The feeling of the passage of time against the time of the external clock.

When people say that time is passing faster or slower, they are referring to the clock time. What exactly is the role of this reference to clock time in the awareness of the passage of time? Three experiments were conducted to examine this question. In Experiment 1, participants performed an easy and a difficult task in a condition with or without an external clock. In Experiment 2, the external clock was introduced after several trials of the easy task performed by the same participants. In Experiment 3, the speed of the clock hands was manipulated. Eye movements towards the clock were recorded by an eye tracker. The results showed that time was judged to pass faster with the external clock, thus reducing the distortion of the sense of time. Indeed, participants noticed that time passed faster than they initially thought. However, our results also showed that this was an occasional and short-lived adjustment of subjective time to objective time, with a greater acceleration in the presence of the fast clock. Indeed, the clock quickly lost its effect after a few trials, the feeling of the passage remaining based on the emotion felt, i.e., the boredom felt in the easy task. Our experiments thus showed that the feeling of the passage of time is primarily grounded in the emotional affect experienced (Embodiment), and that knowledge of clock time had only a small and transient corrective effect.

What factors underlie our experience of the passage of time? Theoretical consequences.

The aim of this study was to examine the factors that explain variations in the conscious experience of time. The level of difficulty of the task, emotional valence and duration of stimuli were tested in three different experiments with two ranges of durations, one of seconds and the other one of minutes. The results showed that the passage of time was judged faster with durations in the seconds than in the minutes range. However, for all duration values, each change in the features of the task produced changes in the judgment of the passage of time. The subjective feeling of an acceleration of the passage of time, therefore, increased linearly with the increase in the level of difficulty of the task and with the positive valence of the emotional stimuli. It also varied linearly with the length of real time, increasing in the same proportion as the decrease in stimulus duration, regardless of the associated range (seconds or minutes). Our theory is that the judgment of the passage of time might be a generic way of describing the most salient internal or external contextual changes experienced.

Asymmetry in updating long-term memory for time.

The present study evaluates the updating of long-term memory for duration. After learning a temporal discrimination associating one lever with a standard duration (4 sec) and another lever with both a shorter (1-sec) and a longer (16-sec) duration, rats underwent a single session for learning a new standard duration. The temporal generalization gradient obtained 24 h later showed a modification in long-term memory for durations longer than the standard but only when the new duration was longer than the one initially learned. The effect was confirmed for another set of durations (0.5-2-8 sec). Our study demonstrates asymmetry in updating long-term memory for time.

Simultaneous time processing in children and adults: When attention predicts temporal interference effects.

Children from 5 to 8 years of age, as well as adults, performed a temporal reproduction task in both a solo-timing condition and a multi-timing condition, with different durations presented simultaneously. In the multi-timing condition, all durations were processed because the participants did not know in advance which stimulus needed to be judged. In a first experiment, two or three durations were presented with a synchrony of their onset. In a second experiment, two durations were presented simultaneously with asynchrony of their offset, different lengths of the concurrent duration, and different presentation orders. In addition, the participants' cognitive abilities in terms of selective attention, as well as short-term and working memory, were assessed with different neuropsychological tests. The results of both experiments showed that children and adults alike were able to process multiple durations simultaneously. However, the simultaneous presentation of different durations generated a temporal interference effect in children and adults, resulting in longer and more variable time estimates. This temporal interference effect was nevertheless higher in children due to their limited attention capacities. Therefore, a developmental improvement in the ability to process different durations simultaneously is related to the cognitive development of attention capacities.

Learning versus reasoning to use tools in children.

Tool behavior might be based on two strategies associated with specific cognitive mechanisms: cued-learning and technical-reasoning strategies. We aimed to explore whether these strategies coexist in young children and whether they are manifest differently through development. We presented 216 3- to 9-year-olds with a vertical maze task consisting in moving a ball from the top to the bottom of a maze. Two tool-use/mechanical actions were possible: rotating action and sliding action. Three conditions were tested, each focused on a different strategy. In the Opaque-Cue condition (cued-learning strategy), children could not see the mechanical action of each tool. Nevertheless, a cue was provided according to the tool needed to solve the problem. In the Transparent-No Cue condition (technical-reasoning strategy), no cue was presented. However, children could see the mechanical actions associated with each tool. In the Transparent-Cue condition (cued-learning and/or technical-reasoning strategies) children saw both the mechanical actions and the cues. Results indicated that the Opaque-Cue and Transparent-Cue conditions were easier than the Transparent-No-Cue condition in all children. These findings stress that children can use either cued learning or technical reasoning to use tools, according to the available information. The behavioral pattern observed in the Transparent-Cue condition suggests that children might be inclined to use technical reasoning even when the task can be solved through cued learning.

