workload were positively correlated with the temporal estimations and passage of time judgments, and skin responses were positively correlated with the produced intervals. Overall, our results are consistent with past research, suggesting that mental workload modulates time perception in complex, real-world environments, thus making timing behavior a reliable index of the workload changes.

How does it feel? Passage of time judgments in speeded RT performance

The relationship between duration perception and the feeling of time passing (passage of time) is not yet understood. In the present study, we assessed introspective reaction times (RT) and passage of time judgments in a speeded RT task. Task difficulty was manipulated in a numerical comparison task by numerical distance (distance from the number 45) and notation (digit vs. word). The results showed that both effects were reflected in introspective RTs, replicating previous results. Moreover, passage of time judgments showed a very similar pattern, with slower passage of time for more difficult comparisons. These results suggest that in the millisecond range judgments of duration and passage of time largely mirror each other when participants introspect about their own RT performance.

Transient attention does not alter the eccentricity effect in estimation of duration

Previous research investigating the influence of stimulus eccentricity on perceived duration showed an increasing duration underestimation with increasing eccentricity. Based on studies showing that precueing the stimulus location prolongs perceived duration, one might assume that this eccentricity effect is influenced by spatial attention. In the present study, we assessed the influence of transient covert attention on the eccentricity effect in duration estimation in two experiments, one online and one in a laboratory setting. In a duration estimation task, participants judged whether a comparison stimulus presented near or far from fixation with a varying duration was shorter or longer than a standard stimulus presented foveally with a constant duration. To manipulate transient covert attention, either a transient luminance cue was used (valid cue) to direct attention to the position of the subsequent peripheral comparison stimulus or all positions were marked by luminance (neutral cue). Results of both experiments yielded a greater underestimation of duration for the far than for the near stimulus, replicating the eccentricity effect. Although cueing was effective (i.e., shorter response latencies for validly cued stimuli), cueing did not alter the eccentricity effect on estimation of duration. This indicates that cueing leads to covert attentional shifts but does not account for the eccentricity effect in perceived duration.

Distinctive features of experiential time: Duration, speed and event density

William James's use of "time in passing" and "stream of thoughts" may be two sides of the same coin that emerge from the brain segmenting the continuous flow of information into discrete events. Herein, we investigated how the density of events affects two temporal experiences: the felt duration and speed of time. Using a temporal bisection task, participants classified seconds-long videos of naturalistic scenes as short or long (duration), or slow or fast (passage of time). Videos contained a varying number and type of events. We found that a large number of events lengthened subjective duration and accelerated the felt passage of time. Surprisingly, participants were also faster at estimating their felt passage of time compared to duration. The perception of duration scaled with duration and event density, whereas the felt passage of time scaled with the rate of change. Altogether, our results suggest that distinct mechanisms underlie these two experiential times.

Brief Report: A Randomized Controlled Trial of a Digital Working Memory Intervention for Preschoolers Displaying ADHD Symptoms

PURPOSE

This study aimed to investigate the effects of a self-paced digital working memory (WM) intervention on preschoolers with ADHD symptoms and explore the relation between WM and time perception (TP) through a randomized controlled trial.

METHOD

Fifty preschoolers between four-to-six years of age (M = 4.93 years) were randomly assigned to three groups: a WM training group (WM; n = 14), a social-emotional (SE) training active control group (n = 15), and a waitlist control group (n = 21). Both the WM and SE groups received fifteen 10-min self-paced digital training sessions over five consecutive weeks.

RESULTS

The digital WM training was effective in improving children's digit span performance compared to the waitlist control group only. Within-group comparisons across two time points indicated a near-significant improvement in numeration and trends of reduced ADHD symptoms and improved TP tasks in the WM group at the post-test, but between-group differences were not observed.

CONCLUSION

The study showed limited effects of the WM training on preschoolers displaying ADHD symptoms. However, the results implied an association between working memory and time perception that awaits further investigation.

What's next?: Time is subjectively dilated not only for 'oddball' events, but also for events immediately after oddballs

Our experience of time is strikingly plastic: Depending on contextual factors, the same objective duration can seem to fly by or drag on. Perhaps the most direct demonstration of such subjective time dilation is the oddball effect: when seeing identical objects appear one after another, followed by an "oddball" (e.g., a disc that suddenly grows in size, in a sequence of otherwise static discs), observers experience this oddball as having lasted longer than its nonoddball counterparts. Despite extensive work on this phenomenon, a surprisingly foundational question remains unasked: What actually gets dilated? Beyond the oddball, are the objects just before (or just after) the oddball also dilated? As in previous studies, observers viewed sequences of colored discs, one of which could be the oddball-and subsequently reproduced the oddball's duration. Unlike previous studies, however, there were also critical trials in which observers instead reproduced the duration of the disc immediately before or after the oddball. A clear pattern emerged: oddball-induced time dilation extended to the post-oddball disc, but not the pre-oddball disc. Whence this temporal asymmetry? We suggest that an oddball's sudden appearance may induce uncertainty about what will happen next, heightening attention until after the uncertainty is resolved.

