On the relationship between general fluid intelligence and psychophysical indicators of temporal resolution in the brain

Resting-state fMRI functional connectivity of the left temporal parietal junction is associated with visual temporal order threshold

The study aimed to determine the relationship between the millisecond timing, measured by visual temporal order threshold (TOT), i.e. a minimum gap between two successive stimuli necessary to judge a before-after relation, and resting-state fMRI functional connectivity (rsFC). We assume that the TOT reflects a relatively stable feature of local internal state networks and is associated with rsFC of the temporal parietal junction (TPJ). Sixty five healthy young adults underwent the visual TOT, fluid intelligence (G_f) and an eyes-open resting-state fMRI examination. After controlling for the influence of gender, the higher the TOT, the stronger was the left TPJ’s rsFC with the left postcentral and the right precentral gyri, bilateral putamen and the right supplementary motor area. When the effects of G_f and TOT × G_f interaction were additionally controlled, the TOT—left TPJ’s rsFC relationship survived for almost all above regions with the exception of the left and right putamen. This is the first study demonstrating that visual TOT is associated with rsFC between the areas involved both in sub-second timing and motor control. Current outcomes indicate that the local neural networks are prepared to process brief, rapidly presented, consecutive events, even in the absence of such stimulation.

The electrophysiological masking level difference: effects of age and mediation of hearing and cognition

OBJECTIVE

Evaluate the conceptual framework that age effects on the electrophysiological binaural masking level difference (MLD) are partially mediated by age-related hearing loss and/or global cognitive function via mediation analysis.

DESIGN

Participants underwent a series of audiometric tests. The MLD was measured via cortical auditory evoked potentials using a speech stimulus (/ɑ/) in speech-weighted background noise. We used mediation analyses to determine the total effect, natural direct effects, and natural indirect effects, which are displayed as regression coefficients ([95% CI]; p value).

STUDY SAMPLE

Twenty-eight individuals aged 19-87 years (mean [SD]: 53.3 [25.2]), recruited from the community.

RESULTS

Older age had a significant total effect on the MLD (-0.69 [95% CI: -0.96, -0.45]; p < 0.01). Neither pure tone average (-0.11 [95% CI: -0.43, 0.24; p = 0.54] nor global cognitive function (-0.02 [95% CI: -0.13, 0.02]; p = 0.55) mediated the relationship of age and the MLD and effect sizes were small. Results were insensitive to use of alternative hearing measures or inclusion of interaction terms.

CONCLUSIONS

The electrophysiological MLD may be an age-sensitive measure of binaural temporal processing that is minimally affected by age-related hearing loss and global cognitive function.

Identifying reliable change in tactile temporal thresholds in multiple sclerosis: test-retest reliability

Background Tactile temporal thresholds are typically significantly higher (ie, prolonged) in multiple sclerosis (MS) patients when compared to controls and increase significantly during relapses, probably reflecting integrity of conduction across a portion of the corpus callosum. As part of an ongoing validation study of tactile temporal thresholds, the test-retest reliability of these thresholds was examined in patients with MS.

Methods Tactile temporal thresholds were measured in 61 MS patients during two separate test sessions within three weeks. Test-retest reliability and the standard error of measurement were calculated. The threshold of change in tactile temporal thresholds in MS patients that would correspond to real change beyond measurement error with 95% certainty was also calculated.

Results The test-retest reliability of this measure of tactile temporal thresholds was 0.93. The threshold indicating change beyond chance or measurement error with 95% certainty was 19 ms.

Conclusions This measure of tactile temporal thresholds has excellent test - retest reliability and a change of greater than 19 ms is highly likely to represent real change. This measure is promising as a precise, reliable outcome measure in MS.

Analysis of Genetic and Non-Genetic Factors Influencing Timing and Time Perception

Performance on different psychophysical tasks measuring the sense of time indicates a large amount of individual variation in the accuracy and precision of timing in the hundredths of milliseconds-to-minutes range. Quantifying factors with an influence on timing is essential to isolating a biological (genetic) contribution to the perception and estimation of time. In the largest timing study to date, 647 participants completed a duration-discrimination task in the sub-second range and a time-production task in the supra-second range. We confirm the stability of a participant's time sense across multiple sessions and substantiate a modest sex difference on time production. Moreover, we demonstrate a strong correlation between performance on a standardized cognitive battery and performance in both duration-discrimination and time-production tasks; we further show that performance is uncorrelated with age after controlling for general intelligence. Additionally, we find an effect of ethnicity on time sense, with African Americans and possibly Hispanics in our cohort differing in accuracy and precision from other ethnic groups. Finally, a preliminary genome-wide association and exome chip study was performed on 148 of the participants, ruling out the possibility for a single common variant or groups of low-frequency coding variants within a single gene to explain more than ~18% of the variation in the sense of time.

In search of the internal structure of the processes underlying interval timing in the sub-second and the second range: a confirmatory factor analysis approach

One of the earliest accounts of duration perception by Karl von Vierordt implied a common process underlying the timing of intervals in the sub-second and the second range. To date, there are two major explanatory approaches for the timing of brief intervals: the Common Timing Hypothesis and the Distinct Timing Hypothesis. While the common timing hypothesis also proceeds from a unitary timing process, the distinct timing hypothesis suggests two dissociable, independent mechanisms for the timing of intervals in the sub-second and the second range, respectively. In the present paper, we introduce confirmatory factor analysis (CFA) to elucidate the internal structure of interval timing in the sub-second and the second range. Our results indicate that the assumption of two mechanisms underlying the processing of intervals in the second and the sub-second range might be more appropriate than the assumption of a unitary timing mechanism. In contrast to the basic assumption of the distinct timing hypothesis, however, these two timing mechanisms are closely associated with each other and share 77% of common variance. This finding suggests either a strong functional relationship between the two timing mechanisms or a hierarchically organized internal structure. Findings are discussed in the light of existing psychophysical and neurophysiological data.

