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Chronostasis
Chronostasis
Chronostasis
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Chronostasis (from Greek χρόνος, chrónos, 'time' and στάσις, stásis, 'standing') is a type of temporal illusion in which the first impression following the introduction of a new event or task-demand to the brain can appear to be extended in time.[1] For example, chronostasis temporarily occurs when fixating on a target stimulus, immediately following a saccade (i.e., quick eye movement). This elicits an overestimation in the temporal duration for which that target stimulus (i.e., postsaccadic stimulus) was perceived. This effect can extend apparent durations by up to half a second and is consistent with the idea that the visual system models events prior to perception.[2]

A common occurrence of this illusion is known as the stopped-clock illusion, where the second hand of an analog clock appears to stay still for longer than normal when first looked at.[3][4][5][6]

This illusion can also occur in the auditory and tactile domain. For instance, a study suggests that a caller who listens to a ringing tone through a telephone while repetitively switching the receiver from one ear to the other may overestimate the temporal duration between rings.[1]

Mechanism of action

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Overall, chronostasis occurs as a result of a disconnection in the communication between visual sensation and perception. Sensation, information collected from our eyes, is usually directly interpreted to create our perception. This perception is the collection of information that we consciously interpret from visual information.[7] However, quick eye movements known as saccades disrupt this flow of information. Because research into the neurology associated with visual processing is ongoing, there is renewed debate regarding the exact timing of changes in perception that lead to chronostasis.[8] However, below is a description of the general series of events that lead to chronostasis, using the example of a student looking up from their desk toward a clock in the classroom.

A timeline of the sensation and perception of chronostasis within the context of a student in a classroom
  1. The eyes receive information from the environment regarding one particular focus. This sensory input is sent directly to the visual cortex to be processed. After visual processing, we consciously perceive this object of focus.[9] In the context of a student in a classroom, the student's eyes focus on a paper on their desk. After their eyes collect light reflected off the paper and this information is processed in their visual cortex, the student consciously perceives the paper in front of them.
  2. Following either a conscious decision or an involuntary perception of a stimulus in the periphery of the visual field, the eyes intend to move to a second target of interest.[10] For the student described above, this may occur as they decide that they wish to check the clock at the front of the classroom.
  3. The muscles of the eye contract and it begins to quickly move towards the second object of interest through an action known as a saccade.[11] As soon as this saccade begins, a signal is sent from the eye back to the brain. This signal, known as an efferent cortical trigger or efference copy, communicates to the brain that a saccade is about to begin.[5][12] During saccades, the sensitivity of visual information collected by the eyes is greatly reduced and, thus, any image collected during this saccade is very blurry.[8] In order to prevent the visual cortex from processing blurred sensory information, visual information collected by the eyes during a saccade is suppressed through a process known as saccadic masking. This is also the same mechanism used to prevent the experience of motion blur.[13]
  4. Following the completion of the saccade, the eyes now focus on the second object of interest. As soon as the saccade concludes, another efferent cortical trigger is sent from the eyes back to the brain. This signal communicates to the brain that the saccade has concluded. Prompted by this signal, the visual cortex once again resumes processing visual information.[5] For the student, their eyes have now reached the clock and their brain's visual cortex begins to process information from their eyes. However, this second efferent trigger also communicates to the brain that a period of time has been missing from perception. To fill this gap in perception, visual information is processed in a manner known as neural antedating or backdating.[13] In this visual processing, the gap in perception is "filled in" with information gathered after the saccade. For the student, the gap of time that occurred during the saccade is substituted with the processed image of the clock. Thus, immediately following the saccade, the second hand of the clock appears to stop in place before moving.[14]

In studying chronostasis and its underlying causes, there is potential bias in the experimental setting. In many experiments, participants are asked to perform some sort of task corresponding to sensory stimuli. This could cause the participants to anticipate stimuli, thus leading to bias. Also, many mechanisms involved in chronostasis are complex and difficult to measure. It is difficult for experimenters to observe the perceptive experiences of participants without "being inside their mind."[1] Furthermore, experimenters normally do not have access to the neural circuitry and neurotransmitters located inside the braincases of their subjects.

