Contextual influences of dimension, speed, and direction of motion on subjective time perception

Research has indicated that the direction of motion and the speed of motion can influence the subjective estimates of temporal duration of two-dimensional (2-D) stimuli expanding and contracting within the picture plane. In this study, we investigated whether the contextual cues of stimulus/movement-plane dimensionality (2-D stimuli with implied movement in the picture plane or depth-rendered “3-D” stimuli with implied movement in the depth plane) influence and interact with speed and implied movement direction during interval estimation. Participants viewed a series of standard stimulus durations followed by a test stimulus duration and determined whether the test and standard durations differed. The results indicated that moving stimuli were overestimated relative to stationary stimuli, regardless of the direction of motion or dimensionality. Also, faster-moving stimuli were overestimated relative to slower-moving stimuli. Importantly, an interaction between movement direction and dimensional cues indicated that the loom/recede distinction occurs for 2-D but not for 3-D stimuli. It is possible that the loom/recede distinction for the 2-D condition may be an artifact arising from reduced or from a lack of perceived motion in 2-D “recede” conditions, rather than a specific overestimation for looming stimuli.     

Action, arousal, and subjective time

Saccadic chronostasis refers to the subjective temporal lengthening of the first visual stimulus perceived after an eye movement. It has been quantified using a duration discrimination task. Most models of human duration discrimination hypothesise an internal clock. These models could explain chronostasis as a transient increase in internal clock speed due to arousal following a saccade, leading to temporal overestimation. Two experiments are described which addressed this hypothesis by parametrically varying the duration of the stimuli that are being judged. Changes in internal clock speed predict chronostasis effects proportional to stimulus duration. No evidence for proportionality was found. Two further experiments assessed the appropriateness of the control conditions employed. Results indicated that the chronostasis effect is constant across a wide range of stimulus durations and does not reflect the pattern of visual stimulation experienced during a saccade, suggesting that arousal is not critical. Instead, alternative processes, such as one affecting the onset of timing (i.e., the time of internal clock switch closure) are implicated. Further research is required to select between these alternatives.     

Agency, subjective time, and other minds

Intentional binding refers to a temporal attraction in the perceived times of actions and effects. So far, it has solely been investigated using judgments of the perceived time of actions or their effects. The authors report 3 experiments using an alternative method: the estimation of a time interval between a voluntary action and its subsequent effect. Interval estimates were obtained for intervals bounded by different kinds of actions and effects: The actions were either performed by the participants themselves or by the experimenter. The effects, in turn, were movements either applied to the body of the participant or to the experimenter. First, the results validated interval estimation as a method for exploring action awareness. Second, intentional binding was stronger for self-generated compared with observed actions, indicating that private information about the action contributes to action awareness. In contrast, intentional binding did not depend on whether a somatic effect was applied to the participant's or to another person's body. Third, for self-generated actions, external events gave rise to a stronger intentional binding than did somatic effects. This finding indicates that intentional binding especially links actions with their consequences in the external world.     

Decision time,subjective probability,and task difficulty

This study analyzed the relationships between decision time, subjective probability, and task difficulty in the context of a probability assessment task involving memory search. The results indicate that decision time and subjective probability do not yield identical functions. Also, decision time increases as subjective task difficulty increases. A similar relationship obtains between decision time and a measure of objective task difficulty. These latter two findings are inconsistent with Hogarth’s (1975) prediction of a nonmonotonic relationship between decision time and task difficulty.     

Happiness, time consciousness, and subjective life expectancy.

84 men and 141 women enrolled at a university reported their sexes and ages, rated their happiness and their time consciousness, and estimated how many more years they expected to live. Men significantly overestimated their subjective life span compared to actuarial data. Women (but not men) who were happier tended to be younger, had greater subjective life expectancies, and felt that they had lived a smaller percentage of their total lives. Both older men and older women tended to be more time conscious.     

