Neurocomputational Models of Interval Timing: Seeing the Forest for the Trees.

Extracting temporal regularities and relations from experience/observation is critical for organisms' adaptiveness (communication, foraging, predation, prediction) in their ecological niches. Therefore, it is not surprising that the internal clock that enables the perception of seconds-to-minutes-long intervals (interval timing) is evolutionarily well-preserved across many species of animals. This comparative claim is primarily supported by the fact that the timing behavior of many vertebrates exhibits common statistical signatures (e.g., on-average accuracy, scalar variability, positive skew). These ubiquitous statistical features of timing behaviors serve as empirical benchmarks for modelers in their efforts to unravel the processing dynamics of the internal clock (namely answering how internal clock "ticks"). In this chapter, we introduce prominent (neuro)computational approaches to modeling interval timing at a level that can be understood by general audience. These models include Treisman's pacemaker accumulator model, the information processing variant of scalar expectancy theory, the striatal beat frequency model, behavioral expectancy theory, the learning to time model, the time-adaptive opponent Poisson drift-diffusion model, time cell models, and neural trajectory models. Crucially, we discuss these models within an overarching conceptual framework that categorizes different models as threshold vs. clock-adaptive models and as dedicated clock/ramping vs. emergent time/population code models.

Memory capacity as the core mechanism of the development of space-time interferences in children.

This study investigated the development of spatiotemporal perceptual interactions in 5-to-7 years old children. Participants reproduced the temporal and spatial interval between sequentially presented visual stimuli. The time and spacing between stimuli were experimentally manipulated. In addition, cognitive capacities were assessed using neuropsychological tests. Results revealed that starting at 5 years old, children exhibited spatial biases in their time estimations and temporal biases in their spatial estimations, pointing at space-time interference. In line with developmental improvement of temporal and spatial abilities, these spatiotemporal biases decreased with age. Importantly, short-term memory capacity was a predictor of space-time interference pointing to shared cognitive mechanisms between time and space processing. Our results support the symmetrical hypothesis that proposes a common neurocognitive mechanism for processing time and space.

Bayes Optimal Integration of Social and Endogenous Uncertainty in Numerosity Estimation.

One of the most prominent social influences on human decision making is conformity, which is even more prominent when the perceptual information is ambiguous. The Bayes optimal solution to this problem entails weighting the relative reliability of cognitive information and perceptual signals in constructing the percept from self-sourced/endogenous and social sources, respectively. The current study investigated whether humans integrate the statistics (i.e., mean and variance) of endogenous perceptual and social information in a Bayes optimal way while estimating numerosities. Our results demonstrated adjustment of initial estimations toward group means only when group estimations were more reliable (or "certain"), compared to participants' endogenous metric uncertainty. Our results support Bayes optimal social conformity while also pointing to an implicit form of metacognition.

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.

Metric error monitoring as a component of metacognitive processing.

Metacognitive processing constitutes one of the contemporary target domains in consciousness research. Error monitoring (the ability to correctly report one's own errors without feedback) is considered one of the functional outcomes of metacognitive processing. Error monitoring is traditionally investigated as part of categorical decisions where choice accuracy is a binary construct (choice is either correct or incorrect). However, recent studies revealed that this ability is characterized by metric features (i.e., direction and magnitude) in temporal, spatial, and numerical domains. Here, we discuss methodological approaches to investigating metric error monitoring in both humans and non-human animals and review their findings. The potential neural substrates of metric error monitoring measures are also discussed. This new scope of metacognitive processing can help improve our current understanding of conscious processing from a new perspective. Thus, by summarizing and discussing the perspectives, findings, and common applications in the metric error monitoring literature, this paper aims to provide a guideline for future research.

Temporal Error Monitoring Does Not Depend on Working Memory.

