Scalar Timing Theory Research Articles

Time estimation during motor activity.

Several studies on time estimation showed that the estimation of temporal intervals is related to the amount of attention devoted to time. This is explained by the scalar timing theory, which assumes that attention alters the number of pulses transferred by our internal clock to an accumulator that keeps track of the elapsed time. In a previous study, it was found that time underestimation during cognitive-demanding tasks was more pronounced while walking than while sitting, whereas no clear motor-induced effects emerged without a concurrent cognitive task. What remains unclear then is the motor interference itself on time estimation. Here we aim to clarify how the estimation of time can be influenced by demanding motor mechanisms and how different motor activities interact with concurrent cognitive tasks during time estimation. To this purpose, we manipulated simultaneously the difficulty of the cognitive task (solving arithmetic operations) and the motor task. We used an automated body movement that should require no motor or mental effort, a more difficult movement that requires some motor control, and a highly demanding movement requiring motor coordination and attention. We compared the effects of these three types of walking on time estimation accuracy and uncertainty, arithmetic performance, and reaction times. Our findings confirm that time estimation is affected by the difficulty of the cognitive task whereas we did not find any evidence that time estimation changes with the complexity of our motor task, nor an interaction between walking and the concurrent cognitive tasks. We can conclude that walking, although highly demanding, does not have the same effects as other mental tasks on time estimation.

Beyond Scalar Timing Theory: Integrating Neural Oscillators with Computational Accessibility in Memory

Abstract One of the major challenges for computational models of timing and time perception is to identify a neurobiological plausible implementation that predicts various behavioral properties, including the scalar property and retrospective timing. The available timing models primarily focus on the scalar property and prospective timing, while virtually ignoring the computational accessibility. Here, we first selectively review timing models based on ramping activity, oscillatory pattern, and time cells, and discuss potential challenges for the existing models. We then propose a multifrequency oscillatory model that offers computational accessibility, which could account for a much broader range of timing features, including both retrospective and prospective timing.

A systematic exploration of temporal bisection models across sub- and supra-second duration ranges

An integral component to the validity of timing models is their ability to accurately fit behavioral data from detection and discrimination tasks such as the temporal bisection procedure. Two of the most prominent timing models are the Sample Known Exactly (SKE), based on scalar timing theory, and the pseudo-logistic model (PLM). Recently, evidence accumulation models based on drift–diffusionprocesses (DDM) have been utilized for modeling temporal bisection data. Currently, there is no standard by which timing behavioral data are fit, resulting in the implementation of both theoretical and atheoretical models, such as generalized logistic functions (L4P). As differences in timing behavior have been shown across sub- and supra-second durations, a comparative evaluation of these 4 different types of models (SKE, PLM, L4P, and DDM) was conducted to assess each model’s ability to capture these differences using timing data from the temporal bisection procedure. Psychometric functions from rats, trained on a bisection task using sub-sec (200 ms vs. 800 ms.) and supra-sec (2 s vs. 8 s) conditions, were fit with each of the four models. Using Akaike Information Criterion (AIC) we demonstrate that theoretical models vastly outperformed the L4P across both duration ranges, Furthermore, significant differences existed in key parameters between L4P and PLM. Three DDM models were analyzed with varying degrees of freedom, which showed that allowing for non-decision time, drift rate, and starting point to vary across signal durations outperform simpler models (Δi≥ 10) that only allowed for variation in drift rate or drift rate and starting point. These models explained variance in both choice and reaction time data. While we were unable to directly compare timing and temporal decision models the results from both demonstrate the need for a shift toward theoretically based models such as the SKE, PLM, or DDM which provide greater parsimony as well as provide for greater qualitative analysis and interpretation of the data.