Modulating factors

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Because of its complexity, there are various characteristics of stimuli and physiological actions that can alter the way one experiences chronostasis.

Saccadic amplitude

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The greater the amplitude (or duration) of a saccade, the more severe the resulting overestimation. The further the student in the above example's eyes must travel in order to reach the clock, the more dramatic their perception of chronostasis.[13] This connection supports the assertion that overestimation occurs in order to fill in the length of time omitted by saccadic masking. This would mean that, if the saccade lasted for a longer period of time, there would be more time that needed to be filled in with overestimation.[15]

Attention redirection

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When shifting focus from one object to a second object, the saccadic movement of one's eyes is also accompanied by a conscious shift of attention. In the context of the stopped clock illusion, not only do your eyes move, but you also shift your attention to the clock. This led researchers to question whether the movement of the eyes or simply the shift of the observer's attention towards the second stimulus initiated saccadic masking. Experiments in which subjects diverted only their attention without moving their eyes revealed that the redirection of attention alone was not enough to initiate chronostasis.[13] This suggests that attention is not the time marker used when perception is filled back in. Rather, the physical movement of the eyes themselves serves as this critical marker. However, this relationship between attention and perception in the context of chronostasis is often difficult to measure and may be biased in a laboratory setting. Because subjects may be biased as they are instructed to perform actions or to redirect their attention, the concept of attention serving as a critical time marker for chronostasis may not be entirely dismissed.[15]

Spatial continuity

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Following investigation, one may wonder if chronostasis still occurs if the saccadic target is moving. In other words, would you still experience chronostasis if the clock you looked at were moving? Through experimentation, researchers found that the occurrence of chronostasis in the presence of a moving stimulus was dependent on the awareness of the subject. If the subject were aware that the saccadic target was moving, they would not experience chronostasis. Conversely, if the subject were not aware of the saccadic target's movement, they did experience chronostasis. This is likely because antedating does not occur in the case of a consciously moving target. If, after the saccade, the eye correctly falls on the target, the brain assumes this target has been at this location throughout the saccade. If the target changes position during the saccade, the interruption of spatial continuity makes the target appear novel.[13]

Stimulus properties

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Properties of stimuli themselves have shown to have significant effects on the occurrence of chronostasis. In particular, the frequency and pattern of stimuli affect the observer's perception of chronostasis. In regard to frequency, the occurrence of many, similar events can exaggerate duration overestimation and makes the effects of chronostasis more severe. In regard to repetition, repetitive stimuli appear to be of shorter subjective duration than novel stimuli.[14] This is due to neural suppression within the cortex. Investigation using various imaging techniques has shown that repetitive firing of the same cortical neurons cause them to be suppressed over time.[16] This occurs as a form of neural adaptation.

Sensory domain

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The occurrence of chronostasis extends beyond the visual domain into the auditory and tactile domains.[17] In the auditory domain, chronostasis and duration overestimation occur when observing auditory stimuli. One common example is a frequent occurrence when making telephone calls. If, while listening to the phone's ring tone, research subjects move the phone from one ear to the other, the length of time between rings appears longer.[1] In the tactile domain, chronostasis has persisted in research subjects as they reach for and grasp objects. After grasping a new object, subjects overestimate the time in which their hand has been in contact with this object.[4] In other experiments, subjects turning a light on with a button were conditioned to experience the light before the button press. This suggests that, much in the same way subjects overestimate the duration of the second hand as they watch it, they may also overestimate the duration of auditory and tactile stimuli. This has led researchers to investigate the possibility that a common timing mechanism or temporal duration scheme is used for temporal perception of stimuli across a variety of sensory domains.[14]