The beneficial effect of synchronized action on motor and perceptual timing in children.

We examined the role of action in motor and perceptual timing across development. Adults and children aged 5 or 8 years old learned the duration of a rhythmic interval with or without concurrent action. We compared the effects of sensorimotor versus visual learning on subsequent timing behaviour in three different tasks: rhythm reproduction (Experiment 1), rhythm discrimination (Experiment 2) and interval discrimination (Experiment 3). Sensorimotor learning consisted of sensorimotor synchronization (tapping) to an isochronous visual rhythmic stimulus (ISI = 800 ms), whereas visual learning consisted of simply observing this rhythmic stimulus. Results confirmed our hypothesis that synchronized action during learning systematically benefitted subsequent timing performance, particularly for younger children. Action-related improvements in accuracy were observed for both motor and perceptual timing in 5 years olds and for perceptual timing in the two older age groups. Benefits on perceptual timing tasks indicate that action shapes the cognitive representation of interval duration. Moreover, correlations with neuropsychological scores indicated that while timing performance in the visual learning condition depended on motor and memory capacity, sensorimotor learning facilitated an accurate representation of time independently of individual differences in motor and memory skill. Overall, our findings support the idea that action helps children to construct an independent and flexible representation of time, which leads to coupled sensorimotor coding for action and time.

Differences in modal distortion in time perception due to working memory capacity: a response with a developmental study in children and adults.

This study tested the modality effect on time judgment in a bisection task in children and adults when auditory and visual stimuli were presented in the same session. Cognitive capacities of children and adults were assessed with different neuropsychological tests. The results showed a modality effect, with the auditory stimuli judged longer than the visual stimuli. However, this modality distortion in time judgment was higher in the younger children. Statistical analyses revealed that the size of this time distortion was directly related to individual working memory capacities.

Synchrony and emotion in children and adults.

This study examined both the development of synchronisation activities and the way emotion affects these activities in children and adults. Children aged from 3 to 8 years, as well as adults, performed a spontaneous motor tempo (SMT) task and a synchronisation task with a 500-millisecond and 700-millisecond inter-stimulus interval (ISI), followed by a continuation task, in both an emotion-free and an emotional context (High-Arousal, Low-Arousal, and Neutral). The results showed that the SMT was faster and more variable in the younger children. In addition, the younger children found it more difficult to slow down their tapping rate in synchrony with the 700-millisecond ISI, with the result that they quickly returned to their internal tempo in the continuation phase. In contrast, the 8-year-olds' synchronisation performance was close to that of the adults. However, despite developmental changes in synchronisation skills, all the participants produced faster tempi in both the SMT and the synchronisation task for the High-Arousal emotion than for the other emotions. This suggests that emotions induce an automatic distortion of motor timing as has also been observed for the perception of time.

High levels of time contraction in young children in dual tasks are related to their limited attention capacities.

Numerous studies have shown that durations are judged shorter in a dual-task condition than in a simple-task condition. The resource-based theory of time perception suggests that this is due to the processing of temporal information, which is a demanding cognitive task that consumes limited attention resources. Our study investigated whether this time contraction in a dual-task condition is greater in younger children and, if so, whether this is specifically related to their limited attention capacities. Children aged 5-7years were given a temporal reproduction task in a simple-task condition and a dual-task condition. In addition, different neuropsychological tests were used to assess not only their attention capacities but also their capacities in terms of working memory and information processing speed. The results showed a shortening of perceived time in the dual task compared with the simple task, and this increased as age decreased. The extent of this shortening effect was directly linked to younger children's limited attentional capacities; the lower their attentional capacities, the greater the time contraction. This study demonstrated that children's errors in time judgments are linked to their cognitive capacities rather than to capacities that are specific to time.

Distinct developmental trajectories for explicit and implicit timing.

