Sub- and Supra-Second Timing in Auditory Perception: Evidence for Cross-Domain Relationships

Previous studies indicate that there are at least two levels of temporal processing: the sub- and supra-second domains. The relationship between these domains remains unclear. The aim of this study was to test whether performance on the sub-second level is related to that on the supra-second one, or whether these two domains operate independently. Participants were 118 healthy adults (mean age = 23 years). The sub-second level was studied with a temporal-order judgment task and indexed by the Temporal Order Threshold (TOT), on which lower values corresponded to better performance. On the basis of TOT results, the initial sample was classified into two groups characterized by either higher temporal efficiency (HTE) or lower temporal efficiency (LTE). Next, the efficiency of performance on the supra-second level was studied in these two groups using the subjective accentuation task, in which participants listened to monotonous sequences of beats and were asked to mentally accentuate every n-th beat to create individual rhythmic patterns. The extent of temporal integration was assessed on the basis of the number of beats being united and better performance corresponded to longer units. The novel results are differences between groups in this temporal integration. The HTE group integrated beats in significantly longer units than did the LTE group. Moreover, for tasks with higher mental load, the HTE group relied more on a constant time strategy, whereas the LTE group relied more on mental counting, probably because of less efficient temporal integration. These findings provide insight into associations between sub- and supra-second levels of processing and point to a common time keeping system, which is active independently of temporal domain.

Perceived Timing of Cutaneous Vibration and Intracortical Microstimulation of Human Somatosensory Cortex

BackgroundElectrically stimulating the somatosensory cortex can partially restore the sense of touch. Though this technique bypasses much of the neuroaxis, prior studies with non-human primates have found that conscious detection of touch elicited by intracortical microstimulation (ICMS) lags behind the detection of vibration applied to the skin. These findings may have been influenced by a mismatch in stimulus intensity; typically, vibration is perceived as more intense than ICMS, which can significantly impact temporal perception.ObjectiveThe goal of this study was to evaluate the relative latency at which intensity-matched vibration and ICMS are perceived in a human subject.MethodsA human participant implanted with microelectrode arrays in somatosensory cortex performed a reaction time task and a temporal order judgment (TOJ) task. In the reaction time task, the participant was presented with ICMS or vibration and verbal response times were obtained. In the TOJ task, the participant was sequentially presented with a pair of stimuli – ICMS followed by vibration or vice versa – and reported which stimulus occurred first.ResultsWhen ICMS and vibration were matched in perceived intensity, the reaction time to vibration was ∼50 ms faster than ICMS. However, in the TOJ task, ICMS and vibratory sensations arose at comparable latencies, with points of subjective simultaneity that were not significantly different from zero.ConclusionsBecause the perception of ICMS is slower than that of intensity-matched vibration, it may be necessary to stimulate at stronger ICMS intensities (thus decreasing reaction time) when incorporating ICMS sensory feedback into neural prostheses.

Visual field differences in temporal synchrony processing for audio-visual stimuli

Audio-visual integration relies on temporal synchrony between visual and auditory inputs. However, differences in traveling and transmitting speeds between visual and auditory stimuli exist; therefore, audio-visual synchrony perception exhibits flexible functions. The processing speed of visual stimuli affects the perception of audio-visual synchrony. The present study examined the effects of visual fields, in which visual stimuli are presented, for the processing of audio-visual temporal synchrony. The point of subjective simultaneity, the temporal binding window, and the rapid recalibration effect were measured using temporal order judgment, simultaneity judgment, and stream/bounce perception, because different mechanisms of temporal processing have been suggested among these three paradigms. The results indicate that auditory stimuli should be presented earlier for visual stimuli in the central visual field than in the peripheral visual field condition in order to perceive subjective simultaneity in the temporal order judgment task conducted in this study. Meanwhile, the subjective simultaneity bandwidth was broader in the central visual field than in the peripheral visual field during the simultaneity judgment task. In the stream/bounce perception task, neither the point of subjective simultaneity nor the temporal binding window differed between the two types of visual fields. Moreover, rapid recalibration occurred in both visual fields during the simultaneity judgment tasks. However, during the temporal order judgment task and stream/bounce perception, rapid recalibration occurred only in the central visual field. These results suggest that differences in visual processing speed based on the visual field modulate the temporal processing of audio-visual stimuli. Furthermore, these three tasks, temporal order judgment, simultaneity judgment, and stream/bounce perception, each have distinct functional characteristics for audio-visual synchrony perception. Future studies are necessary to confirm the effects of compensation regarding differences in the temporal resolution of the visual field in later cortical visual pathways on visual field differences in audio-visual temporal synchrony.