See also

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia

Chronostasis

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from Grokipedia
Chronostasis, commonly known as the stopped clock illusion, is a temporal perceptual illusion in which the first visual stimulus encountered after a rapid , or , subjectively appears to last longer than its actual duration, typically by around 100-200 milliseconds. This effect creates the impression that time briefly "freezes" or dilates at the onset of the new fixation, as experienced when glancing at a and perceiving the second hand to pause. The illusion was first systematically studied in the late 1990s, building on anecdotal reports of distorted during eye shifts, with foundational experiments by Yarrow and colleagues in 2001 demonstrating that the perceived lengthening increases linearly with duration—for instance, a 55° extends perceived time more than a 22° one, by up to 69 milliseconds. Subsequent research confirmed the effect's consistency across various types, including voluntary pro-saccades, anti-saccades, and even involuntary express s, with overestimations ranging from 90 to 192 milliseconds regardless of reaction time differences up to 61 milliseconds. The prevailing explanation, termed the antedating hypothesis, posits that the attributes the post-saccadic stimulus onset to a moment approximately 50 milliseconds before the begins, effectively backdating the event to maintain perceptual continuity during the period of and suppressed awareness inherent to eye movements. This mechanism likely involves a subcortical signal from structures like the , which remaps visual timing without reliance on higher-level voluntary intent, as the illusion persists even in passive or reflexive eye movements. Chronostasis extends beyond vision to other modalities, such as tactile sensations during manual actions, where perceived onset precedes physical contact, suggesting a broader role in integrating sensory events with motor commands. Key experiments have ruled out alternative accounts, like altered internal clock rates, by showing fixed effect sizes across stimulus durations from 100 to 1,333 milliseconds and no dependence on spatial shifts alone. More recent studies indicate modulations by concurrent auditory cues, which can linearly reduce the illusion's magnitude when synchronized with the visual stimulus. Overall, chronostasis highlights the brain's active compensation for oculomotor disruptions, ensuring a stable subjective timeline despite frequent eye movements occurring 3-4 times per second in everyday viewing.

Definition and Overview

Core Phenomenon

Chronostasis is a perceptual in which the duration of a stimulus appears subjectively elongated immediately following a rapid movement, such as a saccadic eye movement or a manual action. This temporal overestimation creates the impression that the stimulus persists longer than it actually does, effectively extending the perceived onset of the stimulus backward in time to compensate for the perceptual gap during the movement. Saccades, the quick shifts of gaze between fixation points, serve as a common trigger for this effect. A primary example of chronostasis occurs when an observer looks away from a clock and then back at it just as the second hand is about to tick; the first observed position of the hand appears frozen in place, seeming to last up to 500 milliseconds longer than its actual brief duration. In experimental settings, participants making a to a visual target, such as a rotating clock hand or a flashing stimulus, report perceiving the target's initial presentation as extended, filling in the temporal void created by the . The illusion's magnitude typically ranges from 100 to 200 milliseconds of overestimation, though it can vary with the duration and of the preceding movement, and it manifests reliably after such movements but not during periods of static fixation. Unlike the stopped-motion effect, where apparent motion halts due to discrete frame sampling in visual displays, chronostasis specifically entails a temporal dilation linked to the onset of voluntary or reflexive actions, preserving perceptual continuity across the movement.

Historical Background

The stopped clock illusion, in which the second hand of an analog clock appears to pause momentarily upon shifting one's gaze to it, has long been recognized as a common perceptual experience, likely dating back centuries to the widespread use of mechanical timepieces. Scientific investigation of this phenomenon emerged in the late 1990s, transitioning from informal observations to systematic experimentation. In 1997, Peter Brown and John C. Rothwell reported initial findings at the , observing that the illusion occurs most reliably when a rapid () directs fixation to a immediately after the second hand advances, suggesting a link to oculomotor processes. Their work highlighted how the brain might compensate for the brief perceptual gap during saccades, though quantitative measures were not yet established. The term "chronostasis" was introduced in 2001 by Yarrow, Haggard, Brown, and Rothwell to encapsulate the illusory temporal extension or stasis following such eye movements, distinguishing it from broader distortions. By the early 2000s, researchers had developed controlled laboratory paradigms to study the effect more rigorously. In 2001, Kielan Yarrow, Patrick Haggard, and colleagues quantified the illusion using tasks involving self-paced to digital chronoscopes, demonstrating that post-saccadic stimuli are perceived as lasting approximately 100 milliseconds longer than actual, effectively backfilling the suppressed visual input during the eye shift to preserve perceptual continuity. These pre-2000s efforts shifted focus from anecdotal accounts to empirical methods, employing fixation crosses, auditory cues for saccade timing, and subjective duration judgments, while early links to attentional shifts were explored in related oculomotor studies.

