Clock Hand Research Articles

Quantifying the Transition from Unconscious to Conscious Detection of Temporal Patterns in Vigilance Tasks: A Unique Adaptation of Mackworth's Clock Test.

This study investigates the cognitive mechanisms underlying vigilance and pattern recognition using a novel adaptation of Mackworth's Clock Test. We aimed to quantify the time it takes for temporal patterns detected unconsciously through implicit learning to surface in the conscious mind within a dynamic vigilance task environment. Forty-eight participants detected random and non-disclosed rhythmic anomalous clock hand movements in this setting. Our results indicate significant variability in detection accuracy, reaction times, and the ability to recognize the hidden pattern among participants. Notably, 23% of all participants and 56% of those who consciously reported the pattern exhibited statistically lower reaction times indicative of knowledge of the pattern 40 s before conscious identification. These findings provide valuable insights into the transition from unconscious to conscious detection, highlighting the complexity of sustained attention and pattern recognition. The study's implications extend to designing training programs and tasks for high-stakes professions requiring prolonged vigilance. Future research should further explore the cognitive and neural correlates of these processes and the impact of task complexity on performance.

Switching between task control modes incurs greater reprogramming costs than programming the response de novo

When performing synchronous hand and foot movements, the way the limbs are synchronized differs depending on the mode of control. When performed in a reaction time (RT) paradigm (reactive control), EMG onsets become synchronized resulting in asynchronous displacement onset. However, when the same movement is performed as an anticipation-timing task (predictive control), displacement onset is synchronized by unconsciously introducing a small delay between EMG onsets. The present experiment investigated the reprogramming costs associated with switching between predictive and reaction control modes. Participants (N = 12, 6F) were asked to simultaneously lift their right heel and right hand in an anticipation-timing task when a rotating clock hand reached a specified target. On some trials, an auditory stimulus was presented either 250 ms or 500 ms before the target and participants were instructed to execute the synchronous movement as quickly as possible after the signal (i.e., switch to reactive mode). Results showed that when the auditory stimulus was delivered 250 ms before the target, participants were unable to switch to a reactive control mode but did switch when the auditory stimulus was presented 500 ms before the target. As expected, the RT on switch trials was substantially longer (∼230 ms) than a simple RT control condition but was also significantly longer (∼130 ms) than a choice RT control condition. These results indicate that switching between control modes for a task involving the same musculature incurs reprogramming costs that are even greater than the time required to program the response de novo.

Object Motion Manipulation and time perception in virtual reality

This paper presents a novel approach to altering how time is perceived in Virtual Reality (VR). It involves manipulating the speed and pattern of motion in objects associated with timekeeping, both directly (such as clocks) and indirectly (like pendulums). Objects influencing our perception of time are called ‘zeitgebers‘; for instance, observing a clock or pendulum tends to affect how we perceive the passage of time. The speed of motion of their internal parts (clock hands or pendulum rings) is explicitly or implicitly related to the perception of time. However, the perceptual effects of accelerating or decelerating the speed of a virtual clock or pendulum in VR is still an open question. We hypothesize that the acceleration of their internal motion will accelerate the passage of time and that the irregularity of the orbit pendulum’s motion will amplify this effect. We anticipate that the irregular movements of the pendulum will lower boredom and heighten attention, thereby making time seem to pass more quickly. Therefore, we conducted an experiment with 32 participants, exposing them to two types of virtual zeitgebers exhibiting both regular and irregular motions. These were a virtual clock and an orbit pendulum, each operating at slow, normal, and fast speeds. Our results revealed that time passed by faster when participants observed virtual zeitgebers in the fast speed condition than in the slow speed condition. The orbit pendulum significantly accelerated the perceived passage of time compared to the clock. We believe that the irregular motion requires a higher degree of attention, which is confirmed by the significantly longer gaze fixations of the participants. These findings are crucial for time perception manipulation in VR, offering potential for innovative treatments for conditions like depression and improving wellbeing. Yet, further clinical research is needed to confirm these applications.