Detection of changes in speed and direction of motion: Reaction time analysis

Observers reacted to the change in the movement of a random-dot field whose initial velocity,V _o, was constant for a random period and then switched abruptly to another value,V ₁. The two movements, both horizontally oriented, were either in the same direction (speed increments or decrements), or in the opposite direction but equal in speed (direction reversals). One of the two velocities,V ₀ orV ₁, could be zero (motion onset and offset, respectively). in the range of speeds used, 0–16 deg/sec (dps), the mean reaction time (MRT) for a given value ofV ₀ depended on |V ₁-V ₀| only: MRT ≈r +c(V ₀/|V ₁ ?V ₀|) ^β , where β=2/3,r is a velocity-independent component of MRT, andc(V ₀) is a parameter whose value is constant for low values ofV ₀ (0–4 dps), and increases beginning with some value ofV ₀ between 4 and 8 dps. These and other data reviewed in the paper are accounted for by a model in which the time-position function of a moving target is encoded by mass activation of a network of Reichardt-type encoders. Motion-onset detection (V ₀=0) is achieved by weighted temporal summation of the outputs of this network, the weights assigned to activated encoders being proportional to their squared spatial spans. By means of a “subtractive normalization,” the visual system effectively reduces the detection of velocity changes (a change fromV ₀ toV ₁) to the detection of motion onset (a change from 0 toV ₁-V ₀). Subtractive normalization operates by readjustment of weights: the weights of all encoders are amplified or attenuated depending on their spatial spans, temporal spans, and the initial velocityV ₀. Assignment of weights and weighted temporal summation are thought of as special-purpose computations performed on the dynamic array of activations in the motion-encoding network, without affecting the activations themselves.     

How changes in subjective general health predict future time perspective,and development and generativity motives over the lifespan

In this study, we used the lifespan theories of selection optimization and compensation (SOC) and the socio‐emotional selectivity theory (SST) to integrate the disengagement and activity perspectives on aging and to explain intra‐individual changes in work motivation. A two‐wave longitudinal survey study was conducted among 600 Dutch university employees to test relations between intra‐individual changes in subjective general health, future time perspective (FTP), and generativity and development motives. In line with the two lifespan theories, two processes were found. First, consistent with the disengagement perspective on aging, losses in subjective general health negatively predicted open‐ended FTP, and open‐ended FTP was positively associated with an increase in growth motives. Secondly, consistent with the activity perspective on aging, losses in subjective general health positively predicted limited FTP, and limited FTP was positively associated with an increase in generativity motives. In addition, initial open‐ended FTP predicted future open‐ended FTP through a change in subjective general health. Finally, these relations were found to differ across age groups, and thus over the lifespan. More specifically, losses in subjective general health and increases in limited FTP particularly result in lower development motives and higher generativity motives among middle‐aged workers, indicating that interventions aimed at preventing losses in health are probably most effective for maintaining development motives in this group.     

Physical activity,screen time and subjective well-being among children

Background/ObjectiveThe aim of the study was to explore the differences between physical activity and/or screen time levels on cognitive (Life satisfaction LS) and affective (Positive affect, PA and Negative affect NA) components of subjective well-being (SWB) in children.MethodThis cross-sectional study enrolled 1,540 children (1,040 boys, 8–12 years old). LS, PA, NA, physical activity and screen time were assessed with validated questionnaires.ResultsChildren who reported 3 days per week of physical activity or less had lower LS and PA than counterparts with ≥6 days of physical activity per week (p < .05). Participants who reported 2 hours per day or less of screen time had lower NA than counterparts with 4 hours per day or more of screen time (p < .05). Also, children who meet physical activity guidelines have higher LS and PA compared to inactive peers, even with high screen time. In contrast, excessive screen time was also related with NA independent of the level of physical activity.ConclusionsOur findings suggest that physical activity is related with positive feelings and LS, but does not eliminate the effect of screen time on negative feelings among Chilean children.     