Physiological and Neural Basis

Role of Eye Movements

Saccades are rapid, ballistic eye movements that abruptly shift the point of fixation from one location to another in the , enabling efficient scanning of the environment. These movements typically exhibit peak velocities ranging from 200 to 700 degrees per second, depending on their , and can be classified as voluntary (endogenous, such as self-paced shifts in ) or reflexive (exogenous, triggered by sudden peripheral stimuli). The chronostasis illusion is specifically triggered by the execution of a , with the perceptual time extension commencing at the moment the eyes land on the target stimulus following the movement. This temporal distortion is closely tied to the period of visual suppression during the itself, during which retinal blur occurs for approximately 50-100 milliseconds due to the high-speed eye rotation, effectively masking the transient disruption in visual input. Experimental evidence from fixation tasks underscores the essential role of eye movements, as chronostasis does not manifest when observers maintain a steady on the stimulus without performing a . In counter-movement paradigms, where the stimulus is passively shifted toward the fixation point without requiring active eye displacement, the is similarly absent, confirming that the effect depends on the motor act of the rather than mere stimulus change. The chronostasis effect exhibits a distinct temporal window, primarily observed for stimuli presented up to about 50 milliseconds after offset, with the extension decaying rapidly thereafter, which aligns with the 's need to maintain perceptual continuity across gaze shifts.

Perceptual and Neural Mechanisms

Chronostasis arises primarily through saccadic suppression, a neural process in which the actively inhibits visual processing during rapid eye movements to avoid perceiving motion blur from the shifting retinal image. This suppression begins approximately 50-100 ms before onset and persists for about 100-200 ms afterward, effectively creating a perceptual gap that the brain fills by reconstructing continuity. Key neural pathways involved in this process include the , which generates efferent signals for eye movements and contributes to triggering chronostasis via low-level subcortical mechanisms. These signals interact with higher cortical areas, such as the and parietal cortex (specifically the lateral intraparietal area), to correlate motor commands with perceptual remapping and maintain spatial stability across saccades. Perceptual reconstruction in chronostasis involves backdating the perceived onset of a post-saccadic stimulus to the start of the eye movement, an illusory extension of approximately 90-200 milliseconds facilitated by corollary discharge signals that predict sensory consequences of actions. This mechanism compensates for suppressed input by attributing the stimulus's appearance to a time before the saccade, preserving the subjective continuity of events despite the neural delay.

Variants Across Sensory and Motor Domains

Visual Chronostasis

Visual chronostasis manifests as a perceptual in which the duration of a visual stimulus presented immediately after a is subjectively overestimated, creating the impression that time has momentarily paused. In the classic experimental , participants fixate on a peripheral cue, which triggers a toward a central clock displaying a moving second hand. Upon landing the eyes on the clock, the second hand appears to remain stationary for an extended period before resuming its motion, as if the observer's gaze has "stopped" the clock. This effect, first systematically demonstrated in laboratory settings, highlights how the brain compensates for the brief disruption in visual input during the by extending the perceived onset of the post-saccadic stimulus backward in time. The applies particularly to dynamic visual stimuli, such as the sweeping needle of an analog clock or a moving cursor on a display, where the perceived pause is more pronounced than for static images. For instance, when saccading to a face, observers report the second hand as having advanced less than it actually has during the interval from saccade onset to fixation, with the magnitude of the distortion increasing for stimuli involving continuous motion, as the attributes the movement's continuity across the saccadic gap. This stimulus-specific enhancement underscores the role of perceived motion in amplifying the temporal extension, though the effect diminishes for non-moving or less salient elements. The visual chronostasis illusion is most robust when the post-saccadic stimulus lands in the fovea, the high-acuity central region of the , allowing for detailed processing that facilitates the perceptual . In contrast, stimuli perceived in the peripheral after the saccade exhibit a reduced effect, likely due to lower and attentional prioritization of foveal input, resulting in weaker temporal binding. serve as the primary trigger for this visual variant, linking it to oculomotor processes that maintain perceptual continuity. Recent studies (as of 2025) further show that while the initial post-saccadic stimulus is overestimated, subsequent events along the trajectory may be perceptually compressed, revealing opposing temporal distortions. Measurement of visual chronostasis typically relies on subjective reports of perceived duration or temporal order judgments, where participants compare the estimated time of the post-saccadic stimulus against a reference interval. In standard clock-hand tasks, observers indicate the hand's position at fixation onset, revealing an average overestimation of approximately 100-200 ms, equivalent to the second hand appearing frozen for that duration despite actual advancement. These methods, often employing psychophysical techniques like method of adjustment, provide quantitative insights into the illusion's scale while controlling for veridical timing cues.