Working memory (WM) and metacognition has been documented to be in a reciprocal relationship. This study aims to address if temporal error monitoring performance can be diminished with increased working memory load. We hypothesized that if temporal error monitoring has commonalities with perceptual error monitoring, temporal error monitoring performance should be diminished by increased working memory load. Participants completed a temporal error monitoring task in a dual task design in which the secondary task was a letter alphabetization task. Results revealed no disrupting effect of WM load on either confidence or short-long judgments as being different metrics of temporal error monitoring ability. These results demonstrate that unlike perceptual error monitoring, WM and temporal error monitoring have distinct processing mechanisms. With this result, the current study suggests that temporal and perceptual error monitoring may partially rely on different mechanisms. Results are discussed within A Theory of Magnitude (ATOM), pacemaker-accumulator model and temporal error monitoring frameworks.

Working memory for time intervals: Another manifestation of the central tendency effect.

The relationship between working memory and time perception has been typically investigated using dual-task paradigms (e.g., testing timing performance during a concurrent task). To our knowledge, none of these studies used time intervals as the target stimulus to be remembered. The current study investigated the working memory for time intervals by asking participants to reproduce durations they experienced at different orders in a series of experienced intervals (n-back task). One of the experiments was conducted online and the other one in the lab setting. Results showed a central tendency bias and additive elongation of time reproductions with increasing working memory load. Our results also showed that participants assigned different weights to experienced intervals based on their order of presentation (higher weight to the target interval). We conclude that the recall of intervals from working memory under high cognitive load leads to a central tendency effect, which is known to be induced by the temporal context and present particularly in aging and in those with Parkinson's disease.

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.

Humans can monitor trial-based but not global timing errors: Evidence for relative judgements in temporal error monitoring.

Humans can monitor the magnitude and direction of their temporal errors in individual trials. Based on the predictions of our model of temporal error monitoring that rely on a relative comparison of internal clock readings, we predict that participants would monitor their timing errors in individual trials, but not the direction of their global timing errors without external feedback. One study has indeed found that accurate self-monitoring of average timing biases required external feedback with directional information. The current study investigates how different sources of feedback (i.e., internal or external) affect performance in the self-monitoring of average timing bias. Four groups of participants were tested in a temporal reproduction task. Participants in the self-evaluation condition evaluated the direction and size of their time reproduction errors in individual trials. In the accurate feedback condition, participants received explicit trial-based feedback regarding the direction of their error while participants in the partially accurate feedback condition received trial-based feedback according to the accuracy of short-long judgements of another participant in the self-evaluation condition. Participants in the control condition reproduced only the target duration without making any judgements regarding their reproduction performance or receiving any external feedback about it. Results showed that while participants accurately monitor timing errors in individual trials, in none of the experimental conditions were they more accurate than the chance level in terms of evaluating the direction of their average temporal bias. We discuss these results in terms of the temporal error monitoring model introduced by Akdogan and Balci. Thus, our findings suggest that external directional feedback does not have any informational value for global temporal bias judgements above and beyond internal self-monitoring.

Mice make temporal inferences about novel locations based on previously learned spatiotemporal contingencies.

Animals learn multiple spatiotemporal contingencies and organize their anticipatory responses accordingly. The representational/computational capacity that underlies such spatiotemporally guided behaviors is not fully understood. To this end, we investigated whether mice make temporal inferences of novel locations based on previously learned spatiotemporal contingencies. We trained 18 C57BL/6J mice to anticipate reward after three different intervals at three different locations and tested their temporal expectations of a reward at five locations simultaneously, including two locations that were not previously associated with reward delivery but adjacent to the previously trained locations. If mice made spatiotemporal inferences, they were expected to interpolate between duration pairs associated with previously reinforced hoppers surrounding the novel hopper. We found that the maximal response rate at the novel locations indeed fell between the two intervals reinforced at the surrounding hoppers. We argue that this pattern of responding might be underlain by spatially constrained Bayesian computations.

Metric error monitoring for a cleaner record of timing.