Adults and children aged 5 and 8years were given explicit and implicit timing tasks. These tasks were based on the same temporal representation (the temporal interval between two signals), but in the explicit task participants received overt instructions to judge the duration of the interval, whereas in the implicit task they did not receive any temporal instructions and were asked only to press as quickly as possible after the second signal. In addition, participants' cognitive capacities were assessed with different neuropsychological tests. The results showed that temporal variability (i.e., the spread of performance around the reference interval) decreased as a function of age in the explicit task, being higher in the 5-year-olds than in the 8-year-olds and adults. The higher variability in the youngest children was directly linked to their limited cognitive capacity. By contrast, temporal variability in the implicit timing task remained constant across the different age groups and was unrelated to cognitive capacity. Processing of time, therefore, was independent of age in the implicit task but changed with age in the explicit task, thereby demonstrating distinct developmental trajectories for explicit and implicit timing.

The emotional body and time perception.

We examined the effects of emotional bodily expressions on the perception of time. Participants were shown bodily expressions of fear, happiness and sadness in a temporal bisection task featuring different stimulus duration ranges. Stimulus durations were judged to be longer for bodily expressions of fear than for those of sadness, whereas no significant difference was observed between sad and happy postures. In addition, the magnitude of the lengthening effect of fearful versus sad postures increased with duration range. These results suggest that the perception of fearful bodily expressions increases the level of arousal which, in turn, speeds up the internal clock system underlying the representation of time. The effect of bodily expressions on time perception is thus consistent with findings for other highly arousing emotional stimuli, such as emotional facial expressions.

SMA Selectively Codes the Active Accumulation of Temporal, Not Spatial, Magnitude.

Estimating duration depends on the sequential integration (accumulation) of temporal information in working memory. Using fMRI, we directly compared the accumulation of information in temporal versus spatial domains. Participants estimated either the duration or distance of the dynamic trajectory of a moving dot or, in a control condition, a static line stimulus. Comparing the duration versus distance of static lines activated an extensive cortico-striatal network. By contrast, comparing the duration versus distance of dynamic trajectories, both of which required sequential integration of information, activated SMA alone. Indeed, activity in SMA, as well as right inferior occipital cortex, increased parametrically as a function of stimulus duration and also correlated with individual differences in the propensity to overestimate stimulus duration. By contrast, activity in primary visual cortex increased parametrically as a function of stimulus distance. Crucially, a direct comparison of the parametric responses to duration versus distance revealed that activity in SMA increased incrementally as a function of stimulus duration but not as a function of stimulus distance. Collectively, our results indicate that SMA responds to the active accumulation of information selectively in the temporal domain.

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.

Towards a neurodevelopmental cognitive perspective of temporal processing.

The ability to organize and memorize the unfolding of events over time is a fundamental feature of cognition, which develops concurrently with the maturation of the brain. Nonetheless, how temporal processing evolves across the lifetime as well as the links with the underlying neural substrates remains unclear. Here, we intend to retrace the main developmental stages of brain structure, function, and cognition linked to the emergence of timing abilities. This neurodevelopmental perspective aims to untangle the puzzling trajectory of temporal processing aspects across the lifetime, paving the way to novel neuropsychological assessments and cognitive rehabilitation strategies.

Development and relationship between the judgment of the speed of passage of time and the judgment of duration in children.

This study examined the relationships between the awareness of the speed of the passage of time, the judgment of durations and experiential factors in children aged 4-9 years. They were asked to judge the duration and the speed of the passage of time for different intervals (second and minutes), and to rate their feelings (arousal, happiness, sadness, and task difficulty) during each interval. The results indicated that 8-9-year-olds' judgment of the passage of time is extremely flexible and context-dependent, representing the duration and/or the individual changes in subjective experience (emotion). In contrast, young children's judgment of the passage of time was not related to duration. However, their judgments were not given randomly. They judged that time passed more quickly when they felt happier and more alert. The passage-of-time judgment was therefore initially grounded in emotional and sensory-motor experience, i.e., in their perception of changes (acceleration and deceleration) in self-movement (successions of states and their extension). Therefore, duration judgment and passage-of-time judgment initially develop separately and are later combined when children understand the logical link between speed and duration.

Cognitive and plastic recurrent neural network clock model for the judgment of time and its variations.