A spatial-attentional mechanism underlies action-related distortions of time judgment

Temporal binding has been understood as an illusion in timing judgment. When an action triggers an outcome (e.g. a sound) after a brief delay, the action is reported to occur later than if the outcome does not occur, and the outcome is reported to occur earlier than a similar outcome not caused by an action. We show here that an attention mechanism underlies the seeming illusion of timing judgment. In one method, participants watch a rotating clock hand and report event times by noting the clock hand position when the event occurs. We find that visual spatial attention is critically involved in shaping event time reports made in this way. This occurs because action and outcome events result in shifts of attention around the clock rim, thereby biasing the perceived location of the clock hand. Using a probe detection task to measure attention, we show a difference in the distribution of visual spatial attention between a single-event condition (sound only or action only) and a two-event agency condition (action plus sound). Participants accordingly report the timing of the same event (the sound or the action) differently in the two conditions: spatial attentional shifts masquerading as temporal binding. Furthermore, computational modeling based on the attention measure can reproduce the temporal binding effect. Studies that use time judgment as an implicit marker of voluntary agency should first discount the artefactual changes in event timing reports that actually reflect differences in spatial attention. The study also has important implications for related results in mental chronometry obtained with the clock-like method since Wundt, as attention may well be a critical confounding factor in the interpretation of these studies.

A spatial-attentional mechanism underlies action-related distortions of time judgment.

Temporal binding has been understood as an illusion in timing judgment. When an action triggers an outcome (e.g. a sound) after a brief delay, the action is reported to occur later than if the outcome does not occur, and the outcome is reported to occur earlier than a similar outcome not caused by an action. We show here that an attention mechanism underlies the seeming illusion of timing judgment. In one method, participants watch a rotating clock hand and report event times by noting the clock hand position when the event occurs. We find that visual spatial attention is critically involved in shaping event time reports made in this way. This occurs because action and outcome events result in shifts of attention around the clock rim, thereby biasing the perceived location of the clock hand. Using a probe detection task to measure attention, we show a difference in the distribution of visual spatial attention between a single-event condition (sound only or action only) and a two-event agency condition (action plus sound). Participants accordingly report the timing of the same event (the sound or the action) differently in the two conditions: spatial attentional shifts masquerading as temporal binding. Furthermore, computational modeling based on the attention measure can reproduce the temporal binding effect. Studies that use time judgment as an implicit marker of voluntary agency should first discount the artefactual changes in event timing reports that actually reflect differences in spatial attention. The study also has important implications for related results in mental chronometry obtained with the clock-like method since Wundt, as attention may well be a critical confounding factor in the interpretation of these studies.

A Telemedicine Analytic Framework for Fully and Semi-automatic Alzheimer's Disease Screening using Clock Drawing Test.

More than 6 million Americans are at risk for Alzheimer's Disease Related Dementias (ADRD), most of whom are 65 or older. The clock drawing test (CDT) is a quick, simple, and effective technique that has the potential advantage of self-management and screening for ADRD patients. Current CDT-based ADRD screening studies focus more on efficacy, involving many handcrafted features, ignoring data modalities, and lacking validation. This paper aims to propose a unified telemedicine framework for fully and semi-automatic effective early ADRD screening based on multimodal and agile data fusion, focusing on the interpretability and validation of the model by using gradient-weighted class activation mapping (Grad-CAM) and locally linear embedding (LLE). The datasets for this work include 1,662 samples of CDT images and related demographic and cognitive information. The fully automatic case involving only CDT images can achieve the highest AUC of 81% with a 75% recall rate in binary screening. The multimodal data fusion in the semi-automatic case can achieve up to 90% AUC with an 83% recall rate. The visualization of the Convolutional Neural Networks (CNN) shows that it can automatically obtain critical information about the outline, scale, and clock hands from CDT images, and the analysis of structured features shows that the memory test is key to effective ADRD screening.