Auditory and Multisensory Chronostasis

Auditory chronostasis refers to the perceptual overestimation of duration for auditory stimuli, analogous to the visual variant, but elicited through shifts in auditory attention rather than eye movements. In experiments where participants judged the length of a silent gap between two tones presented dichotically (one to each ear), switching attention from one ear to the other resulted in an overestimation of the gap duration by approximately 130 ms, with subjective estimates of a 1000 ms interval reduced to about 825 ms when attention shifted. This effect, though comparable in magnitude to visual chronostasis (typically 100-200 ms following saccades), is weaker and independent of overt motor actions like saccades, suggesting a shared multimodal mechanism for temporal perception that operates across sensory domains. Multisensory chronostasis arises when auditory and visual cues interact during or after saccades, modulating the through cross-modal integration. A synchronous auditory stimulus presented at the onset of a post-saccadic visual target reduces the magnitude of visual chronostasis by about 58 ms, with the effects of the saccade-induced dilation and auditory compression adding linearly to visual (model fit R = 0.962). This linear integration indicates that auditory signals dominate over visual ones in temporal processing during eye movements, with auditory cues carrying a higher relative weight (0.539) compared to saccadic effects (0.385). Such interactions highlight how non-visual inputs can counteract visual overestimation, compressing perceived temporal gaps by merging auditory onsets with post-saccadic visual events. These findings have implications for speech perception, where precise temporal alignment between auditory and visual cues is crucial; auditory dominance in multisensory chronostasis may help maintain perceptual continuity during rapid eye movements in dynamic environments like . Neural suppression during saccades, as observed in visual processing, likely extends to cross-modal binding, allowing the brain to fuse auditory and visual temporal signals for coherent perception. Manual chronostasis manifests as an overestimation of the duration of stimuli presented immediately after voluntary manual actions, such as or reaching toward an object. In a foundational experiment, participants actively reached to touch a tactile stimulus and subsequently overestimated the time their hand had been in contact with it by 90–120 ms relative to static conditions without movement. This temporal dilation arises from a perceptual backdating mechanism, where tactile is referred to a time preceding the actual physical contact, facilitating seamless integration of sensory input during the action. The strength of this illusion is closely tied to action intentionality, with greater overestimation occurring for self-initiated movements compared to static conditions. Self-generated manual actions generate internal predictive signals, such as efference copies of motor commands, which contribute to the backward extension of perceived time and enhance the 's magnitude. In contrast, of the limb—where movement is imposed without voluntary —results in minimal or absent dilation, as the lack of efferent signaling disrupts the predictive remapping of sensory events. Effector specificity plays a key role, with hand actions eliciting a consistent temporal dilation of approximately 100 ms, comparable to that observed in smaller saccadic eye movements but modulated by the precision demands of the limb. For instance, reaching gestures produce reliable overestimation regardless of reach extent (e.g., short reaches of ~250 ms vs. longer ones of ~370 ms), underscoring the role of motor planning in fine-grained manual control over coarser oculomotor shifts. This effect extends to visual stimuli following hand movements, where perceived duration expands for pointing actions directed away from the body, reflecting directional influences on motor preparation. Representative examples include adaptations of the clock illusion during voluntary finger shifts or head turns to fixate on a timepiece, where the initial second-hand movement appears prolonged by 100–200 ms post-action, distinct from scenarios involving static conditions that yield no such perceptual stretch. These manual variants highlight how intentional motor outputs bind temporal to action outcomes, briefly referencing broader concepts like temporal binding without relying on sensory inputs alone.