The timing database: An open-access, live repository for interval timing studies

Interval timing refers to the ability to perceive and remember intervals in the seconds to minutes range. Our contemporary understanding of interval timing is derived from relatively small-scale, isolated studies that investigate a limited range of intervals with a small sample size, usually based on a single task. Consequently, the conclusions drawn from individual studies are not readily generalizable to other tasks, conditions, and task parameters. The current paper presents a live database that presents raw data from interval timing studies (currently composed of 68 datasets from eight different tasks incorporating various interval and temporal order judgments) with an online graphical user interface to easily select, compile, and download the data organized in a standard format. The Timing Database aims to promote and cultivate key and novel analyses of our timing ability by making published and future datasets accessible as open-source resources for the entire research community. In the current paper, we showcase the use of the database by testing various core ideas based on data compiled across studies (i.e., temporal accuracy, scalar property, location of the point of subjective equality, malleability of timing precision). The Timing Database will serve as the repository for interval timing studies through the submission of new datasets.

Feelings of responsibility and temporal binding: A comparison of two measures of the sense of agency

Temporal binding refers to a subjective shortening of the interval between an action and its perceptual consequences. Temporal binding has often been used by researchers to indirectly measure participants' sense of agency (SoA), or the subjective sense of causing something to happen. Other studies have proposed links between temporal binding and feelings of moral responsibility. The present study compared subjective interval estimates to feelings of responsibility in a between-subjects design (Exp 1) and a within-subjects design (Exp 2). Participants either estimated the interval between two events (two tones in the passive condition, or a keypress followed by a tone in active conditions) or rated their feeling of responsibility for the tone(s). Manipulations of participant involvement and choice impacted feelings of responsibility more than temporal estimates. Overall, the two dependent variables followed different patterns, suggesting subjective interval estimates may not be a reliable proxy for feelings of responsibility.

The effects of Vagal Nerve Stimulation on time perception in epilepsy patients

In this study, it was aimed to investigate the effects of switching off stimulation on time perception in patients with drug-resistant epilepsy who underwent Vagal Nerve Stimulation (VNS). In accordance with the literature, a cognitive battery of tests for motor timing and perceptual timing was utilized. Computerized time perception tests; Paced Motor Timing Test, Duration Discrimination Test, Temporal Reproduction Test, and Time Estimation Test were administered to the patients while VNS was on and off. A total of 14 patients who met the inclusion criteria of 23 VNS patients followed in the Epilepsy Outpatient Clinic were included in the study. In the Temporal Reproduction Test, for time durations of 1000 ms (ms), 2000 ms, 3000 ms, 4000 ms, and 5000 ms the comparison of reported time values between VNS on and VNS off yielded respective p values; p = 0.73, p = 0.03, p = 0.176, p = 0.418, p = 0,873. The reported time is thus significantly shorter only for 2000 ms when the VNS was on. Positive effect of VNS on attention, alertness and focusing are expected to cause acceleration of the internal clock resulting in perceiving time running slower than actual. In our study, it was concluded that the internal clock runs faster when the VNS is on, and time is perceived as running slower than it actually is. This result can also be accepted as an indirect indicator of increased attention in the period when VNS is on.

Influences of temporal order in temporal reproduction

Despite the crucial role of complex temporal sequences, such as speech and music, in our everyday lives, our ability to acquire and reproduce these patterns is prone to various contextual biases. In this study, we examined how the temporal order of auditory sequences affects temporal reproduction. Participants were asked to reproduce accelerating, decelerating or random sequences, each consisting of four intervals, by tapping their fingers. Our results showed that the reproduction and the reproduction variability were influenced by the sequential structure and interval orders. The mean reproduced interval was assimilated by the first interval of the sequence, with the lowest mean for decelerating and the highest for accelerating sequences. Additionally, the central tendency bias was affected by the volatility and the last interval of the sequence, resulting in a stronger central tendency in the random and decelerating sequences than the accelerating sequence. Using Bayesian integration between the ensemble mean of the sequence and individual durations and considering the perceptual uncertainty associated with the sequential structure and position, we were able to accurately predict the behavioral results. The findings highlight the critical role of the temporal order of a sequence in temporal pattern reproduction, with the first interval exerting greater influence on mean reproduction and the volatility and the last interval contributing to the perceptual uncertainty of individual intervals and the central tendency bias.