The right dorsolateral prefrontal cortex is essential in seconds range timing, but not in milliseconds range timing: An investigation with transcranial direct current stimulation

It is unclear whether altering the activity of the right dorsolateral prefrontal cortex (right DLPFC) affects an individual’s timing performance in milliseconds- and seconds range timing. Here we investigated the causal role of right DLPFC in milliseconds- and seconds range timing with a temporal bisection task under the application of transcranial direct current stimulation (tDCS) that altered the neural activities of the right DLPFC. The tDCS conditions consisted of anodal, cathodal, and sham conditions. The electrodes were placed over the F4 position (10–20 system) and on the left supraorbital forehead. In current study, participants completed two blocks of trials involving short (“Short blocks”: 200–800 ms) or longer (“Long blocks”: 1400–2600 ms) durations. The results showed that no significant differences in the bisection point (BP) were found among anodal condition, sham condition and cathodal condition in “Short blocks”. However, in “Long blocks”, the BP were found to be shifted toward the left for the anodal condition, sham condition, compared to cathodal condition, suggesting that the stimulus duration was judged to last longer for anodal condition compared to sham condition, whereas shorter for cathodal condition compared to sham condition. The results demonstrated that the right DLPFC played a causal role in seconds range timing (average duration 2000 ms), but not in milliseconds range timing (average duration 500 ms), which is shown it might be involved in the cognitive processing (for example, working memory process) based on dual-timing system and scalar timing theory.

Interval timing is disrupted in female 5xFAD mice: An indication of altered memory processes.

Temporal information processing in the seconds-to-minutes range is disrupted in patients with Alzheimer's disease (AD). In this study, we investigated the timing behavior of the 5xFAD mouse model of AD in the peak interval (PI) procedure. Nine-month-old female mice were trained with sucrose solution reinforcement for their first response after a fixed-interval (FI) and tested in the inter-mixed non-reinforced PI trials that lasted longer than FI. Timing performance indices were estimated from steady-state timed anticipatory nose-poking responses in the PI trials. We found that the time of maximal reward expectancy (peak time) of the 5xFAD mice was significantly earlier than that of the wild-type (WT) controls with no differences in other indices of timing performance. These behavioral differences corroborate the findings of previous studies on the disruption of temporal associative memory abilities of 5xFAD mice and can be accounted for by the scalar timing theory based on altered long-term memory consolidation of temporal information in the 5xFAD mice. This is the first study to directly show an interval timing phenotype in a genetic mouse model of AD.

Modality differences in timing and the filled-duration illusion: Testing the pacemaker rate explanation

Performance in temporal difference threshold and estimation tasks is markedly less accurate for visual than for auditory intervals. In addition, thresholds and estimates are likewise less accurate for empty than for filled intervals. In scalar timing theory, these differences have been explained as alterations in pacemaker rate, which is faster for auditory and filled intervals than for visual and empty intervals. We tested this explanation according to three research aims. First, we replicated the threshold and estimation tasks of Jones, Poliakoff, and Wells (Quarterly Journal of Experimental Psychology, 62, 2171–2186, 2009) and found the well-documented greater precision for auditory than visual intervals, and for filled than for empty intervals. Second, we considered inter-individual differences in these classic effects and found that up to 27% of participants exhibited opposite patterns. Finally, we examined intra-individual differences to investigate (i) whether thresholds and estimates correlate within each stimulus condition and (ii) whether the stimulus condition in which a participants’ pacemaker rate was highest was the same in both tasks. Here we found that if pacemaker rate is indeed a driving factor for thresholds and estimates, its effect may be greater for empty intervals, where the two tasks correlate, than for filled intervals, where they do not. In addition, it was more common for participants to perform best in different modalities in each task, though this was not true for ordinal intra-individual differences in the filled-duration illusion. Overall, this research presents several findings inconsistent with the pacemaker rate explanation.