A model of the influence of processing effort and number of changes on subjective time perception

The paper is concerned with a model for subjective time estimation as determined by processing effort and number of changes. In a previous paper, a proposal was made that should solve a problem of confounded variables in the area of time estimation. An experimental design was developed to allow for the independent manipulation of processing effort and number of changes. It is shown that this proposal is valid only under the assumption that Stevens' law holds with exponent one. Therefore, another way of conceptualizing this problem is advanced in which one asks for the relative impact of processing effort and change on the parameters of Stevens' law. It can be demonstrated that this law yields considerable fit despite interindividual differences.     

Attention and the subjective expansion of time

During brief, dangerous events, such as car accidents and robberies, many people report that events seem to pass in slow motion, as if time had slowed down. We have measured a similar, although less dramatic, effect in response to unexpected, nonthreatening events. We attribute the subjective expansion of time to the engagement of attention and its influence on the amount of perceptual information processed. We term the effect time's subjective expansion (TSE) and examine here the objective temporal dynamics of these distortions. When a series of stimuli are shown in succession, the low-probability oddball stimulus in the series tends to last subjectively longer than the high-probability stimulus even when they last the same objective duration. In particular, (1) there is a latency of at least 120 msec between stimulus onset and the onset of TSE, which may be preceded by subjective temporal contraction; (2) there is a peak in TSE at which subjective time is particularly distorted at a latency of 225 msec after stimulus onset; and (3) the temporal dynamics of TSE are approximately the same in the visual and the auditory domains. Two control experiments (in which the methods of magnitude estimation and stimulus reproduction were used) replicated the temporal dynamics of TSE revealed by the method of constant stimuli, although the initial peak was not apparent with these methods. In addition, a third, control experiment (in which the method of single stimuli was used) showed that TSE in the visual domain can occur because of semantic novelty, rather than image novelty per se. Overall, the results support the view that attentional orienting underlies distortions in perceived duration.     

Consistency of seizure frequency estimates across time, methods, and observers

Assessed the consistency of seizure frequency reports across observers, time, and methods. Thirty-two persons with intractable, partial seizures and 17 observers participated in a two-phase assessment procedure. During the first phase, subjects and observers provided retrospective seizure frequency estimates for two consecutive 30-day intervals. During the second phase, subjects and observers completed a daily seizure diary for 30 days. Patients' and observers' retrospective estimates were highly stable over a 2-month period. Substantial consistency was also found between two different recording methods (recall vs. diary) for subjects with epilepsy. In contrast, the observers' retrospective estimates were only moderately correlated with their prospective diary counts. Agreement between subjects' and observers' retrospective reports was also high. However, no significant association was found between their diary counts. Contrary to expectation, seizure frequency reports of patients with partial epilepsy showed moderately high consistency across time and between patient and observer pairs.     

The effects of averaging subjective probability estimates between and within judges

The average probability estimate of J > 1 judges is generally better than its components. Two studies test 3 predictions regarding averaging that follow from theorems based on a cognitive model of the judges and idealizations of the judgment situation. Prediction 1 is that the average of conditionally pairwise independent estimates will be highly diagnostic, and Prediction 2 is that the average of dependent estimates (differing only by independent error terms) may be well calibrated. Prediction 3 contrasts between- and within-subject averaging. Results demonstrate the predictions' robustness by showing the extent to which they hold as the information conditions depart from the ideal and as J increases. Practical consequences are that (a) substantial improvement can be obtained with as few as 2-6 judges and (b) the decision maker can estimate the nature of the expected improvement by considering the information conditions.     