Clock Drawing Test: Types of Errors and Accuracy in Early Cognitive Screening.

Clock Drawing Test (CDT) is a commonly used screening tool for cognitive disorders, known for its ease of administration and scoring. Despite frequent use by clinicians, CDT is criticized for its poor predictive value in mild cases of impairment. To evaluate CDT as a screening tool for early stage of cognitive impairment in biomarker-verified Alzheimer's disease (AD) and depressive disorder (DD). We analyzed CDT of 172 patients with verified AD, 70 patients with DD, in whom neurodegenerative disorder was excluded using cerebrospinal fluid biomarkers, and 58 healthy older adults. CDT was scored using the semi-quantitative (Shulman) and itemized criteria (adapted from Mendez). Logistic regression showed that for both DD and AD patients with high Mini-Mental State Examination (MMSE) scores (27 and above) the significant predicting variable is uneven number spacing. As MMSE deteriorates (24-26 points), an additional error of setting clock hands is predictive of the disease. In the low MMSE condition, CDT showed an acceptable discrimination for AD (AUC itemized 0.740, Shulman 0.741) and DD (AUC itemized 0.827, Shulman 0.739) using both scoring methods. In the high MMSE condition, discrimination rates were acceptable using itemized scoring but poor using Shulman scoring for both AD (AUC itemized 0.707, Shulman 0.677) and DD (AUC itemized 0.755, Shulman 0.667) groups. Ideally, modern diagnostic process should take place before the cognitive performance drops beneath the healthy range. This makes CDT of little use when screening patients with very mild cognitive deficits.

An event-termination cue causes perceived time to dilate.

The perceived duration of time does not veridically reflect the physical duration but is distorted by various factors, such as the stimulus magnitude or the observer's emotional state. Here, we showed that knowledge about an event's termination time is another significant factor. We often experience time passage differently when we know that an event will terminate soon. To quantify this, we asked 33 university students to report a rotating clock hand's duration with or without a termination cue that indicated the position at which the clock hand disappeared. The results showed that the presence of the termination cue dilated perceived durations, and the dilating effect was larger when the stimulus duration was longer, or the speed of the rotating stimulus was slower. A control experiment with a start-cue excluded the possibility that the cue's mere existence caused the results. Further computational analyses based on the attention theory-of-time perception revealed that the size of dilation is best explained by neither an event's duration nor the distance traveled by the clock hand, but by how long the clock hand spends time near the termination cue. The results imply that an event-termination cue generates a field in which the perceived time dilates.

Clock Drawing Test Performance of Young Adults Based on a One-Shot Case Study.

The clock drawing test (CDT) is being used regularly by medical professionals in a variety of settings to aid in assessing cognitive functioning in adults of all ages. As our technological environment has changed significantly, because of the inception of this measure, the use of and exposure to the analog clock have diminished. We investigated whether young adults, who have grown up in a mainly digital world, can draw and tell time on an analog clock. Participants aged 18-30years (N = 80, Mage = 24.2, SD = 3.93), who self-identified as having normal cognition, completed the CDT, as well as setting hands on a pre-drawn clock and identifying analog clock times. About 25% of participants received a CDT score below the expected range. There was a moderate, positive correlation between analog clock hand setting and time identification in the group who scored below the expected range on the CDT only (rs(16) = 0.472, p = .048). Most participants reported not wearing an analog watch. Based on these findings, the CDT should be used with caution to screen cognitive functioning in young adults (i.e., aged 18-30 years). Consideration of an alternative approach to screening cognition and modifying cognitive assessments in which the CDT is embedded is recommended for this population. These findings warrant further investigation into CDT performance in the young adult population.

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

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

Explainable automated evaluation of the clock drawing task for memory impairment screening.

