Evidence for different processes involved in the effects of nontemporal stimulus size and numerical digit value on duration judgments

Error modulates categorization of subsecond durations in multitasking contexts

Monitoring errors consumes limited cognitive resources and can disrupt subsequent task performance in multitasking scenarios. However, there is a dearth of empirical evidence concerning this interference with prospective estimation of time. In this study, we sought to investigate this issue through a serial multitasking experiment, employing a temporal bisection task as the primary task. We introduced two task contexts by implementing two different concurrent tasks. In one context, participants were tasked with discriminating the size difference between two visual items, while in the other context, they were required to judge the temporal order of similar visual items. The primary task remained the same for the entire experiment. Psychophysical metrics, including subjective bias (determined by the bisection point) and temporal sensitivity (measured by the Weber ratio), in addition to reaction time, remained unaltered in the primary task regardless of the perceptual context exerted by the concurrent tasks. However, commission of error in the concurrent tasks (i.e., non-specific errors) led to a right-ward shift in the bisection point, indicating underestimation of time after errors. Applying a drift-diffusion framework for temporal decision making, we observed alterations in the starting point and drift rate parameters, supporting the error-induced underestimation of time. The error-induced effects were all diminished with increasing a delay between the primary and concurrent task, indicating an adaptive response to errors at a trial level. Furthermore, the error-induced shift in the bisection point was diminished in the second half of the experiment, probably because of a decline in error significance and subsequent monitoring response. These findings indicate that non-specific errors impact the prospective estimation of time in multitasking scenarios, yet their effects can be alleviated through both local and global reallocation of cognitive resources from error processing to time processing.

Time and visual-spatial illusions: Evidence for cross-dimensional interference between duration and illusory size

Time and space are intimately related to each other. Previous evidence has shown that stimulus size can affect perceived duration even when size differences are illusory. In the present study, we investigated the effect of visual-spatial illusions on duration judgments in a temporal reproduction paradigm. Specifically, we induced the Ebbinghaus illusion (Exp. 1) and the horizontal-vertical illusion (Exp. 2) during the encoding phase of the target interval or the reproduction phase. The results showed (a) that illusory size affects temporal processing similarly to the way physical size does, (b) that the effect is independent of whether the illusion appeared during encoding or reproduction, and (c) that the interference between size and temporal processing is bidirectional. These results suggest a rather late locus of size-time interference in the processing stream.

The effect of magnitude in a simultaneous duration assessment task among children - a replication study

The "magnitude effect" refers to the phenomenon where stimuli of greater magnitude appear to last longer in duration. Previous studies have explored this effect among children using various duration assessment tasks, but the findings have been inconsistent. Moreover, no replication studies have been conducted on this topic among children thus far. The simultaneous duration assessment task, which is one method for investigating time perception, has been used only twice in children and produced the magnitude effect. Thus, we aimed to replicate these findings and validate them through an additional replicated study. For these aims, we recruited 45 Arab-speaking children aged 7-12 to participate in two studies. In Study 1, they were asked to perform a simultaneous duration assessment task, where they had to assess the illumination durations of lightbulbs with strong and weak intensities simultaneously. In Study 2, they were asked to perform a duration reproduction task, where they had to reproduce the durations of illumination of the same stimuli. Both studies found a magnitude effect pattern, where the children tended to report that the lightbulb with the stronger intensity was illuminated for a longer duration or had a strong tendency to not choose the lightbulb with the weaker intensity. These results are discussed in terms of possible explanations for the conflicting results found in previous literature, as well as their consistency with the pacemaker model's explanation for the effect.

Decisional carryover effects in interval timing: Evidence of a generalized response bias

Decisional carryover refers to the tendency to report a current stimulus as being similar to a prior stimulus. In this article, we assess decisional carryover in the context of temporal judgments. Participants performed a temporal bisection task wherein a probe between a long and short reference duration (Experiment 1) was presented on every trial. In Experiment 2, every other trial presented a duration the same as the short or long reference duration. In Experiment 3, we concurrently varied both the size and duration of stimuli. Experiment 1 demonstrated the typical decisional carryover effect in which the current response was assimilated towards the prior response. In Experiment 2, this was not the case. Conversely, in Experiment 2, we demonstrated decisional carryover from the prior probe decision to the reference duration trials, a judgment which should have been relatively easy. In Experiment 3, we found carryover in the judgment of both size and duration, and a tendency towards decisional carryover having a larger effect size when participants were making size judgments. Together, our findings indicate that decisional carryover in duration judgments occur given relatively response-certain trials and that this effect appears to be similar in both size and duration judgments. This suggest that decisional carryover is indeed decisional in nature, rather than due to assimilative effects in perception, and that the difficulty of judging the previous test stimuli may play a role in whether assimilation occurs in the following trial when judging duration.