An evaluation of speed management measures in Bangladesh based upon alternative accident recording,speed measurements,and DOCTOR traffic conflict observations

With 21,000 people annually killed in road traffic (estimated figure by World Health Organization), Bangladesh has one of the highest fatality rates in the world. Vulnerable road users (VRUs) account for over 50% of road traffic casualties, and 70% of casualties occur in rural areas. As in many Low and Middle Income Countries (LMICs), the official road accident statistics are incomplete and biased.Safe Crossings (Netherlands) and the Centre for Injury Prevention and Research Bangladesh (CIPRB) (Bangladesh) received permission from the Bangladesh government in 2014 to design and implement an integrated speed management program (consisting of a combination of small-scale infrastructural measures, active community involvement and road user education) at three locations where a national highway intersects small communities. The infrastructural countermeasures to improve road safety consisted of speed humps, rumble strips, signs and road markings and were designed following the Dutch road design guidelines. In a Before–After study design, we used a combination of three research methods to monitor and evaluate the road safety interventions. We created our own traffic accident recording system with trained local record keepers, we conducted laser-gun speed measurements of motorized traffic (both at intervention and control locations), and we applied the Dutch Objective Conflict Technique for Operation and Research (DOCTOR) for observing serious traffic conflicts at the intervention locations. The latter was based upon DOCTOR scores from video recordings of the behaviour at the three experimental locations Before and After the interventions.Prior to installing the intervention program, the three locations combined had, on average, about 100 serious accidents, 10 deaths, and 200 injured people on a yearly basis. In April 2015, all infrastructural measures were completed. In the after period (till the end of January 2016), the alternative accident recording system showed a 66% reduction in the number of serious accidents, a 73% reduction in the number of injured people, and a 67% reduction in the number of people killed.The unobtrusive laser-gun speed measurements resulted in a net reduction of 13.3 km/h (or 20% in relative terms) on average at the intervention locations by taking the general speed development at the control locations into account. According to Nilsson’s power law this would result in a 59% reduction of the number of people killed, well in line with the actual accident figures.The total number of serious conflicts (only DOCTOR scores 3, 4, and 5) was significantly reduced from 64 serious conflicts per location in a 4.5 h period Before to 29 serious conflicts in the After period, on average (Poisson distributed variable, p < 0.01), or a 55% reduction in relative terms. By including the traffic volumes, the reduction in conflict risk overall is 54%. Moreover, the severity of conflicts was reduced in the After period with only one most severe conflict (DOCTOR score 5) left. Buses represent the largest portion of road users involved in serious conflicts at all three locations, followed by cars and CNGs (Compressed Natural Gas vehicle). By far, the most frequently occurring conflict is of the type head-on conflict between an overtaking bus or car that is encountering a road user in opposite direction (for the greater part a CNG).All three evaluation measures point to a similar impact of the intervention program and unveil an improvement in road safety between 54% and 60%. The speed-reducing measures indeed considerably reduce the speed of motorized traffic, both the mean speed and 85th percentile values, both the number and severity of serious conflicts are reduced, and the actual number of accidents has decreased. It appears that Nilsson’s power law for the relation between a difference in mean speed and the change in the number of accidents also applies to LMICs.Speed management measures as common in high-income countries appear to be also effective in LMICs. For evaluation purposes of road safety impacts, a Traffic Conflicts Technique approach (also developed in high-income countries) seems valid and effective as well for application in LMICs.As there are thousands of traffic black spots with similar characteristics as the three intervention locations in Bangladesh, this integrated approach may well offer similar road safety improvements elsewhere.     

Aging and the speed of time

Correlational and experimental methods provide evidence relevant to seven theories of humans’ general impressions of the speed of time, including theories of the purported subjective acceleration of time with aging. A total of 1865 adults from two countries, ranging in age from 16 to 80, reported how fast time appears to pass over different spans of time. Other measures tapped the experience of life changes and time pressure, and experimental manipulations were used to test two models based on forward telescoping and difficulty of recall. Respondents of all ages reported that time seems to pass quickly. In contrast to widely held beliefs, age differences in reports of the subjective speed of time were very small, except for the question about how fast the last 10 years had passed. Findings support a theory based on the experience of time pressure.