Time interaction with two spatial dimensions: from left/right to near/far

We explore time and space relationship according to two spatial coding: the left/right extension and the reachability of stimulus along a near/far dimension. Four experiments were carried out in which healthy participants performed the Time and Spatial Bisection tasks in near/far space, before and after a short or long tool-use training. Stimuli were prebisected horizontal lines of different temporal durations in which the midpoint was manipulated according to Muller-Lyer illusion. The perceptual illusory effects emerged in spatial but not temporal judgments. We revealed that temporal and spatial representations dynamically change accordingly with individual’s action potentialities: temporal duration was perceived as shorter and the perceived line’s midpoint was shifted to the left in far than in near space. Crucially, this dissociation disappeared following a long but not short tool-use training. Finally, we observed age-related difference in spatial attention which may be crucial in built the memory temporal standard to categorize durations.

The precision of retrieving temporal information : behavioral and electrophysiological studies

The knowledge of when an event took place provides benefits to episodic memory, such as distinguishing among multiple traces and learning event sequences. As a tool for understanding memory, time is appealing given its ever-changing quality, and the ease with which it is targeted at retrieval. Whereas studies of episodic retrieval typically employ categorical measures of retrieval, characterizing a continuous feature such as time warrants measures sensitive to the precision of retrieved information. Through four experiments, we adapted a paradigm for assessing the fine-grained precision of retrieval to understand the nature of judging the time at which a memory was encoded. Subjects studied a series of pictures and were subsequently tested on when they previously studied items. Temporal judgments were less accurate with passing time, with negligible guessing. Neurally, ERP amplitudes in left parietal electrodes tracked the precision of temporal judgments, with higher ERP amplitudes associated with better precision. Additionally, frequency power in both the alpha and theta bands were associated with temporal precision. Finally, while testing spatial retrieval, a correspondence emerged between spatial and temporal precision on a trial to trial basis, but a dissociation was found in which the recency effects found in temporal judgments was not present in spatial judgments. Together, these findings elucidate the role of time and space in episodic memory retrieval.

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.

Common and distinct roles of frontal midline theta and occipital alpha oscillations in coding temporal intervals and spatial distances

Judging how far something is and how long it takes to get there are critical to memory and navigation. Yet, the neural codes for spatial and temporal information remain unclear, particularly how and whether neural oscillations might be important for such codes. To address these issues, participants traveled through teleporters in a virtual town while we simultaneously recorded scalp EEG. Participants judged the distance and time spent inside the teleporter. Our findings suggest that alpha power relates to distance judgments while frontal theta power relates to temporal judgments. In contrast, changes in alpha frequency and beta power indexed both spatial and temporal judgments. We also found evidence for fine-grained temporal coding and an effect of past trials on temporal but not spatial judgments. Together, these findings support partially independent coding schemes for spatial and temporal information, and suggest that low-frequency oscillations play important roles in coding both space and time.

The Diminishing Precision of Memory for Time

Knowing when an event took place can provide several benefits to episodic memory, such as distinguishing among multiple traces, learning sequences of events, and guiding a search strategy. As a tool for understanding memory, time is particularly appealing given its ever-changing quality, the constant possibility to associate it with encoded events, and the ease with which it can be targeted at retrieval. Whereas studies of episodic retrieval typically employ categorical and probabilistic measures of retrieval success, characterizing a continuous feature such as time warrants measures particularly sensitive to the fidelity, or precision, of retrieved information. Here, we adapt a paradigm for assessing the fine-grained precision of retrieval to understand the nature of judging the time at which a memory was encoded. Subjects studied a series of pictures and then undertook a test in which they placed each picture, as precisely as possible, along a continuous timeline representing the study list. Based on mixture-modeling analyses of the test response errors, the primary results were that temporal judgments were less accurate with passing time, and this change was due to diminished precision as opposed to an increased rate of guessing. Moreover, although we observed a negligible influence of guessing, subjects exhibited a clear effect of bias that favored recent responses. Together, in contrast to numerous studies of memory for other continuous features (e.g., color and location), our findings demonstrate a novel pattern of decision factors, suggesting that the retrieval of time might highlight distinct attributes of episodic memory.

Alpha/beta power compresses time in sub-second temporal judgments

ABSTRACTWhile the perception of time plays a crucial role in our day-to-day functioning, the underlying neural mechanism of time processing on short time scales (~1s) remains to be elucidated. Recently, the power of beta oscillations (~20 Hz) has been suggested to play an important role in temporal processing. However, the paradigms supporting this view have often had confounds of working memory, as well as motor preparation. In the current EEG study, we set out to investigate if power of oscillatory activity would be involved in time perception without an explicit working memory component or confound of a motor response. Participants indicated through a button press whether the time between a tone and a visual stimulus was 1 or 1.5s.Critically, we focused on the differences in oscillatory activity in the alpha (~10 Hz) and beta (~20 Hz) ranges preceding correct versus incorrect temporal judgments. Behaviourally, we found participants made more errors on the long (1.5s) than on the short (1s) interval. In addition, we found that participants were fastest to correctly respond to a long interval. The onset of the tone induced a suppression of alpha and beta activity over occipital and parietal electrodes. In the long estimation intervals, this suppression was greater for correct than incorrect estimations. Interestingly, alpha and beta suppression allowed us to predict whether participants would judge the long interval correctly. For the short interval trials we did not find a significant difference in alpha or beta band activity for the correct and incorrect judgments. Taken together, our behavioural and EEG results suggest a multifaceted role of alpha and beta activity in the temporal estimation of sub- and supra-second intervals, where power increases seem to lead to temporal compression. Higher alpha and beta power resulted in shorter temporal judgments for sub-second intervals.HighlightsTemporal judgments without motor confounds were studied with EEG.Alpha/beta activity differences for correct and incorrect temporal judgments.Sub-second intervals were judged as short when alpha/beta power was higher.