面部表情对时距知觉的影响研究综述

面部表情通过所表达的情绪会影响个体的唤醒，也会对个体的注意产生影响。唤醒和注意是影响时距知觉的主要因素，因此面部表情会影响时距知觉。已有大量研究探讨了面部表情对时距知觉的影响，发现不同面部表情对时距知觉的影响有所不同。文章首先梳理了高兴、愤怒、恐惧、悲伤和厌恶面部表情影响时距知觉的实证研究；然后，以标量计时理论对面部表情影响时距知觉的原因进行归纳和解释；最后，提出该领域未来的研究方向：探讨眼睛在面部表情影响时距知觉中的作用，以及面部表情对秒上、秒下时距知觉的影响。 The emotion which is expressed by facial expression not only affects individual’s arousal, but also affects individual’s attention. As arousal and attention are the main factors that affect duration perception, facial expressions can affect duration perception. A lot of studies have investigated the influence of facial expression on duration perception, and found that the influence on duration perception is different across facial expression. Present article reviewed empirical researches about the influence of facial expression on duration perception including joy, anger, fear, sadness and disgust. The scalar timing theory could be used to explain the reasons of how facial expression affects duration perception. Future studies should aim at the following two aspects: the effect of eye on facial expression affecting duration perception, and the influence of facial expression on sub-second and supra-second duration perception.

A Brief History of “The Psychology of Time Perception”

Basic mechanisms of interval timing and associative learning are shared by many animal species, and develop quickly in early life, particularly across infancy, and childhood. Indeed, John Wearden in his book “The Psychology of Time Perception”, which is based on decades of his own research with colleagues, and which our commentary serves to primarily review, has been instrumental in implementing animal models and methods in children and adults, and has revealed important similarities (and differences) between human timing (and that of animals) when considered within the context of scalar timing theory. These seminal studies provide a firm foundation upon which the contemporary multifaceted field of timing and time perception has since advanced. The contents of the book are arguably one piece of a larger puzzle, and as Wearden cautions, “The reader is warned that my own contribution to the field has been exaggerated here, but if you are not interested in your own work, why would anyone else be?” Surely there will be many interested readers, however the book is noticeably lacking in it neurobiological perspective. The mind (however it is conceived) needs a brain (even if behaviorists tend to say “the brain behaves”, and most neuroscientists currently have a tenuous grasp on the neural mechanisms of temporal cognition), and to truly understand the psychology of time, brain and behavior must go hand in hand regardless of the twists, turns, and detours along the way.

Effects of dorsal hippocampal damage on conditioning and conditioned-response timing: A pooled analysis.

Behavioral findings suggest that the dorsal hippocampus (DHPC) plays a role in timing of appetitive conditioned responding. The present article explored the relationship between the extent of DHPC damage and timing ability, in a pooled analysis of three published studies from our laboratory. Initial analyses of variance confirmed our previous reports that DHPC damage reduced peak time (a measure of timing accuracy). However, the spread (a measure of timing precision) was unchanged, such that the coefficient of variation (spread/peak time) was significantly larger in DHPC-lesioned animals. This implies that, in addition to the well-established effect of DHPC lesions on timing accuracy, DHPC damage produced a deficit in precision of timing. To complement this analysis, different generalized linear mixed-effects models (GLMMs) were performed on the combined dataset, to examine which combinations of the different behavioral measures of timing were the best predictors of the degree of hippocampal damage. The results from the GLMM analysis suggested that the greater the DHPC damage, the greater the absolute difference between the observed peak time and reinforced duration. Nevertheless, this systematic relationship between damage and performance was not specific to the temporal domain: paradoxically the greater the damage the greater the magnitude of peak responding. We discuss these lesion effects in terms of scalar timing theory.