The clock drawing task (CDT) is frequently used to aid in detecting cognitive impairment, but current scoring techniques are time-consuming and miss relevant features, justifying the creation of an automated quantitative scoring approach. We used computer vision methods to analyze the stored scanned images (N=7,109), and an intelligent system was created to examine these files in a study of aging World Trade Center responders. Outcomes were CDT, Montreal Cognitive Assessment (MoCA) score, and incidence of mild cognitive impairment (MCI). The system accurately distinguished between previously scored CDTs in three CDT scoring categories: contour (accuracy=92.2%), digits (accuracy=89.1%), and clock hands (accuracy=69.1%). The system reliably predicted MoCA score with CDT scores removed. Predictive analyses of the incidence of MCI at follow-up outperformed human-assigned CDT scores. We created an automated scoring method using scanned and stored CDTs that provided additional information that might not be considered in human scoring.

Time perception and pain: Can a temporal illusion reduce the intensity of pain?

It is commonly known-and previous studies have indicated-that time appears to last longer during unpleasant situations. This study examined whether a reciprocal statement can be made-that is, whether changes in the perception of time can influence our judgment (or rating) of a negative event. We used a temporal illusion method (Pomares et al. Pain152, 230-234,2011) to induce distortions in the perception of time. Two stimuli were presented for a constant time: a full clock, which stayed on the screen until its clock hand completed a full rotation (360°); and a short clock, in which the clock hand moved just three-quarters of the way (270°), thus suggesting a reduced interval duration. However, both stimuli were shown for the same amount of time. We specifically investigated (a) whether we could induce a temporal illusion with this simple visual manipulation, and (b) whether this illusion could change participants' ratings of a painful stimulus. In Experiment I(n = 22), to answer (a) above, participants were asked to reproduce the duration in which the different clocks were presented. In Experiment II(n = 30), a painful thermal stimulation was applied on participants' hands while the clocks were shown. Participants were asked to rate the perceived intensity of their pain, and to reproduce its duration. Results showed that, for both experiments, participants reproduced a longer interval after watching the full clock compared with the short clock, confirming that the clock manipulation was able to induce a temporal illusion. Furthermore, the second experiment showed that participants rated the thermal stimuli as less painful when delivered with the short clock than with the full clock. These findings suggest that temporal distortions can modulate the experience of pain.

Distinguishing guesses from fuzzy memories: Further evidence for item limits in visual working memory.

There is consistent debate over whether capacity in working memory (WM) is subject to an item limit, or whether an unlimited number of items can be held in this online memory system. The item limit hypothesis clearly predicts guessing responses when capacity is exceeded, and proponents of this view have highlighted evidence for guessing in visual working memory tasks. Nevertheless, various models that deny item limits can explain the same empirical patterns by asserting extremely low fidelity representations that cannot be distinguished from guesses. To address this ambiguity, we employed a task for which guess responses elicited a qualitatively distinct pattern from low fidelity memories. Inspired by work from Rouder et al. (2014), we employed an orientation WM task that required subjects to recall the precise orientation of each of six memoranda presented 1 s earlier. The orientation stimuli were created by rotating the position of a "clock hand" inside a circular region that was demarcated by four colored quadrants. Critically, when observers guess with these stimuli, the distribution of responses is biased towards the center of these quadrants, creating a "banded" pattern that cannot be explained by a low precision memory. We confirmed the presence of this guessing pattern using formal model comparisons, and we show that the prevalence of this pattern matches observers' own reports of when they thought they were guessing. Thus, these findings provide further evidence for guessing behaviors predicted by item limit models of WM capacity.

Manipulations of Libet clock parameters affect intention timing awareness

W judgments are a widely used intention timing awareness estimate. These judgments are typically obtained by using the classic Libet-style paradigm whereby participants are asked to estimate the time they become aware of their intention to act by using the location of a rotating object on a clock face. There is an inconsistency in the Libet clock parameters used in previous studies, and it is unclear whether this variability impacts W judgments and other outcome measures, with implications for the construct validity of this measure and the generalisability of results across studies. Here, we present a four-experiment study that systematically manipulated the Libet clock speed, number of clock markings, length of the clock hand and type of clock radius in order to examine whether these parameter manipulations affect intention timing awareness estimates. Our results demonstrate W judgments can be significantly influenced by the clock speed and number of clock markings. The meaning and implications of these results are discussed.