Modulating Factors

Oculomotor and Spatial Factors

Oculomotor factors play a central role in modulating the magnitude of visual chronostasis, particularly through properties of saccadic eye movements. The amplitude of a saccade, which determines its angular extent, directly influences the strength of the illusion. Larger saccades, such as those spanning 50° compared to 10°, result in a greater perceived temporal extension of the post-saccadic stimulus, with the bias increasing proportionally to the saccade's duration due to extended periods of visual suppression during the eye movement. This relationship arises because longer saccades prolong the phase of reduced visual sensitivity, leading to a more pronounced compensatory overestimation of the stimulus onset duration, typically on the order of 100-200 ms for standard experimental saccades around 10-20° in amplitude. Spatial continuity between pre- and post-saccadic visual scenes is essential for eliciting chronostasis, as disruptions to this continuity significantly attenuate the effect. The requires the post-saccadic stimulus to appear at the expected fixation point without noticeable displacement; for instance, if the target shifts by as little as 3° horizontally during the , the temporal dilation is eliminated, preventing the from attributing continuity across the movement. Such spatial disruptions, like gaps or jumps in the stimulus position, can reduce the effect by up to 50% or more, underscoring the role of stable spatial mapping in preserving perceptual continuity. The directionality of saccades also contributes to variations in chronostasis, with effects tied to mechanisms minimizing retinal slip and maintaining stable vision. Horizontal saccades tend to produce stronger illusions than vertical ones, as horizontal movements align more closely with typical scanning patterns and elicit greater suppression to counteract image motion across the retina. This asymmetry reflects the oculomotor system's prioritization of horizontal gaze shifts in everyday visual exploration, enhancing the temporal binding for stimuli encountered after such movements. Environmental layout further influences chronostasis by affecting the perception of spatial continuity in the . In cluttered backgrounds with multiple competing elements, the weakens because the post-saccadic stimulus competes for continuity attribution, reducing the perceived duration extension compared to sparse, uniform environments that facilitate seamless perceptual bridging. For example, the presence of a static second object in the display maintains the effect if it remains stable, but dynamic changes or visual noise in the background disrupt this, lowering the magnitude by emphasizing novelty over continuity.

Attentional and Cognitive Factors

Attention redirection plays a key role in modulating the chronostasis illusion, particularly through pre-saccade cues that direct focus to the saccade target. When participants receive exogenous or endogenous cues prior to initiating a saccade, the perceived duration of the post-saccadic stimulus is extended, with studies showing an enhancement of approximately 150 ms in temporal dilation at short stimulus-onset asynchronies (SOAs) of 100 ms, likely due to strengthened binding between the motor command and subsequent sensory input. This effect highlights how attentional allocation to the target location facilitates perceptual continuity across the eye movement, amplifying the illusion's magnitude compared to uncued conditions. Cognitive load from concurrent tasks significantly attenuates the chronostasis effect, indicating top-down attentional control as a modulator. In experiments involving dual-task paradigms, such as simultaneous timing judgments and secondary cognitive demands, the typical overestimation of post-saccadic duration is reduced by about 31 ms, with greater diminishment under high-load conditions like no-gap saccade paradigms where point of subjective equality (PSE) shifts from 460 ms to 415 ms. This suggests that divided attention disrupts the dedicated processing resources needed for temporal binding, supporting a role for executive functions in sustaining the illusion. Expectancy influences the strength of chronostasis, with intentional and predicted saccades producing larger temporal distortions than unexpected or reactive ones. Cued saccades, where participants anticipate the movement direction, result in backwards shifts in perceived onset reaching up to 150 ms prior to actual initiation, and overall expansions of 100–150 ms for longer SOAs (400–700 ms), contrasting with minimal effects in uncued scenarios. Intentional shifts thus amplify the dilation, consistent with predictive mechanisms that align motor efference copies with sensory expectations to maintain temporal continuity.