How Symbolic Meaning Influences Time Perception in Primary School Children and Adults

The time dimension is always embedded in any human experience and is an inseparable part of it. According to scalar timing theory, timing behavior is based on the output of an internal clock that provides long-term memory representations that can be retrieved and compared with the representation of the current temporal interval held in short-term memory. More precisely, the model includes a pacemaker, a switch, and an accumulator. At the onset of a timed stimulus, the switch closes, thereby allowing pulses emitted by the pacemaker to enter the accumulator. At the offset of the stimulus, the switch opens and pulse transfer terminates. Thus, representation of stimulus duration depends on the number of pulses accumulated during the stimulus presentation. According to the model, a temporal judgment results from a comparison, via the decision mechanism, of this representation of stimulus duration with longer-term representations of biologically significant durations experienced previously. However, the relevance and importance of time is not constant but varies depending on the meaning assigned to a certain situation. The present study investigated how symbolic meaning affectes time perception in school children and adults. In particular, we investigated how children experience time and how the environment acts on children subjective experience of time. Stimuli with different symbolic meaning are be employed (the meaning of fastness or slowness). In the present study we employed two stimuli, one that recalls the meaning of fastness (motorbike) and one that recalls the meaning of slowness (bicycle). We predicted that observing a stimulus that recall the meaning of speed affect participant's performance in the way that stimuli that recall the meaning of fastness will be under-reproduced and stimuli that recall the meaning of slowness will be over- reproduced. Two experiments are presented. Experiment 1 included two hundred participants divided in 9 different groups according to their school class: 5 groups belonged to primary school, 3 groups were middle school, and 1 group was of university students. Participants were engaged in a time reproduction task in which a motorbike or a bicycle were presented for 11, 21, and 36 s. After the presentation of the standard duration, participants were required to press the space bar to reproduce the duration previously presented. Significant differences between groups were found. Younger participants under-reproduced the duration more than did older participants. Importantly, an effect of symbolic meaning was found in youngre participants (up to 8 years old) older participants did not present any effect of symbolic meaning. We reasoned that the time reproduction task might not be the appropriate method to investigate time perception in older participants in particular when longer durations are employed. Experiment 2 included twenty university students. The visual stimuli were four pictures representing a bicycle and a motorbike and a bicycle and a motorbike driven by a person. Participants were engaged in a time bisection task: standard short 400ms and the standard long was 1600ms. Each standard duration was presented 10 times. After the training phase participants were required to perform 4 blocks. In each block, the four pictures were presented 7 times for each of the comparison durations (400, 600, 800, 1000, 1200, 1400, 1600ms; total 196 trials in each block). The participants were asked to respond with their left and right index finger and response keys were counterbalanced between participants. The cumulative normal function was fitted to the resulting curves. We calculated the temporal bisection point as index of perceived duration; the observed shift of the bisection point for the different vehicles presented can be interrelated as an indicator of differences in perceiving duration. Thus, longer perceived durations are reflected by smaller bisection points values. Results confirmed and extended previous findings observed with younger participants. When the stimulus presented recalled the meaning of fastness, temporal intervals were under- estimated, whereas, when the stimulus presented recalled the meaning of slowness, temporal intervals were over-estimated. The present study also pointed out the importance of selecting the appropriate method to investigate time perception.

Dedicated clock/timing-circuit theories of time perception and timed performance.

Scalar Timing Theory (an information-processing version of Scalar Expectancy Theory) and its evolution into the neurobiologically plausible Striatal Beat-Frequency (SBF) theory of interval timing are reviewed. These pacemaker/accumulator or oscillation/coincidence detection models are then integrated with the Adaptive Control of Thought-Rational (ACT-R) cognitive architecture as dedicated timing modules that are able to make use of the memory and decision-making mechanisms contained in ACT-R. The different predictions made by the incorporation of these timing modules into ACT-R are discussed as well as the potential limitations. Novel implementations of the original SBF model that allow it to be incorporated into ACT-R in a more fundamental fashion than the earlier simulations of Scalar Timing Theory are also considered in conjunction with the proposed properties and neural correlates of the "internal clock".