First demonstration of a roller-driven timestamp mechanism for long-duration observations with high time resolution using large-area emulsion films

Abstract A multi-stage shifter allows timestamped measurements by emulsion films, which have a thin medium and high resolution (< 1μm). Using multiple layers of emulsion films that move at different speeds like hands of an analog clock, the shifter can create a unique positional displacement with respect to the time-track recorded. The time information of each track is obtained by reproducing each positional displacement by track reconstruction. We developed a new model of shifter with a lighter structure to enable a large aperture area and long-duration observation times by adding more layers. Operational testing suggested that the new shifter has a sub-second time resolution, which allows an emulsion gamma-ray telescope to obtain an imaging resolution within 1° (> 80 MeV), like previous balloon experiments. Furthermore, by adding a layer which move at 100 μm s-1, it achieved the 0.1 s time resolution required for high-resolution imaging above 1 GeV. We also found the possibilities of an almost three-fold improvement in the spatial resolutions in track reconstruction compared with the conventional model and of achieving time resolution on a scale of tens of milliseconds, which would enable phase resolution of a pulsar.

Longitudinal measurement properties of the Montreal Cognitive Assessment

ABSTRACT Introduction The Montreal Cognitive Assessment (MoCA) has started to be used in longitudinal investigations to measure cognition trends but its measurement properties over time are largely unknown. This study aimed to examine the longitudinal measurement invariance of individual MoCA items. Method We used four waves of data collected between 2014 and 2017 from a cohort study on health and well-being of older adults from twelve public housing estates in Hong Kong. We identified people aged 65 years or older at baseline who answered the MoCA items across all time points and had a valid indicator of educational level. A total of 1028 participants were included. We applied confirmatory factor analysis of ordinal variables to examine measurement invariance of the Chinese (Cantonese) MoCA (version 7.0) items across four time points, stratified by educational level, where invariant items were identified by sequential model comparisons. Results Four items exhibited a lack of measurement invariance across the four time points in both education groups (Clock Hand, abstraction, Delayed Recall, and Orientation). The items Cube and Sentence Repetition lacked longitudinal measurement invariance only in the “some education” group and the items Clock Shape and Clock Number only in the “no education” group. However, accounting for the lack of measurement invariance did not substantially affect classification properties for major neurocognitive disorder and mild cognitive impairment. Conclusions Our findings support using MoCA to assess changes in cognition over time in the study population while calling for future research in other populations.

Nazwy temporalne w gwarach kujawskich

The subject of research in this article are temporal names associated with relative time, occurring in the Kujawy dialects. The research material comes from the Dictionary of dialect and culture of Kujawy and its extensive – numbering several thousand dictionary entries – file. The purpose of the analysis is to describe their motivations and meanings. A review of the names shows that native terms dominate, and that time by the Kujawiaks was not understood as a physical quantity regulated by clock hands. People living according to the rhythm of the seasons, days, liturgical calendar, used temporal names resulting from the observation of repetitive natural phenomena and related to church holidays and annual customs important for their community.

Blue Stragglers as Tracers of the Dynamical State of Two Clusters in the Small Magellanic Cloud: NGC 339 and NGC 419

Abstract The level of central segregation of Blue Straggler stars has proved to be an excellent tracer of the dynamical evolution of old star clusters (the so-called “dynamical clock”), both in the Milky Way and in the Large Magellanic Cloud. The A + parameter, used to measure the Blue Stragglers degree of segregation, has in fact been found to strongly correlate with the parent cluster central relaxation time. Here, we have studied the Blue Straggler population of two young stellar systems in the Small Magellanic Cloud, namely NGC 339 (which is 6 Gyr old) and NGC 419 (with an age of only 1.5 Gyr), in order to study their dynamical state. Thanks to multi-epoch, high angular resolution Hubble Space Telescope observations available for both clusters, we took advantage of the stellar proper motions measured in the regions of the two systems and we selected a population of likely cluster members, removing the strong contamination from Small Magellanic Cloud stars. This enabled us to study, with unprecedented accuracy, the radial distribution of Blue Stragglers in these two extra-Galactic clusters and to measure their dynamical age. As expected for such young clusters, we found that both systems are poorly evolved from the dynamical point of view, also fully confirming that the A + parameter is a sensitive “clock hand” even in the dynamically young regime.