A recent line of research has shown that humans can keep track of the direction and magnitude of their timing errors without relying on feedback. But these studies tested temporal error monitoring explicitly by interrogating participants regarding their errors, which might have inadvertently primed the prospective coupling between the first-order timing and second-order metacognitive judgments. The current study utilized an indirect way of testing temporal error awareness while providing a strong objective incentive for maximizing the accuracy of first-order timing performance. In two experiments, participants were asked to maximize the average proximity of their time reproduction to the target by accepting or rejecting their time reproduction depending on the subjective judgment of their proximity to the target time interval. We found that participants more frequently opted out of a trial with a larger distance between their reproductions and the target time interval in both directions, forming a positive quadratic relationship with reproduced time. Resultantly, timing precision was lower in trials that participants opted out of. Our results provide new evidence in support of the temporal error-monitoring performance of human participants. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The Blursday database as a resource to study subjective temporalities during COVID-19.

The COVID-19 pandemic and associated lockdowns triggered worldwide changes in the daily routines of human experience. The Blursday database provides repeated measures of subjective time and related processes from participants in nine countries tested on 14 questionnaires and 15 behavioural tasks during the COVID-19 pandemic. A total of 2,840 participants completed at least one task, and 439 participants completed all tasks in the first session. The database and all data collection tools are accessible to researchers for studying the effects of social isolation on temporal information processing, time perspective, decision-making, sleep, metacognition, attention, memory, self-perception and mindfulness. Blursday includes quantitative statistics such as sleep patterns, personality traits, psychological well-being and lockdown indices. The database provides quantitative insights on the effects of lockdown (stringency and mobility) and subjective confinement on time perception (duration, passage of time and temporal distances). Perceived isolation affects time perception, and we report an inter-individual central tendency effect in retrospective duration estimation.

Count-based decision-making in mice: numerosity vs. stimulus control.

Numerical and temporal control of behavior is ubiquitous across many species of animals. Recent studies showed that in the presence of reliable discriminative stimuli, mice ignore temporal relations and probabilistic information but when discriminative stimuli become non-informative, the same mice can spontaneously start relying on previously experienced time intervals and probabilities. Similar dynamics do not readily generalize to counting behavior since the response-outcome contingency functions differ when reinforcement depends on the number vs. timing of responding. In the current study, mice (N = 32) learned to press two different levers 10 (few) or 20 (many) times, while the active lever was signaled by a light stimulus. The probability of the few/many trials was manipulated between groups. During testing, the informative value of light stimulus was eliminated by signaling both few- and many-levers. In a quarter of training trials, mice ignored the discriminative stimulus and adopted a numerical decision strategy (starting to respond on the few-option and then switching to the many-option in many trials) that was sensitive to probabilistic information. The frequency but not the probability-sensitive parametrization of switching behavior changed when the discriminative stimulus became non-informative in testing. These findings suggest that there is a relatively strong representational control over counting behavior even in conditions that afford strong stimulus control.

Elucidating the Common Basis for Task-Dependent Differential Manifestations of Category Advantage: A Decision Theoretic Approach.

Cross-category hues are differentiated easier than otherwise equidistant hues that belong to the same linguistic category. This effect is typically manifested through both accuracy and response time gains in tasks with a memory component, whereas only response times are affected when there is no memory component. This raises the question of whether there is a common generative process underlying the differential behavioral manifestations of category advantage in color perception. For instance, within the framework of noisy evidence accumulation models, changes in accuracy can be readily attributed to an increase in the efficacy of perceptual evidence integration (after controlling for threshold setting), whereas changes in response time can also be attributed to shorter nondecisional delays (e.g., due to facilitated signal detection). To address the latent decision processes underlying category advantage across different behavioral demands, we introduce a decision-theoretic perspective (i.e., diffusion decision model) to categorical color perception in three complementary experiments. In Experiment 1, we collected data from a binary color naming task (1) to determine the green-blue boundary in our sample and (2) to trace how parameter estimates of interest in the model output change as a function of color typicality. In Experiments 2 and 3, we used same-different task paradigms (with and without a memory component, respectively) and traced the category advantage in color discrimination in two parameters of the diffusion decision model: nondecision time and drift rate. An increase in drift rate predominantly characterized the category advantage in both tasks. Our results show that improved efficiency in perceptual evidence integration is a common driving force behind different manifestations of category advantage.