Estimating averages from distributions of tone durations

We examined whether estimating average duration was influenced by the distribution peak location. We presented participants with samples of various tone durations and then presented comparison tone durations. Participants judged whether each comparison duration was longer than the average sample duration. Estimates of the averages were inferred from the psychophysical functions. The durations were sampled from three distributions: one positively skewed, one symmetric, and one negatively skewed. In Experiment 1, every participant was presented with every distribution. Estimates of the averages were unbiased for the symmetric distribution but were biased toward the long tail of each skewed distribution. This would occur if participants combined the sample to be judged with the previous, irrelevant samples, or with the comparison durations. In Experiment 2, each participant was presented with samples from only one of the distributions. Estimates of the averages were still biased toward the long tails of the skewed distributions. This would occur if participants combined the sample to be judged with the comparison durations, which were the same for the three distributions. In Experiment 3, each participant was presented with only one distribution, and each distribution was tested with its own comparison durations, selected as percentiles from the distribution. The estimates were accurate for the smallest population mean (positively skewed distribution) but underestimated the larger means. These results could be explained by subjective shortening of the durations in memory, with a simple equation from scalar timing theory. This equation correctly predicted two results: The estimated averages were a linear function of the stimulus means, and the variances were a linear function of the squared stimulus means. Neither prediction was dependent on the skewness of the stimulus durations.

Hippocampus, time, and memory--a retrospective analysis.

In 1984, there was considerable evidence that the hippocampus was important for spatial learning and some evidence that it was also involved in duration discrimination. The article "Hippocampus, Time, and Memory" (Meck, Church, & Olton, 1984), however, was the first to isolate the effects of hippocampal damage on specific stages of temporal processing. In this review, to celebrate the 30th anniversary of Behavioral Neuroscience, we look back on factors that contributed to the long-lasting influence of this article. The major results were that a fimbria-fornix lesion (a) interferes with the ability to retain information in temporal working memory, and (b) distorts the content of temporal reference memory, but (c) did not decrease sensitivity to signal duration. This was the first lesion experiment in which the results were interpreted by a well-developed theory of behavior (scalar timing theory). It has led to extensive research on the role of the hippocampus in temporal processing by many investigators. The most important ones are the development of computational models with plausible neural mechanisms (such as the striatal beat-frequency model of interval timing), the use of multiple behavioral measures of timing, and empirical research on the neural mechanisms of timing and temporal memory using ensemble recording of neurons in prefrontal-striatal-hippocampal circuits.

Pathophysiological distortions in time perception and timed performance

Distortions in time perception and timed performance are presented by a number of different neurological and psychiatric conditions (e.g. Parkinson's disease, schizophrenia, attention deficit hyperactivity disorder and autism). As a consequence, the primary focus of this review is on factors that define or produce systematic changes in the attention, clock, memory and decision stages of temporal processing as originally defined by Scalar Expectancy Theory. These findings are used to evaluate the Striatal Beat Frequency Theory, which is a neurobiological model of interval timing based upon the coincidence detection of oscillatory processes in corticostriatal circuits that can be mapped onto the stages of information processing proposed by Scalar Timing Theory.

Modality differences in timing and temporal memory throughout the lifespan

The perception of time is heavily influenced by attention and memory, both of which change over the lifespan. In the current study, children (8 yrs), young adults (18–25 yrs), and older adults (60–75 yrs) were tested on a duration bisection procedure using 3 and 6-s auditory and visual signals as anchor durations. During test, participants were exposed to a range of intermediate durations, and the task was to indicate whether test durations were closer to the “short” or “long” anchor. All groups reproduced the classic finding that “sounds are judged longer than lights”. This effect was greater for older adults and children than for young adults, but for different reasons. Replicating previous results, older adults made similar auditory judgments as young adults, but underestimated the duration of visual test stimuli. Children showed the opposite pattern, with similar visual judgments as young adults but overestimation of auditory stimuli. Psychometric functions were analyzed using the Sample Known Exactly-Mixed Memory quantitative model of the Scalar Timing Theory of interval timing. Results indicate that children show an auditory-specific deficit in reference memory for the anchors, rather than a general bias to overestimate time and that aged adults show an exaggerated tendency to judge visual stimuli as “short” due to a reduction in the availability of controlled attention.