The effect of modality and order presentation of emotional stimuli on time perception

Despite human accuracy in perceiving time, many factors can modulate the subjective experience of time. For example, it is widely reported that emotion can expand or shrink our perception of time and that temporal intervals are perceived as longer when marked by auditory stimuli than by visual stimuli. In the present study, we aimed at investigating whether the influence of emotion on time perception can be altered by the order in which emotional stimuli are presented and the sensory modality in which they are presented. Participants were asked to complete a time bisection task in which emotional stimuli were presented either acoustically or visually, and either before or after interval to be estimated. We observed a main effect of modality (longer perceived duration and lower variability in the auditory than in the visual modality) as well as a main effect of emotion (temporal overestimation for negative stimuli compared to neutral). Importantly, the effects of modality and emotion interacted with the order of presentation of the emotional stimuli. In the visual condition, when emotional stimuli were presented after the temporal intervals, participants overestimated time, but no differences between negative and neutral stimuli were observed when emotional stimuli were presented first. In the auditory condition, no significant effect of emotion on perceived duration was found. Results suggest that negative emotions affect our perception of durations acting at the decision-making stage rather than at the pacemaker one. No effect on time perception was observed for emotional auditory stimuli.

Temporal perception in closed-skill sports: An experimental study on expert swimmers and runners

The cognitive benefits of closed-skill sports practice have so far been scantily investigated. Here, we thus focused on the potential impact of swimming and running - two sports that highly rely on a precise control of timing - on time processing. To investigate the impact of these closed-skill sports on time perception and estimation, three groups of participants (for a total of eighty-four young adults) took part in the present study: expert swimmers, expert runners, and non-athletes. The ability to process temporal information in the milliseconds and seconds range was assessed through a time reproduction and a finger-tapping tasks, while a motor imagery paradigm was adopted to assess temporal estimation of sport performance in a wider interval range. We also employed the Vividness of Movement Imagery Questionnaire to assess the individual's ability of motor imagery. Results showed that closed-skill sports, specifically time-related disciplines, enhance motor imagery and time perception abilities. Swimmers were more accurate and consistent in perceiving time when compared to runners, probably thanks to the sensory muffled environment that leads these athletes to be more focused on the perception of their internal rhythm.

Can't catch the beat: Failure to find simple repetition effects in three types of temporal judgements

More experience results in better performance, usually. In most tasks, the more chances to learn we have, the better we are at it. This does not always appear to be the case in time perception however. In the current article, we use three different methods to investigate the role of the number of standard example durations presented on performance on three timing tasks: rhythm continuation, deviance detection, and final stimulus duration judgement. In Experiments 1a and 1b, rhythms were produced with the same accuracy whether one, two, three, or four examples of the critical duration were presented. In Experiment 2, participants were required to judge which of four stimuli had a different duration from the other three. This judgement did not depend on which of the four stimuli was the deviant one. In Experiments 3a and 3b, participants were just as accurate at judging the duration of a final stimulus in comparison to the prior stimuli regardless of the number of standards presented prior to the final stimulus. In summary, we never found any systematic effect of the number of standards presented on performance on any of the three timing tasks. In the discussion, we briefly relate these findings to three theories of time perception.

Time processing in neurological and psychiatric conditions

A central question in understanding cognition and pathology-related cognitive changes is how we process time. However, time processing difficulties across several neurological and psychiatric conditions remain seldom investigated. The aim of this review is to develop a unifying taxonomy of time processing, and a neuropsychological perspective on temporal difficulties. Four main temporal judgments are discussed: duration processing, simultaneity and synchrony, passage of time, and mental time travel. We present an integrated theoretical framework of timing difficulties across psychiatric and neurological conditions based on selected patient populations. This framework provides new mechanistic insights on both (a) the processes involved in each temporal judgement, and (b) temporal difficulties across pathologies. By identifying underlying transdiagnostic time-processing mechanisms, this framework opens fruitful avenues for future research.

Face Age is Mapped Into Three-Dimensional Space

People can represent temporal stimuli (e.g., pictures depicting past and future events) as spatially connoted dimensions arranged along the three main axes (horizontal, sagittal, and vertical). For example, past and future events are generally represented, from the perspective of the individuals, as being placed behind and in front of them, respectively. Here, we report that such a 3D representation can also emerge for facial stimuli of different ages. In three experiments, participants classified a central target face, representing an individual at different age stages, as younger or older than the reference face of 40 years. Manual responses were provided with two keys placed along the horizontal axis (Experiment 1), the sagittal axis (Experiment 2), and the vertical axis (Experiment 3). The results indicated that the younger faces were represented on the left/back/top side of the space, whereas the older faces were represented on the right/forward/bottom side of the space. Furthermore, in all experiments, the latencies decreased with the absolute difference between the age of the target face and that of the reference face (i.e., a distance effect). Overall, this work suggests that the spatial representation of time includes social features of the human face.