The ventral hippocampus CA3 is critical in regulating timing uncertainty in temporal decision-making.

Timing uncertainty is a critical component of temporal decision-making, as it determines the decision strategies that maximize reward rate. However, little is known about the biological substrates of timing uncertainty. In this study, we report that the CA3 subregion of the ventral hippocampus (vCA3), a relatively unexplored area in timing, is critical in regulating timing uncertainty that informs temporal decision making. Using a variant of the differential reinforcement of low rates of responding (DRL) task that incorporates differential levels of approach-avoidance conflict, rats were trained to wait a minimum of 6 s to earn a reward that was paired with varying durations of foot shock. Post-training chemogenetic inhibition of the vCA3 reduced timing uncertainty without affecting mean wait times, irrespective of the level of conflict experienced. Simulations based on the information-processing variant of scalar expectancy theory (SET) revealed that the vCA3 may be important in modulating decision threshold or switch closure latency variability.

Metric error monitoring: Another generalized mechanism for magnitude representations?

Error monitoring refers to the ability to monitor one's own task performance without explicit feedback. This ability is studied typically in two-alternative forced-choice (2AFC) paradigms. Recent research showed that humans can also keep track of the magnitude and direction of errors in different magnitude domains (e.g., numerosity, duration, length). Based on the evidence that suggests a shared mechanism for magnitude representations, we aimed to investigate whether metric error monitoring ability is commonly governed across different magnitude domains. Participants reproduced/estimated temporal, numerical, and spatial magnitudes after which they rated their confidence regarding first order task performance and judged the direction of their reproduction/estimation errors. Participants were also tested in a 2AFC perceptual decision task and provided confidence ratings regarding their decisions. Results showed that variability in reproductions/estimations and metric error monitoring ability, as measured by combining confidence and error direction judgements, were positively related across temporal, spatial, and numerical domains. Metacognitive sensitivity in these metric domains was also positively associated with each other but not with metacognitive sensitivity in the 2AFC perceptual decision task. In conclusion, the current findings point at a general metric error monitoring ability that is shared across different metric domains with limited generalizability to perceptual decision-making.

Etanercept rescues cognitive deficits, depression-like symptoms, and spike-wave discharge incidence in WAG/Rij rat model of absence epilepsy.

Pro-inflammatory cytokines have been shown to be associated with the development of seizures in the WAG/Rij rat model of absence epilepsy. Importantly, WAG/Rij rats also exhibit cognitive deficits and depression-like behaviors. It is possible that pro-inflammatory cytokines mediate these comorbid conditions of absence epilepsy given their well-established effects on cognition and affective responses. The current study investigated the potential therapeutic effect of etanercept (tumor necrosis factor inhibitor) on cognitive impairment, depression-like behavior, and spike-wave discharges (SWDs) typically observed in the WAG/Rij rats. Eight-month-old male WAG/Rij rats and Wistar controls were tested in Morris water maze (MWM), passive avoidance (PA), forced swimming, sucrose preference, and locomotor activity tests, and electroencephalogram (EEG) recordings were taken from a separate group of WAG/Rij rats after 8 weeks of etanercept or vehicle treatment. Consistent with earlier work, WAG/Rij rats exhibited cognitive deficits and depression-like behavior. From these, the cognitive deficits and despair-like behavior were rescued by etanercept administration, which also reduced the frequency of SWDs without affecting their duration. Our results support the hypothesis that pro-inflammatory cytokines mediate the absence seizures and comorbid symptoms of absence epilepsy.