Possible Functions of Prefrontal Cortical Neurons in Duration Discrimination

Possible Functions of Prefrontal Cortical Neurons in Duration Discrimination

Differences in duration discrimination of filled and empty auditory intervals as a function of base duration

In the present experiments, participants were presented with two time intervals that were marked by auditory signals, and their task was to decide which of the two was longer in duration. In Experiment 1, the base durations were 50 and 1,000 msec, whereas in Experiment 2, seven different base durations ranging from 50 to 1,000 msec were employed. It was found that filled intervals (continuous tones) were discriminated more accurately than empty intervals (with onset and offset marked by clicks) at the 50-msec base duration, whereas no performance differences could be shown for longer ones. The findings are consistent with the notion of a unitary timing mechanism that governs the timing of both filled and empty auditory intervals, independent of base durations. A likely conceptual framework that could explain better performance with filled as compared with empty intervals represents an information-processing model of interval timing that evolved from scalar timing theory. According to this account, a performance decrement observed with empty intervals may be due to a misassignment of pulses generated by an internal pacemaker.

Anticipatory pursuit is influenced by a concurrent timing task

The ability to predict upcoming events is important to compensate for relatively long sensory-motor delays. When stimuli are temporally regular, their prediction depends on a representation of elapsed time. However, it is well known that the allocation of attention to the timing of an upcoming event alters this representation. The role of attention on the temporal processing component of prediction was investigated in a visual smooth pursuit task that was performed either in isolation or concurrently with a manual response task. Subjects used smooth pursuit eye movements to accurately track a moving target after a constant-duration delay interval. In the manual response task, subjects had to estimate the instant of target motion onset by pressing a button. The onset of anticipatory pursuit eye movements was used to quantify the subject's estimate of elapsed time. We found that onset times were delayed significantly in the presence of the concurrent manual task relative to the pursuit task in isolation. There was also a correlation between the oculomotor and manual response latencies. In the framework of Scalar Timing Theory, the results are consistent with a centralized attentional gating mechanism that allocates clock resources between smooth pursuit preparation and the parallel timing task.

Veränderungen der Zeitbeurteilung im Alter

Time perception can be divided into two processes: time experience and time judgement. Although there have been frequent reports of changes in these two processes with increasing age, none of these changes has been demonstrated using objective measures. We evaluated time judgement by employing time estimation, time production, and time reproduction tasks in 33 healthy subjects of all age groups. In addition, we used the Trail-Making Test to measure attentional performance. For both time estimation and time reproduction, we found positive correlations between length of time interval and age (overestimation). After we calculated partial correlations controlling for the results of the Trail-Making Test, the age-related changes we initially observed in the time estimation task disappeared, but the age-related changes seen in the time reproduction task remained significant. Considering the Scalar Timing Theory and the Attentional Gate Theory, our findings indicated that age-related effects on time estimation may be due to attentional factors. In contrast, the age-related changes seen in the time reproduction task may be due to disturbances in working memory function.

Internal clock processes and the filled-duration illusion.

In 3 experiments, the authors compared duration judgments of filled stimuli (tones) with unfilled ones (intervals defined by clicks or gaps in tones). Temporal generalization procedures (Experiment 1) and verbal estimation procedures (Experiments 2 and 3) all showed that subjective durations of the tones were considerably longer than those of unfilled intervals defined either by clicks or gaps, with the unfilled intervals being judged as approximately 55%-65% of the duration of the filled ones when real duration was the same. Analyses derived from the pacemaker-switch-accumulator clock model incorporated into scalar timing theory suggested that the filled/unfilled difference in mean estimates was due to higher pacemaker speed in the former case, although conclusively ruling out alternative interpretations in terms of attention remains difficult.