Dynamics of retrospective timing: A big data approach

Most interval timing research has focused on prospective timing tasks, in which participants are explicitly asked to pay attention to time as they are tested over multiple trials. Our current understanding of interval timing primarily relies on prospective timing. However, most real-life temporal judgments are made without knowing beforehand that the durations of events will need to be estimated (i.e., retrospective timing). The current study investigated the retrospective timing performance of ~24,500 participants with a wide range of intervals (5-90 min). Participants were asked to judge how long it took them to complete a set of questionnaires that were filled out at the participants' own pace. Participants overestimated and underestimated durations shorter and longer than 15 min, respectively. They were most accurate at estimating 15-min long events. The between-subject variability in duration estimates decreased exponentially as a function of time, reaching the lower asymptote after 30 min. Finally, a considerable proportion of participants exhibited whole number bias by rounding their duration estimates to the multiples of 5 min. Our results provide evidence for systematic biases in retrospective temporal judgments, and show that variability in retrospective timing is relatively higher for shorter durations (e.g., < 30 min). The primary findings gathered from our dataset were replicated based on the secondary analyses of another dataset (Blursday). The current study constitutes the most comprehensive study of retrospective timing regarding the range of durations and sample size tested.

Validating virtual reality for time perception research: Virtual reality changes expectations about the duration of physical processes, but not the sense of time

Immersive virtual reality (VR) provides a versatile method for investigating human time perception, because it allows the manipulation and control of relevant variables (e.g., the speed of environmental changes) that cannot be modified in the real world. However, an important premise for interpreting the results of VR studies, namely that the method itself does not affect time perception, has received little attention. Here we tested this assumption by comparing timing performance in a real environment and a VR scenario. Participants performed two timing tasks, requiring the production of intervals defined either by numerical values ("eight seconds") or by a physical process ("the time it takes for a bottle to run out when turned over"). We found that the experience of immersive VR exclusively altered judgments about the duration of physical processes, whereas judgments about the duration of abstract time units were unaffected. These results demonstrate that effects of VR on timing performance are not driven by changes in time perception itself, but rather by altered expectations regarding the duration of physical processes. The present study validates the use of VR in time perception research and strengthens the interpretation of changed timing behaviour induced by manipulations within VR.

Probing the processing of facial expressions in monkeys via time perception and eye tracking

Accurately recognizing facial expressions is essential for effective social interactions. Non-human primates (NHPs) are widely used in the study of the neural mechanisms underpinning facial expression processing, yet it remains unclear how well monkeys can recognize the facial expressions of other species such as humans. In this study, we systematically investigated how monkeys process the facial expressions of conspecifics and humans using eye-tracking technology and sophisticated behavioral tasks, namely the temporal discrimination task (TDT) and face scan task (FST). We found that monkeys showed prolonged subjective time perception in response to Negative facial expressions in monkeys while showing longer reaction time to Negative facial expressions in humans. Monkey faces also reliably induced divergent pupil contraction in response to different expressions, while human faces and scrambled monkey faces did not. Furthermore, viewing patterns in the FST indicated that monkeys only showed bias toward emotional expressions upon observing monkey faces. Finally, masking the eye region marginally decreased the viewing duration for monkey faces but not for human faces. By probing facial expression processing in monkeys, our study demonstrates that monkeys are more sensitive to the facial expressions of conspecifics than those of humans, thus shedding new light on inter-species communication through facial expressions between NHPs and humans.

Psychophysiological stress influences temporal accuracy

Distortions of duration perception are often observed in response to highly arousing stimuli, but the exact mechanisms that evoke these variations are still under debate. Here, we investigate the effect of induced physiological arousal on time perception. Thirty-eight university students (22.89 ± 2.5; 28 females) were tested with spontaneous finger-tapping tasks and a time bisection task (with stimuli between 300 and 900 ms). Before the time bisection task, half of the participants (STRESS group) performed a stress-inducing task, i.e., the Paced Auditory Serial Addition Test (PASAT), whereas the other participants (CONTROL group) performed a control task, the Paced Auditory Number Reading Task (PANRAT). The PASAT induced a greater heart rate, but not electrodermal, increase, as well as a more unpleasant and arousing state compared to the PANRAT. Moreover, although the two groups presented a similar performance at the finger-tapping tasks, participants in the STRESS group showed better temporal performance at the time bisection task (i.e., lower constant error) than the controls. These results indicate that psychophysiological stress may alter the subsequent perception of time.