Stimulus and Environmental Factors

Stimulus properties significantly influence the magnitude of chronostasis. Duration and intensity of the stimulus also modulate chronostasis. Short-duration stimuli, particularly those under 1 second with high salience, maximize the illusion by aligning with the temporal window of post-saccadic integration, where overestimation is most pronounced. Differences across sensory domains highlight varying sensitivities to stimulus attributes. By contrast, visual chronostasis shows less dependence on shape attributes, prioritizing and motion over form.

Theoretical Explanations

Continuity and Filling-In Hypotheses

The continuity hypothesis proposes that chronostasis functions to preserve perceptual seamlessness during saccadic eye movements by antedating the perceived onset of post-saccadic stimuli to a moment just prior to saccade initiation, thereby extending the subjective duration of the pre-saccadic fixation and bridging the temporal discontinuity caused by saccadic suppression. This mechanism relies on extraretinal signals, such as efference copies of the motor command, to align sensory with the brain's internal timeline, ensuring a continuous flow of visual experience despite the ~200-300 ms period of degraded input during the saccade. Seminal work by Yarrow et al. (2001) demonstrated this through the stopped-clock illusion, where the first post-saccadic second hand position appears frozen for an additional ~100-200 ms, scaling with saccade amplitude to compensate for larger gaps in longer movements. Supporting evidence includes the invariance of chronostasis across saccade categories—from voluntary self-timed saccades to reflexive express s—indicating a low-level, subcortical efferent trigger rather than higher cognitive processes. Yarrow, Johnson, Haggard, and Rothwell (2004) further showed consistent effects in experiments varying saccade context, reinforcing that the resolves perceptual discontinuities inherent to rapid, ballistic eye shifts. Notably, chronostasis is absent during eye movements, where continuous visual tracking avoids suppression and temporal gaps, highlighting its specificity to saccadic disruptions. The filling-in process complements continuity by interpolating "missing" temporal information via extraretinal cues, without altering spatial perception, to mask awareness of saccadic suppression and maintain subjective temporal coherence. In this view, the brain retrospectively attributes extended duration to the post-saccadic stimulus based on pre-saccadic content, dissociating time perception from motion trajectories; for instance, observers perceive a stationary clock hand as paused at its new position rather than filling in a moving path. This temporal adjustment, rather than literal sensory filling, aligns with findings that chronostasis persists even when spatial continuity is compromised, emphasizing a purely durational compensation. However, these hypotheses face limitations in explaining multisensory chronostasis, where auditory or tactile variants exhibit forward shifts in perceived timing rather than backward antedating, suggesting more complex cross-modal integration beyond visual continuity mechanisms. Additionally, while neural suppression during saccades provides a foundational gap for filling-in, the precise subcortical loci (e.g., ) remain speculative without direct causal evidence.

Temporal Binding and Prediction Models

Temporal binding refers to the perceptual compression of the interval between a voluntary action and its sensory outcome, creating a subjective sense of causal linkage. In the context of chronostasis, this phenomenon manifests as a form of action-backdating, where the perceived onset of the post-movement stimulus is shifted earlier to align with the action, thereby binding the two events temporally. A 2020 study demonstrated this through experiments contrasting saccadic chronostasis with intentional binding in keypress tasks, finding that while keypresses compressed action-effect intervals by approximately 87-141 ms, saccades instead produced dilation without equivalent binding, suggesting backdating as a mechanism to maintain perceived continuity. Prediction models posit that the employs forward models to anticipate sensory consequences of movements, generating internal expectations that influence temporal . These models allow the to predict post-movement stimuli based on motor plans, leading to an overestimation of stimulus duration if the actual sensory input deviates from the , as seen in chronostasis where the first fixated stimulus appears prolonged to match the anticipated timeline. This anticipatory process integrates efference copies—internal signals of motor commands—with sensory feedback to optimize during action. The plays a central role by conveying motor command details to sensory areas, establishing temporal expectations that trigger the chronostasis . Specifically, these copies generate predictions about when post-saccadic stimuli should appear, resulting in a perceived backward shift of the stimulus onset by approximately 50 ms relative to the actual timing, across various types, including self-timed and reflexive variants, supporting a subcortical origin for this efference signal, likely from the , ensuring consistent illusion magnitude. These mechanisms extend to manual chronostasis, where tactile of a touched object is backdated to precede physical contact, mirroring visual effects through similar efference-based during arm movements. Additionally, external cues such as synchronous sounds can reduce the illusion's magnitude by providing alternative temporal anchors that override motor-derived , as shown in tasks where auditory stimuli diminished visual chronostasis by integrating cross-modal information. This highlights how environmental factors modulate binding and processes.