The aim of this study in the field of computational neurosciences was to simulate and predict inter-individual variability in time judgements with different neuropsychological properties. We propose and test a Simple Recurrent Neural Network-based clock model that is able to account for inter-individual variability in time judgment by adding four new components into the clock system: the first relates to the plasticity of the neural system, the second to the attention allocated to time, the third to the memory of duration, and the fourth to the learning of duration by iteration. A simulation with this model explored its fit with participants' time estimates in a temporal reproduction task undertaken by both children and adults, whose varied cognitive abilities were assessed with neuropsychological tests. The simulation successfully predicted 90% of temporal errors. Our Cognitive and Plastic RNN-Clock model (CP-RNN-Clock), that takes into account the interference arising from a clock system grounded in cognition, was thus validated.

Sex- and age-related differences in the rating of perceived exertion after high-intensity rowing exercise during childhood and adolescence.

The present study aimed to evaluate the effects of age and sex on the rating of perceived exertion (RPE) during high-intensity exercise and determine whether mechanical and physiological parameters could be predictors of RPE during childhood and adolescence. Forty-three boys and 36 girls performed a 60-s all-out test on a rowing ergometer and were categorized by age group (10.0-11.9; 12.0-13.9; 14.0-15.9; 16.0-17.9 years) and sex. Ratings of perceived exertion were assessed using the 6-20 RPE and CR-10 scales and analyzed with respect to mechanical work rate (Wtot ), post-exercise peak blood lactate concentration ([La]peak ), and peak minute ventilation (V̇Epeak ). Multilevel regression modeling revealed a significant influence of Wtot , [La]peak and V̇Epeak on 6-20 RPE and CR-10 scores (r2  = .34 and .36, p < .001, respectively). However, while boys perceived high-intensity exercise as being subjectively more difficult than girls at all ages (p < .05) except 12.0-13.9 years, significant higher mechanical work rate and greater associated metabolic responses in boys than girls were only found from the age of 14 years (Wtot and V̇Epeak ) or 16 years ([La]peak ), suggesting that the association between RPE and mechanical/physiological parameters could not be held before the age of 12 years. To conclude, RPE increased with increasing age, with boys exhibiting higher scores than girls at all ages except 12.0-13.9 years. This finding is probably explained by the higher Wtot and greater concomitant metabolic responses in boys at the time of puberty. However, other factors should be considered at least in children before the age of 12 years.

Experience and memory of time and emotions two years after the start of the COVID-19 pandemic.

In this French longitudinal study, we assessed judgment of the passage of time in current life and the predictors of this judgment 2 years after the onset of the COVID-19 pandemic, i.e., at a time when there was no lockdown and no protective measures. We then compared these measures with the same participants' passage-of-time judgments assessed during each of the past three French lockdowns. We also assessed their memory representations of the passage of time in the past, i.e., for the various lockdowns. The results showed the persistence of the feeling of time slowing down outside of lockdown. However, this was no longer linked to external factors (lack of activity, disruption of everyday routines) as found in the previous studies conducted during the lockdowns, but to an individual internal factor, namely a high level of depression in the general population. Moreover, the results revealed that the experience of the passage of time for the past lockdowns was compressed in memory, being judged to be faster than it actually was. This time compression tended to be greater in depressed people. It was also associated with a positive bias for all the other examined factors (e.g., sleep quality, life routine, boredom, happiness). We assumed that this time compression would be related to processes involved in the recall of unfolding events, with certain moments being omitted or forgotten during recall, as well as to the process of reconstruction in autobiographical memory. Our study therefore shows the long-lasting effect of lockdowns on mental health of the general population, which was expressed by the persistent feeling of a slowing down of time. It is therefore necessary to take care of this psychologically fragile population and to avoid further lockdowns in response to a new health crisis, that they cannot cope with.

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.

Awareness of time distortions and its relation with time judgment: a metacognitive approach.

The perception of time cannot be reduced to a simple percept produced by an internal clock. The aim of the present study was therefore to investigate the role of the individual consciousness of time on temporal judgments. In the present study, the participants' awareness of attention-related time distortions was assessed using a metacognitive questionnaire. The participants were also required to verbally judge a series of stimulus durations in a single or a dual task condition. The results revealed that time was underestimated in the dual task compared to the single task. However, the accuracy of time judgments improved in line with the participants' individual awareness of attentional time distortion: The more aware they were of the role of attention in time perception, the lower the time distortions they exhibited. Conscious awareness of time therefore plays a role in the accuracy of the time judgments made by human beings.