Perceived timing of postural instability onset

BACKGROUND

This study investigates the perceived onset of postural instability, a critical aspect of balance. Prior research using Temporal Order Judgment (TOJ) tasks revealed that postural perturbations must occur significantly earlier than an auditory reference stimulus for individuals to perceive them as simultaneous. However, there are methodological concerns with this previous work, particularly an unbalanced stimulus onset asynchrony (SOA) distribution.

RESEARCH QUESTION

Does the point of subjective simultaneity (PSS) between postural perturbation onset and an auditory reference stimulus differ between SOA distributions unequally (distribution 1) and equally (distribution 2) distributed around true simultaneity (0 ms)?

METHODS

A repeated measures design was employed, presenting two different SOA distributions to 10 participants using a TOJ task during both distribution 1 (88 trials) and distribution 2 (72 trials) SOA distributions. Paired t-tests were used to determine if there was a significant difference between the PSS of distribution 1 and 2. One-sample t-tests were also performed on the PSS values of both conditions in comparison to 0 ms (defined as true simultaneity) to determine if perceptual responses were delayed.

RESULTS

Distribution 1 led to a perceived delay of postural instability onset by 20.34 ms, while distribution 2 resulted in a perceived delay of the auditory stimulus of 3.52 ms. However, neither condition was significantly different from each other nor from true simultaneity.

SIGNIFICANCE

These findings suggest that the perception of postural instability onset is not slow, contrary to previous beliefs, and emphasize the importance of controlling methodological parameters when examining sensory cues. This understanding will help inform falls prevention strategies.

Lower loss rate of serotonergically modulated neuronal accumulator for time in patients with major depressive disorder

Major depressive disorder (MDD) is characterized by dramatic and persistent worsening of mood, as well as a subjective feeling of time slowing. However, experimental data on time perception are inconsistent. As serotonergic dysfunction implicated in MDD etiology, we aim to examine time perception in MDD through the framework of lossy temporal integration model, previously also related to serotonergic transmission. Thirty-one patients with recurrent depressive disorder in partial remission and thirty control participants, without a history of psychiatric and neurological disorders, performed duration discrimination of visual stimuli (duration ranges from 3.2 to 6.4 s) and subjective minute production tasks. To infer about central serotonergic transmission, an electroencephalogram in response to the 1000 Hz tone of different intensity (50, 60, 70 and 80 dB SPL) was recorded. Patients with MDD shorten the past durations in the duration discrimination task significantly less than controls, thus being more objective. No difference in the subjective minute production was recorded. Patients with MDD have also exhibited larger auditory evoked potentials in response to the tones of high intensity (70 and 80 dB SPL) when compared with the controls. This resulted in a steeper slope of auditory evoked potentials by intensity function. These converging findings suggest a lower loss rate of neuronal temporal accumulator modulated by serotonergic transmission in patients with MDD.

Electrophysiological signatures of temporal context in the bisection task

Despite having relatively accurate timing, subjective time can be influenced by various contexts, such as stimulus spacing and sample frequency. Several electroencephalographic (EEG) components have been associated with timing, including the contingent negative variation (CNV), offset P2, and late positive component of timing (LPCt). However, the specific role of these components in the contextual modulation of perceived time remains unclear. In this study, we conducted two temporal bisection experiments to investigate this issue. Participants had to judge whether a test duration was close to a short or long standard. Unbeknownst to them, we manipulated the stimulus spacing (Experiment 1) and sample frequency (Experiment 2) to create short and long contexts while maintaining consistent test ranges and standards across different sessions. The results revealed that the bisection threshold shifted towards the ensemble mean, and both CNV and LPCt were sensitive to context modulation. In the short context, the CNV exhibited an increased climbing rate compared to the long context, whereas the LPCt displayed reduced amplitude and latency. These findings suggest that the CNV represents an expectancy wave preceding a temporal decision process, while the LPCt reflects the decision-making process itself, with both components influenced by the temporal context.

The effect of visually filled reproductions on the reproduced durations of auditory intervals

The present study examined how the perception of time is affected by the presence of a visual stimulus during the reproduction phase of an online time reproduction task. Participants were instructed to reproduce the durations of speed-altered speech snippets with either a picture or a blank screen presented during the reproduction phase. Results showed that fast speeches were reproduced as longer than slow ones, while the reproduced durations of short speeches were closer to the actual durations than were the long speeches. In addition, longer reproduced durations were observed in trials with a picture than in trials with a blank screen. These results provide clear evidence that postencoding information can influence the reproduction of previously encoded temporal intervals and are discussed in the context of attention allocation and its possible influence on an internal clock mechanism. Also, the study provides evidence that online testing is reliable for assessing biases in time perception, at least with time reproduction tasks.