Experimental Evidence and Recent Developments

Classic Experiments

One of the foundational experiments demonstrating chronostasis involved participants making voluntary saccades to a visual clock displaying a moving second hand. In this paradigm, observers fixated on a peripheral target before saccading to the clock, after which they reported the perceived position of the second hand at the moment of fixation landing, often via a press to indicate the timing. The results showed a consistent overestimation of the duration for which the clock hand appeared stationary, averaging approximately 150 ms longer than the actual physical time elapsed. Building on this setup, subsequent studies varied the amplitude and type (e.g., pro- vs. ) of to examine the 's specificity to oculomotor parameters. Participants executed across horizontal directions toward the clock target, with eye movements precisely monitored to ensure accurate landing on the fixation point. The chronostasis effect persisted across types but was strongest when the precisely terminated on the target, confirming that the illusion depends on the post-saccadic fixation rather than the trajectory alone. Early investigations into the role of further clarified that chronostasis requires an actual change, not merely an attentional shift. In experiments from the early , participants shifted covert to a peripheral clock without moving their eyes, using cues to direct focus while maintaining central fixation. No temporal overestimation occurred in these conditions, distinguishing the effect from attentional mechanisms alone. Methodological rigor in these classic studies relied on precise eye-tracking systems, such as video-based trackers, to record onset, duration, and landing accuracy, ensuring that only valid trials with clean eye movements were analyzed. Subjective was quantified using scaling methods, where participants estimated durations relative to reference intervals or adjusted stimuli to match perceived onset times. Additionally, trials contaminated by microsaccades—small involuntary fixational movements—were excluded through post-hoc analysis of eye position data to prevent confounding the -induced effect.

Contemporary Research Findings

Recent research has explored the influence of action on chronostasis, demonstrating differences in the illusion's magnitude based on action intentionality and effector choice. A 2020 study compared keypress and actions, varying their intentionality, and found stronger temporal expansion for cued saccades compared to self-initiated ones, and temporal compression (intentional binding) for keypress actions, supporting theories of efferent signals in perceptual binding. Multisensory interactions have also been examined, revealing how auditory cues modulate visual chronostasis. In a 2023 experiment, synchronous sounds presented during saccades linearly reduced the perceived duration of the post-saccadic visual stimulus, indicating additive effects between saccadic suppression and auditory influences on time perception, with broader implications for audiovisual integration in dynamic environments. Advancements in understanding saccade-induced distortions continued into 2025, with studies showing that saccades not only prolong the first post-movement stimulus (consistent with chronostasis) but also compress the of subsequent stimuli, creating opposing temporal effects. These findings highlight a brief, uneven attentional distribution following eye movements, applicable to both oculomotor and manual action variants where similar perceptual consistencies emerge across movement categories. Emerging trends integrate chronostasis into (VR) contexts, where saccadic illusions persist and influence during immersive tasks. A 2024 investigation showed that rhythmic auditory stimuli in VR can modulate general subjective timing in immersive tasks, suggesting applications for designing more natural temporal experiences in simulated environments to mitigate perceptual distortions.

References

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  2. https://pmc.ncbi.nlm.nih.gov/articles/PMC1266050/
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  4. https://pubmed.ncbi.nlm.nih.gov/12842013/
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  6. https://pubmed.ncbi.nlm.nih.gov/11713528/
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