Local context effects in the magnitude-duration illusion: Size but not numerical value sequentially alters perceived duration

Many aspects of an event can change perceived duration. A common example of this is the magnitude-duration illusion, in which a high magnitude (e.g. large or high value) stimulus will be perceived to last longer than a low magnitude stimulus. The effects of magnitude on perceived duration are normally considered in terms of global context effects; what is large depends on the stimuli used throughout the experiment. In the current article, we examine local context effects in the magnitude-duration illusion, how trial-by-trial changes in magnitude affect the subjective duration of an event. We performed two experiments in which numerical magnitude and stimulus size were varied within either the example phase or reproduction phase of a temporal reproduction task. We showed that in the current trial the combined value-size magnitude presented in the example phase affected subsequent reproductions, while the magnitude presented in the reproduction phase did not. The size magnitude presented in the reproduction phase also affected the reproduction in the following trial, such that a larger stimulus in the current reproduction phase resulted in shorter reproductions in the next reproduction phase. This indicates that low level stimulus properties (i.e. size) can act to contextualize subsequent stimulus properties, which in turn affect perceived duration. The findings of our experiments add local, low-level, context effects to the known modifiers of perceived duration, as well as provide evidence with regards to the role of magnitude in interval timing.

Holistic representation of negative numbers: Evidence from duration comparison tasks

Whether negative numbers are represented componentially as two separate components (a digit and a sign) or represented holistically as a whole is still under debate. The present study investigated the representation of negative numbers via duration comparison tasks that might eliminate the possible influences of the strategies participants usually use when processing numbers. In the duration comparison task, participants are required to compare the durations of two numbers that were presented sequentially, thus the numerical value is irrelevant to the task. Our results showed that negative numbers were processed holistically when positive numbers and negative numbers were presented in separate blocks (Exp. 1). But negative numbers showed a componential representation when positive numbers were intermixed with negative numbers within the same block (Exp. 2). This inconsistency might be due to the spatial separation of the polarity sign and digit components in negative numbers which may remind participants that negative numbers are formed by two components when there are positive numbers as a comparison in the same block. Therefore, when the spatial separation of the polarity sign and digit components in negative numbers was eliminated by using colors to mark the polarity (Exp. 3), the negative numbers were processed holistically even when positive numbers and negative numbers were intermixed. These results suggest that negative numbers are represented holistically and may be prone to be represented componentially when intermixed with positive numbers within the same block.

Motion-induced compression of perceived numerosity

It has been recently proposed that space, time, and number might share a common representation in the brain. Evidence supporting this idea comes from adaptation studies demonstrating that prolonged exposure to a given stimulus feature distorts the perception of different characteristics. For example, visual motion adaptation affects both perceived position and duration of subsequent stimuli presented in the adapted location. Here, we tested whether motion adaptation also affects perceived numerosity, by testing the effect of adaptation to translating or rotating stimuli moving either at high (20 Hz) or low (5 Hz) speed. Adaptation to fast translational motion yielded a robust reduction in the apparent numerosity of the adapted stimulus (~25%) while adaptation to slow translational or circular motion (either 20 Hz or 5 Hz) yielded a weaker but still significant compression. Control experiments suggested that none of these results could be accounted for in terms of stimulus masking. Taken together, our results are consistent with the extant literature supporting the idea of a generalized magnitude system underlying the representation of numerosity, space and time via common metrics. However, as changes in perceived numerosity co-varied with both adapting motion profile and speed, our evidence also suggests complex and asymmetric interactions between different magnitude representations.

A Bayesian Perspective on Accumulation in the Magnitude System

Several theoretical and empirical work posit the existence of a common magnitude system in the brain. Such a proposal implies that manipulating stimuli in one magnitude dimension (e.g. duration in time) should interfere with the subjective estimation of another magnitude dimension (e.g. size in space). Here, we asked whether a generalized Bayesian magnitude estimation system would sample sensory evidence using a common, amodal prior. Two psychophysical experiments separately tested participants on their perception of duration, surface, and numerosity when the non-target magnitude dimensions and the rate of sensory evidence accumulation were manipulated. First, we found that duration estimation was resilient to changes in surface and numerosity, whereas lengthening (shortening) the duration yielded under- (over-) estimations of surface and numerosity. Second, the perception of surface and numerosity were affected by changes in the rate of sensory evidence accumulation, whereas duration was not. Our results suggest that a generalized magnitude system based on Bayesian computations would minimally necessitate multiple priors.