The effect of emotion intensity on time perception: a study with transcranial random noise stimulation

Emotional facial expressions provide cues for social interactions and emotional events can distort our sense of time. The present study investigates the effect of facial emotional stimuli of anger and sadness on time perception. Moreover, to investigate the causal role of the orbitofrontal cortex (OFC) in emotional recognition, we employed transcranial random noise stimulation (tRNS) over OFC and tested the effect on participants' emotional recognition as well as on time processing. Participants performed a timing task in which they were asked to categorize as "short" or "long" temporal intervals marked by images of people expressing anger, sad or neutral emotional facial expressions. In addition, they were asked to judge if the image presented was of a person expressing anger or sadness. The visual stimuli were facial emotional stimuli indicating anger or sadness with different degrees of intensity at high (80%), medium (60%) and low (40%) intensity, along with neutral emotional face stimuli. In the emotional recognition task, results showed that participants were faster and more accurate when emotional intensity was higher. Moreover, tRNS over OFC interfered with emotion recognition, which is in line with its proposed role in emotion recognition. In the timing task, participants overestimated the duration of angry facial expressions, although neither emotional intensity not OFC stimulation significantly modulated this effect. Conversely, as the emotional intensity increased, participants exhibited a greater tendency to overestimate the duration of sad faces in the sham condition. However, this tendency disappeared with tRNS. Taken together, our results are partially consistent with previous findings showing an overestimation effect of emotionally arousing stimuli, revealing the involvement of OFC in emotional distortions of time, which needs further investigation.

Neural substrates of top-down processing during perceptual duration-based timing and beat-based timing

Temporal context is a crucial factor in timing. Previous studies have revealed that the timing of regular stimuli, such as isochronous beats or rhythmic sequences (termed beat-based timing), activated the basal ganglia, whereas the timing of single intervals or irregular stimuli (termed duration-based timing) activated the cerebellum. We conducted a functional magnetic resonance imaging (fMRI) experiment to determine whether top-down processing of perceptual duration-based and beat-based timings affected brain activation patterns. Our participants listened to auditory sequences containing both single intervals and isochronous beats and judged either the duration of the intervals or the tempo of the beats. Whole-brain analysis revealed that both duration judgments and tempo judgments activated similar areas, including the basal ganglia and cerebellum, with no significant difference in the activated regions between the two conditions. In addition, an analysis of the regions of interest revealed no significant differences between the activation levels measured for the two tasks in the basal ganglia as well as the cerebellum. These results suggested that a set of common brain areas were involved in top-down processing of both duration judgments and tempo judgments. Our findings indicate that perceptual duration-based timing and beat-based timing are driven by stimulus regularity irrespective of top-down processing.

Increased relaxation, less boredom, and a faster passage of time during a period of silence in the forest

INTRODUCTION

There is growing evidence of the beneficial effects of exposure to nature on health and well-being. Time spent in nature can decrease stress, anxiety, depression, and improve mood. In the present study, we compared the experience of a short period of silence in the natural environment of a forest with the same amount of silence in a seminar room.

METHODS

We applied an intra-subject design with two 6:30-min sessions of silence in two different environments (forest, seminar room). The participants (n=41) were assigned to four groups. Two groups started with the indoor condition and two groups with the outdoor condition. After 1 week, the two groups were exposed to the other condition. Participants filled out personality-trait scales on meaning in life and belief in oneness with the world, as well as state scales assessing emotional reactions, relaxation, boredom, and the subjective sense of self, time, and space.

RESULTS

Participants felt significantly more relaxed and less bored in the forest compared to indoors. They experienced time less intensely, judging it to pass faster and to last shorter in the forest. Regarding trait variables, the higher the search for meaning, the higher oneness beliefs in participants. The higher oneness beliefs, the more positive participants felt during silence in the forest.

DISCUSSION

Interest in nature-assisted therapy is increasing in the healthcare sector. Exposure to silence in the natural setting of a forest could prove to be an effective complement to interventions applied in nature-assisted therapy, such as forest therapy.

Age Differences in Self-Continuity in Germany and the United States: The Role of Temporal Direction, Temporal Distance, and Demographics

OBJECTIVES

Previous research suggests that self-continuity is higher in older ages, especially for more distant intervals. This study extends prior work by examining age and temporal patterns of self-continuity in 2 adult life-span samples from Germany and the United States.

