The Effects of Subthreshold Autistic Traits On Time Perception: The Regulation of Interpersonal Information Association

Background People with high subthreshold autistic traits usually show structural impairments like those with autism spectrum disorder, but with less social and cognitive impairments. The effect of autistic traits on time perception and the role of interpersonal information on this effect remains unexplored. Methods This study used a temporal bisection task between 400–1600 ms to compare the time perception of individuals with higher and lower autistic traits, and to explore the influence of interpersonal information on their time perception by establishing associations between interpersonal information and geometric figures. A total of 32 participants with high autistic traits and 31 participants with low autistic traits took part in the study. Results In the absence of identity information, people with high autistic traits tended to judge short durations as longer, and their Weber ratio was higher than those with low autistic traits, suggesting that their overestimation of short duration is due to decreased temporal sensitivity and increased internal clock frequency. With the addition of interpersonal information, individuals with high and low autistic traits had faster responses to self in the identity-figure association, and the subjective bisection point was shorter. However, it took longer for individuals with high autistic traits to build the self-association, and there was no difference in the proportion of long response and Weber ratio between individuals with high and low autistic traits when identity was involved. Conclusion These results suggest that individuals with high autistic traits have a higher central tendency, and this change is related to the decline of perceptual sensitivity. Actively guiding attention to interpersonal information can improve the time perception sensitivity of individuals with high autistic traits.

Temporal bisection is influenced by ensemble statistics of the stimulus set

Although humans are well capable of precise time measurement, their duration judgments are nevertheless susceptible to temporal context. Previous research on temporal bisection has shown that duration comparisons are influenced by both stimulus spacing and ensemble statistics. However, theories proposed to account for bisection performance lack a plausible justification of how the effects of stimulus spacing and ensemble statistics are actually combined in temporal judgments. To explain the various contextual effects in temporal bisection, we develop a unified ensemble-distribution account (EDA), which assumes that the mean and variance of the duration set serve as a reference, rather than the short and long standards, in duration comparison. To validate this account, we conducted three experiments that varied the stimulus spacing (Experiment 1), the frequency of the probed durations (Experiment 2), and the variability of the probed durations (Experiment 3). The results revealed significant shifts of the bisection point in Experiments 1 and 2, and a change of the sensitivity of temporal judgments in Experiment 3—which were all well predicted by EDA. In fact, comparison of EDA to the extant prior accounts showed that using ensemble statistics can parsimoniously explain various stimulus set-related factors (e.g., spacing, frequency, variance) that influence temporal judgments.

Dissociable Effects of Emotional Stimuli on Perception and Decision-Making for Time

Previous research has demonstrated that negative emotional faces dilate time perception, however, the mechanisms underlying this phenomenon are not fully understood. Previous attempts focus on the pacemaker-accumulator model of time perception, which includes a clock, memory, and decision-making stage, wherein emotion affects one of these stages; possibly by increasing pacemaker rate via arousal, increasing accumulation rate via attention, or by biasing decision-making. To further investigate the stage(s) that emotion is affecting time perception we conducted a visual temporal bisection task with sub-second intervals while recording 64-channel electroencephalogram (EEG). To separate the influence of face and timing responses the temporal stimulus was preceded and followed by a face stimulus displaying a neutral or negative expression creating three trial-types: Neg→Neut, Neut→Neg, or Neut→Neut. The data revealed a leftward shift in bisection point (BP) in Neg→Neut and Neut→Neg suggesting an overestimation of time. Neurally, we found the face-responsive N170 component was larger for negative faces and the N1 and contingent negative variation (CNV) were larger when preceded by a negative face. We also found an interaction effect between condition and response for the late positive component of timing (LPCt) and a significant difference between response (short/long) in the neutral condition. We conclude that a preceding negative face affects the clock stage leading to more pulses being accumulated, either through attention or arousal, as indexed by a larger N1, CNV, and N170; whereas viewing the negative face second biased decision-making leading to “short” responses being less likely, as evidenced by the LPCt.

Executive processes and timing: Comparing timing with and without reference memory

Temporal perception is influenced by executive function. However, performance on different temporal tasks is often associated with different executive functions. This study examined whether using reference memory during a task influenced how performance was associated with executive resources. Participants completed temporal generalisation and bisection tasks, in their normal versions involving reference memory and in episodic versions without reference memory. Each timing task had two difficulty levels: easy and hard. Correlations between performance on these tasks and measures of executive function (updating, inhibition, task switching, and access to semantic memory) were assessed. Accuracy on the temporal generalisation task was correlated with memory access for all versions of the task. Updating correlated with accuracy only for the reference memory-based version of the task. Temporal bisection performance presented a different pattern of correlations. The bisection point was negatively correlated with inhibition scores, except for the easy episodic condition. The Weber ratio, considered a measure of temporal sensitivity, was negatively correlated with memory access only in the hard episodic condition. Together, the findings suggest that previous models of generalisation and bisection may not accurately reflect the underlying cognitive processes involved in the tasks.