Improved sprinkler irrigation layouts for smallholders

Pressurized irrigation systems are economically justifiable for medium- to large-scale farms, while fewer choices are available for smallholders. The current research work provides additional options for small plots, as the only income source for low-income farmers in poorer countries, which produce a considerable portion of the agricultural products in some regions of the world. In this research, two novel layouts of a semipermanent sprinkler irrigation system, namely, clock hand (CH) and corner pivot (CP) lateral designs, were designed for a lighter irrigation system to lower the cost requirement. The new techniques were based on a quadrant/full circle movement pattern of manually pivoting laterals, with no/shorter main pipe requirements, which causes a higher system efficiency. These retrofitted layouts were examined in different farms with areas of 0.20 hm2, 0.81 hm2, 1.62 hm2, and 3.24 hm2 in Guangxi, China. This study introduced, analyzed, and compared the layouts with the widespread traditional split lateral method on technical planning, components, implementation, operation details, size optimization, performance evaluation, and economic advantages. In comparison with the traditional system, CH and CP were found to be more user-friendly and cost-effective but slightly complicated in design with higher required manual work. The results revealed a distribution uniformity (LQDU) of 81.0% to 84.0% via the catch can method, lower capital costs (35.0%-45.0%), and lower annual expenses (6.5%-9.8%) for CP and CH, respectively, compared to the split lateral method. The 0.81 hm2 and 1.62 hm2 farms were found to be the optimum farm sizes for implementation of the new methods for a 25-year project time horizon. The outcomes of this experimental work can encourage small farm owners with limited capital to apply pressurized systems for efficient irrigation and water resource sustainability. Keywords: sprinkler irrigation layout, semipermanent, smallholder, cost-effectiveness DOI: 10.25165/j.ijabe.20221502.6363 Citation: Rad S, Gan L, Dai J F, Zhang S P, Huang L L, Pan L Y, et al. Improved sprinkler irrigation layouts for smallholders. Int J Agric & Biol Eng, 2022; 15(2): 30–38.

Longitudinal Measurement Properties of the Montreal Cognitive Assessment

Background: The Montreal Cognitive Assessment (MoCA) has started to be widely used in longitudinal investigations to measure changes in cognition. However, the longitudinal measurement properties of MoCA have not been investigated. We aimed to examine the measurement invariance of individual MoCA items across four time points. Methods: We used longitudinal data collected between 2014 and 2017 from a cohort study on health and well-being of older adults in Hong Kong. The Cantonese version of the MoCA was used. We applied multiple group confirmatory factor analysis of ordinal variables to examine measurement invariance by educational level and across time points. Invariant items were identified by sequential model comparisons. Results: We included 1029 participants that answered MoCA items across all time points. We found that items Cube, Clock Hand and Clock Number had significantly different item parameters between participants with and without formal education at all time points. The selected model (RMSEA=0.031; SRMR=0.064) indicated that eight items (Trail, Cube, Clock Shape, Clock Number, Clock Hand, ion, Short-term Memory, and Orientation) did not exhibit measurement invariance over time. However, the differences in item parameter estimate over time were marginal. Accounting for the lack of measurement invariance did not substantially affect classification properties based on cutoff values at the 2nd ( major neurocognitive disorder) and 7th (mild cognitive impairment) percentile. Conclusion: Our findings support using MoCA to assess changes in cognition over time in the study population. Future research should examine the longitudinal measurement properties of the test in other populations with different characteristics.