METHODS

German data (n = 1,656, aged 18-93) were drawn from the German Socioeconomic Panel. U.S. data (n = 230, aged 18-87) were collected through a survey research firm. Preregistered multilevel analyses examined the roles of age, temporal direction (past/future), and temporal distance (1/5/10 years), and explored the role of demographic covariates.

RESULTS

In both data sets, self-continuity was higher in older ages and decreased with distance from the present, especially for the past. Interaction effects among age, temporal distance, and temporal directions were complex and varied across samples. Self-continuity was higher among married and more educated German participants and more affluent U.S. participants, but age differences remained robust when including demographic covariates.

DISCUSSION

Findings replicate prior evidence for age-related increments in self-continuity but suggest that patterns vary by temporal distance and direction and may be sensitive to contextual factors.

What came before: Assimilation effects in the categorization of time intervals

Assimilation is the process by which one judgment tends to approach some aspect of another stimulus or judgment. This effect has been known for over half a century in various domains such as the judgment of weight or sound intensity. However, the assimilation of judgments of durations have been relatively unexplored. In the current article, we present the results of five experiments in which participant s were required to judge the duration of a visual stimulus on each trial. In each experiment, we manipulated the pattern of durations they experienced in order to systematically separate the effects of the objective and subjective duration of stimuli on subsequent judgments. We found that duration judgments were primarily driven by prior judgments, with little, if any, effect of the prior objective stimulus duration. This is in contrast to the findings previously reported in regards to non-temporal judgments. We propose two mechanist explanations of this effect; a representational account in which judgments represent the speed of an underlying pacemaker, and an assimilation account in which judgment is based in prior experience. We further discuss results in terms of predictive coding, in which the previous rating is representative of a prior expectation, which is modified by current experience.

Insights into the perceptual moment theory: Experimental evidence from simultaneity judgment

The perception appears to flow in a continuous pattern but evidence suggest that perception may involve discrete temporal sampling of peripheral cues. Stroud's perceptual moment theory proposes that perception occurs in discrete moments; however, more experimental evidence is required to support this theory. The present study characterized the decision function for asynchrony detection using variable stimulus-onset asynchronies (SOAs). Fourteen healthy volunteers (twelve males and two females), ages 21.5 ± 3.8 years (mean ± SD) participated in the study. A microcontroller was used to randomly present 280 events of paired stimuli (two red LEDs) with varying SOAs from -65 to 65 ms in steps of 5 ms. Participants were asked to press the "L" or "R" response key based on whether the left or right LED lit up first and to press the "S" key if they could not perceive the order. Asynchrony detection does not exhibit a fixed threshold value; instead, its decision function shows a monotonic increase with increasing SOAs. The asynchrony detection was 50% at an SOA of 27.8 ± 1.7 ms (mean ± SE). The curve plateaued off near 100% at SOA of 57.2 ms, which may correspond to the duration of one perceptual moment for visual perception. Data from a separate group of ten volunteers was used to validate the results. Results indicate that perception is temporally discretized rather than continuous, and the estimated duration of one perceptual moment is around 57.2 ms. This simple experiment gives objective evidence for Stroud's perceptual moment theory.

Hand movements influence the perception of time in a prediction motion task

Human perception of time is far from accurate and is subject to distortions. Previous research has demonstrated that any manipulation that distorts the perceived velocity of visible moving objects may shift prediction motion (PM) performance during occlusion. However, it is not clear whether motor action has the same influence during occlusion in the PM task. This work evaluated the influence of action on PM performance in two experiments. In both cases, participants performed an interruption paradigm, evaluating if an occluded object had reappeared earlier or later than expected. This task was done simultaneously with a motor action. In Experiment 1, we compared the PM performance according to the timing of the action made while the object was still visible or occluded. In Experiment 2, participants had to perform (or not) a motor action if the target was green (or red). In both experiments, our results showed that the duration of the object's occlusion was underestimated in the specific case of acting during the occlusion period. These results suggest that action and temporal perception share similar neural bases. Future research is needed to confirm this hypothesis.