Controlling for temporal discounting shifts rats from geometric to human-like arithmetic bisection

How our brains measure the passage of time is still largely open for debate. One behavioral task commonly used to study how durations are perceived is the Temporal Bisection Task, in which subjects categorize time durations as either “short” or “long.” The duration equally likely to be categorized as short or long is known as the bisection point. It has been consistently demonstrated that for humans, the bisection point is near the arithmetic mean of the longest and shortest durations the subject was trained on. In contrast, for non-human subjects it has been consistently found near the geometric mean. This difference implies that humans may process or represent temporal durations differently than other species. Here we present a behavioral model that reconciles the differences by demonstrating that rats’ performance on this task is driven not only by their noisy estimates of duration, but also by the temporally-discounted value of future rewards. The model correctly predicts shifts in the bisection point induced by unequal rewards and explains otherwise-paradoxical psychometric reversals documented three decades ago. Furthermore, as predicted by the model, we found that modifying the Temporal Bisection Task to eliminate the temporally-discounted reward component shifted the rats’ bisection point from the geometric mean to the arithmetic mean, thus bringing the rat results into line with the human results. We therefore propose that humans and rats (and perhaps other non-human subjects as well) process temporal information similarly, and that the difference between them in the Temporal Bisection Task may be simply due to rats weighing temporal discounting of future rewards more strongly than humans.

Assessment of intertemporal preferences in type-2 diabetes patients and smokers

The experiment assesses the role of cortisol concentration on bloodstream as correlate of the intertemporal choice and temporal discrimination in Type-2 Diabetes Mellitus (T2DM) patients and smokers. The participants were evaluated in a two independent computerized tasks allowed to obtain the temporal discount function and it’s hyperbolic decay parameter (k), which refers to the tendency to discount the subjective value of future goods as a function of the delay to receiving them; and a temporal discrimination index (bisection point), this function relate the response proportion of “Long” stimuli with probe duration. The bisection point is the value at which responses to Short and Long stimuli occur with equal frequency. We analysed both parameters, then a comparisons of the temporal discount parameter[F(2,147) =79.858,p<,01]and time discrimination parameter[F(2,147) =49,51,p<,01]revealed statistically significant differences between control group and T2DM and smokers groups. We concluded that the choice for delayed rewards and the temporal discrimination of T2DM patients and smokers were influenced by the cortisol concentration in the bloodstream; the higher the concentration of cortisol in the bloodstream, the higherthe likelihood to choose immediate rewards over larger delayed rewards and the higher the tendency tooverestimate the passage of time. We propose to investigate the effects of salivary cortisol elevation levels through noninvasive pharmacologically induction on healthy adult humans, to extend the research line that assess the direct influence over intertemporal choice and temporal discrimination to increase the effect generality.

Emotion and Time Perception in Children and Adults: The Effect of Task Difficulty

In the present study, adults and children aged five and eight years were given a temporal bisection task involving emotional stimuli (angry and neutral faces) and three levels of discrimination difficulty that differed as a function of the ratio used between the short and the long standard duration (very easy, easy, and difficult). In addition, their cognitive capacities in terms of working memory and attention inhibition were assessed by neuropsychological tests. In the very easy temporal task (ratio of 1:4), the results showed that the psychophysical functions were shifted toward the left in all participants for the angry faces compared to the neutral faces, with a significant lowering of the Bisection Point, suggesting that the stimulus duration was judged to last longer for the emotional stimuli. In addition, the results did not show any relationship between the magnitude of this lengthening effect and individual cognitive capacities as assessed by the neuropsychological tests. The individual differences in working memory capacities only explained differences in sensitivity to time. However, when the difficulty of the temporal task increased, the children’s performance decreased and it was no longer possible to test for the emotional effect. Unlike the children, the adults were still able to discriminate time in the emotional task. However, the emotional effect was no longer observed. In conclusion, our study on temporal task difficulty shows the influence of available cognitive resources on the emergence of an emotional effect on time perception.

Speeding up an Internal Clock in Children? Effects of Visual Flicker on Subjective Duration

Children of 3, 5, and 8 years of age were trained on a temporal bisection task where visual stimuli in the form of blue circles of 200 and 800 ms or 400 and 1600 ms duration, preceded by a 5-s white circle, served as the short and long standards. Following discrimination training between the standards, stimuli in the ranges 200-800 ms or 400-1600 ms were presented with the white circle either constant or flickering. Relative to the constant white circle, the flicker (1) increased the proportion of “long” responses (responses appropriate to the long standard), (2) shifted the psychophysical functions to the left, (3) decreased bisection point values, at all ages, and (4) did not systematically affect measures of temporal sensitivity, such as difference limen and Weber ratio. The results were consistent with the idea that the repetitive flicker had increased the speed of the pacemaker of an internal clock in children as young as 3 years. The “pacemaker speed” interpretation of the results was further strengthened by a greater effect of flicker in the 400/1600-ms condition than in the 200/800-ms condition.