Time changes: Timing contexts support event segmentation in associative memory

We tend to mentally segment a series of events according to perceptual contextual changes, such that items from a shared context are more strongly associated in memory than items from different contexts. It is also known that timing context provides a scaffold to structure experiences in memory, but its role in event segmentation has not been investigated. We adapted a previous paradigm, which was used to investigate event segmentation using visual contexts, to study the effects of changes in timing contexts on event segmentation in associative memory. In two experiments, we presented lists of 36 items in which the interstimulus intervals (ISIs) changed after a series of six items ranging between 0.5 and 4 s in 0.5 s steps. After each list, participants judged which one of two test items were shown first (temporal order judgment) for items that were either drawn from the same context (within an ISI) or from consecutive contexts (across ISIs). Further, participants judged from memory whether the ISI associated to an item lasted longer than a standard interval (2.25 s) that was not previously shown (temporal source memory). Experiment 2 further included a time-item encoding task. Results revealed an effect of timing context changes in temporal order judgments, with faster responses (Experiment 1) or higher accuracy (Experiment 2) when items were drawn from the same context, as opposed to items drawn from across contexts. Further, in both experiments, we found that participants were well able to provide temporal source memory judgments based on recalled durations. Finally, replicated across experiments, we found subjective duration bias, as estimated by psychometric curve fitting parameters of the recalled durations, correlated negatively with within-context temporal order judgments. These findings show that changes in timing context support event segmentation in associative memory.

Evidence for a general impairment of auditory and visual temporal order judgment in children with reading disabilities

Objectives: This study examined visual and auditory processing of children with reading disabilities (RD) to determine whether they show an impaired ability to judge a reading-related process such as temporal order of events and clarify whether or not this deficit is linked to rapid processing deficit. Method: The performance of 16 children with RD was compared with the performance of children in two control groups – one for chronological age (CA) and one for the same reading level –, doing visual and auditory temporal order tasks, both with linguistic and non-linguistic stimuli with inter-stimuli-intervals of 50, 150, or 300 ms. Results: The RD group performance was lower than the performance of the CA group in tasks requiring auditory temporal order processing for linguistic and non-linguistic stimuli. Regarding visual tasks, the RD group performed worse than both control groups in processing non-linguistic stimuli. In general, performance in every group decreased with decreasing inter-stimulus-interval (ISIs), suggesting that children with RD do not have impairments in the speed of perceptual processing. Conclusions: The perceptual problems of children with RD are better explained by temporal order processing problems than by difficulties in rapid processing. Inclusion of temporal order processing tasks in the evaluation of children with RD is recommended.

Broad scope of attention results in better temporal resolution: Evidence from a temporal order judgment study

The nature of spatiotemporal interactions in visual perception due to modulations of attention is still not well understood. Transient shifts of attention have been shown to induce a trade-off in spatiotemporal acuities at the cued location. Attention also can be varied in terms of scope and the evidence for the effects of scope on the spatiotemporal resolution for coupling or trade-offs have been equivocal. We predicted that scaling or changing the scope of attention would rather result in a spatiotemporal trade-off based on the complementary spatial and temporal frequency properties of the magnocellular and parvocellular channels. We manipulated the scope of attention by asking participants to perform a global or local target detection task with hierarchical stimuli. In addition, participants performed a temporal order judgment task with two discs presented alongside the hierarchical stimuli. We found higher temporal sensitivity with broad scope of attention or global processing compared to narrow scope of attention or local processing. The results provide evidence for a spatiotemporal processing trade-off when attention is scaled spatially. This result throws doubt on a general coupling or resource metaphor explanation irrespective of the spatial or temporal nature of the tasks. The results indicate the further need for carefully investigating the spatial and temporal properties of attention and its effect on spatiotemporal processing at different scales.

Early Capture of Attention by Self-Face: Investigation Using a Temporal Order Judgment Task

Earlier work on self-face processing has reported a bias in the processing of self-face result in faster response to self-face in comparison to other familiar and unfamiliar faces (termed as self-face advantage or SFA). Even though most studies agree that the SFA occurs due to an attentional bias, there is little agreement regarding the stage at which it occurs. While a large number of studies show self-face influencing processing later at disengagement stage, early event-related potential components show differential activity for the self-face suggesting that SFA occurs early. We address this contradiction using a cueless temporal order judgment task that allows us to investigate early perceptual processing, while bias due to top-down expectation is controlled. A greater shift in point of subjective simultaneity for self-face would indicate a greater processing advantage at early perceptual stage. With help of two experiments, we show an early perceptual advantage for self-face, compared to both a friend’s face and an unfamiliar face (Experiment 1). This advantage is present even when the effect of criterion shift is minimized (Experiment 2). Interestingly, the magnitude of advantage is similar for self-friend and self-unfamiliar pair. The evidence from the two experiments suggests early capture of attention as a likely reason for the SFA, which is present for the self-face but not for other familiar faces.

Tapping Force Encodes Metrical Aspects of Rhythm

Humans possess the ability to extract highly organized perceptual structures from sequences of temporal stimuli. For instance, we can organize specific rhythmical patterns into hierarchical, or metrical, systems. Despite the evidence of a fundamental influence of the motor system in achieving this skill, few studies have attempted to investigate the organization of our motor representation of rhythm. To this aim, we studied—in musicians and non-musicians—the ability to perceive and reproduce different rhythms. In a first experiment participants performed a temporal order-judgment task, for rhythmical sequences presented via auditory or tactile modality. In a second experiment, they were asked to reproduce the same rhythmic sequences, while their tapping force and timing were recorded. We demonstrate that tapping force encodes the metrical aspect of the rhythm, and the strength of the coding correlates with the individual’s perceptual accuracy. We suggest that the similarity between perception and tapping-force organization indicates a common representation of rhythm, shared between the perceptual and motor systems.