The contribution of the supplementary motor area to explicit and implicit timing: A high-definition transcranial Random Noise Stimulation (HD-tRNS) study

It is becoming increasingly accepted that timing tasks, and underlying temporal processes, can be partitioned on the basis of whether they require an explicit or implicit temporal judgement. Most neuroimaging studies of timing associated explicit timing tasks with activation of the supplementary motor area (SMA). However, transcranial magnetic stimulation (TMS) studies perturbing SMA functioning across explicit timing tasks have generally reported null effects, thus failing to causally link SMA to explicit timing. The present study probed the involvement of SMA in both explicit and implicit timing tasks within a single experiment and using High-Definition transcranial Random Noise Stimulation (HD-tRNS), a previously less used technique in studies of the SMA. Participants performed two tasks that comprised the same stimulus presentation but differed in the received task instructions, which might or might not require explicit temporal judgments. Results showed a significant HD-tRNS-induced shift of perceived durations (i.e., overestimation) in the explicit timing task, whereas there was no modulation of implicit timing by HD-tRNS. Overall, these results provide initial non-invasive brain stimulation evidence on the contribution of the SMA to explicit and implicit timing tasks.

The neural representation of time distributed across multiple brain regions differs between implicit and explicit time demands

Animals appear to possess an internal timer during action, based on the passage of time. However, the neural underpinnings of the perception of time, ranging from seconds to minutes, remain unclear. Herein, we considered the neural representation of time based on mounting evidence on the neural correlates of time perception. The passage of time in the brain is represented by two types of neural encoding as follows: (i) the modulation of firing rates in single neurons and (ii) the sequential activity in neural ensembles. Time-dependent neural activity reflects the relative time rather than the absolute time, similar to a clock. They emerge in multiple regions, including the hippocampus, medial and lateral entorhinal cortices, medial prefrontal cortex, and dorsal striatum. Moreover, they involve different brain regions, depending on an implicit or explicit event duration. Thus, the two types of internal timers distributed across multiple brain regions simultaneously engage in time perception, in response to implicit or explicit time demands.

Stimulus (dis)similarity can modify the effect of a task-irrelevant sandwiching stimulus on the perceived duration of brief visual stimuli

The perceived duration of a target visual stimulus is shorter when a brief non-target visual stimulus precedes and trails the target than when it appears alone. This time compression requires spatiotemporal proximity of the target and non-target stimuli, which is one of the perceptual grouping rules. The present study examined whether and how another grouping rule, stimulus (dis)similarity, modulated this effect. In Experiment 1, time compression occurred only when the preceding and trailing stimuli (black-white checkerboard) were dissimilar from the target (unfilled round or triangle) with spatiotemporal proximity. In contrast, it was reduced when the preceding or trailing stimuli (filled rounds or triangles) were similar to the target. Experiment 2 revealed time compression with dissimilar stimuli, independent of the intensity or saliency of the target and non-target stimuli. Experiment 3 replicated the findings of Experiment 1 by manipulating the luminance similarity between target and non-target stimuli. Furthermore, time dilation occurred when the non-target stimuli were indistinguishable from the target stimuli. These results indicate that stimulus dissimilarity with spatiotemporal proximity induces time compression, whereas stimulus similarity with spatiotemporal proximity does not. These findings were discussed in relation to the neural readout model.

Effects of ketamine optical isomers, fluoxetine and naloxone on timing in differential reinforcement of low-rate response (DRL) 72-s task in rats

(S)-ketamine-induced rapid-acting antidepressant effects have revolutionized the pharmacotherapy of major depression; however, this medication also produces psychotomimetic effects such as timing distortion. While (R)-ketamine produces fewer dissociative effects, its antidepressant actions are less studied. Depression is associated with time overestimation (i.e., subjectively, time passes slowly). Our recent report suggests that while (S)-ketamine induces an opposite effect, i.e., time underestimation, the (R)-isomer does not affect timing. It has been suggested that opioid receptors are involved in the antidepressant effect of ketamine. In the present study we tested (R)- and (S)-ketamine, and fluoxetine as a positive control in the differential-reinforcement-of-low-rate (DRL) 72-s schedule of reinforcement in male rats following naloxone pretreatment. DRL classic metrics as well as peak deviation analyses served to determine antidepressant-like actions and those associated with timing. We report antidepressant-like effects of (S)-ketamine (30-60 mg/kg) that resemble fluoxetine's (2.5-10 mg/kg), as both compounds increased reinforcement rate and peak location (suggesting increased performance), reduced premature responses (suggesting time underestimation) and decreased Weber's fraction (suggesting increased timing precision). (R)-ketamine (30, but not 60 mg/kg) increased only the reinforcement rate and peak location but did not affect timing. Only fluoxetine decreased burst responses, suggesting decreased impulsivity. Naloxone pretreatment did not block ketamine enantiomers' actions, but unexpectedly, increased fluoxetine' performance. Thus, while all three medications produced antidepressant-like effects in DRL 72-s, fluoxetine- and (S)- but not (R)- ketamine-induced time underestimation (the subject experiences the time as passing quickly). The potentiation of DRL performance of fluoxetine by naloxone was unexpected and warrants clinical studies.