Development of time sensitivity and information processing speed

The aim of this study was to examine whether age-related changes in the speed of information processing are the best predictors of the increase in sensitivity to time throughout childhood. Children aged 5 and 8 years old, as well adults, were given two temporal bisection tasks, one with short (0.5/1-s) and the other with longer (4/8-s) anchor durations. In addition, the participants' scores on different neuropsychological tests assessing both information processing speed and other dimensions of cognitive control (short-term memory, working memory, selective attention) were calculated. The results showed that the best predictor of individual variances in sensitivity to time was information processing speed, although working memory also accounted for some of the individual differences in time sensitivity, albeit to a lesser extent. In sum, the faster the information processing speed of the participants, the higher their sensitivity to time was. These results are discussed in the light of the idea that the development of temporal capacities has its roots in the maturation of the dynamic functioning of the brain.

Individual differences in motor timing and its relation to cognitive and fine motor skills

The present study investigated the relationship between individual differences in timing movements at the level of milliseconds and performance on selected cognitive and fine motor skills. For this purpose, young adult participants (N = 100) performed a repetitive movement task paced by an auditory metronome at different rates. Psychometric measures included the digit-span and symbol search subtasks from the Wechsler battery as well as the Raven SPM. Fine motor skills were assessed with the Purdue Pegboard test. Motor timing performance was significantly related (mean r = .3) to cognitive measures, and explained both unique and shared variance with information-processing speed of Raven's scores. No significant relations were found between motor timing measures and fine motor skills. These results show that individual differences in cognitive and motor timing performance is to some extent dependent upon shared processing not associated with individual differences in manual dexterity.

Developing a Psychophysical Measure to Assess Duration Discrimination in the Millisecond Range

Duration discrimination in the range of milliseconds is essential for various aspects of behavior and individual differences. The present paper addresses important methodological issues, such as type of stimuli, type of task, method for threshold estimation, and temporal sensitivity of the psychophysical procedure, that should be borne in mind when developing a sensitive and reliable duration discrimination task. Furthermore, it introduces a psychophysical approach for the assessment of individual differences in duration discrimination of extremely brief intervals in the subsecond range. Monte Carlo simulations provide clear evidence that this task is sensitive enough to correctly detect a true difference between temporal stimuli as small as 2 ms with a high probability. Further, the distributional properties of individual performance scores obtained from 534 participants by means of the introduced duration discrimination task are presented.

Lapsed attention to elapsed time? Individual differences in working memory capacity and temporal reproduction

Working memory capacity (WMC) predicts individual differences in a wide range of mental abilities. In three experiments we examined whether WMC would predict temporal judgment. Low-WMC temporal reproductions were consistently too long for the shortest duration and too short for the longest, but were accurate (unbiased) for the intermediate. In contrast, high-WMC temporal reproductions were more accurate (unbiased) across the range. Thus low-WMC showed a classic "migration effect" (Vierordt's Law) to a greater extent than high-WMC. Furthermore reproduction errors depended more on temporal context than the absolute durations of "shortest," "longest," and "intermediate." Low-WMC reproductions were overall more variable than high-WMC. General fluid intelligence (gF) was also related to temporal bias and variability. However, WMC-related timing differences were only attenuated and not eliminated with gF as covariate. Results are discussed in terms of attention, memory, and other psychological constructs.

Elaborative rehearsal of nontemporal information interferes with temporal processing of durations in the range of seconds but not milliseconds

The distinct timing hypothesis suggests a sensory mechanism for processing of durations in the range of milliseconds and a cognitively controlled mechanism for processing of longer durations. To test this hypothesis, we employed a dual-task approach to investigate the effects of maintenance and elaborative rehearsal on temporal processing of brief and long durations. Unlike mere maintenance rehearsal, elaborative rehearsal as a secondary task involved transfer of information from working to long-term memory and elaboration of information to enhance storage in long-term memory. Duration discrimination of brief intervals was not affected by a secondary cognitive task that required either maintenance or elaborative rehearsal. Concurrent elaborative rehearsal, however, impaired discrimination of longer durations as compared to maintenance rehearsal and a control condition with no secondary task. These findings endorse the distinct timing hypothesis and are in line with the notion that executive functions, such as continuous memory updating and active transfer of information into long-term memory interfere with temporal processing of durations in the second, but not in the millisecond range.

Auditory and visual temporal sensitivity: evidence for a hierarchical structure of modality-specific and modality-independent levels of temporal information processing

The present study investigated modality-specific differences in processing of temporal information in the subsecond range. For this purpose, participants performed auditory and visual versions of a rhythm perception and three different duration discrimination tasks to allow for a direct, systematic comparison across both sensory modalities. Our findings clearly indicate higher temporal sensitivity in the auditory than in the visual domain irrespective of type of timing task. To further evaluate whether there is evidence for a common modality-independent timing mechanism or for multiple modality-specific mechanisms, we used structural equation modeling to test three different theoretical models. Neither a single modality-independent timing mechanism, nor two independent modality-specific timing mechanisms fitted the empirical data. Rather, the data are well described by a hierarchical model with modality-specific visual and auditory temporal processing at a first level and a modality-independent processing system at a second level of the hierarchy.

Processing Visual Temporal Information and Its Relationship to Psychometric Intelligence

According to previous studies there is a well-established functional relationship between temporal resolution power (TRP), assessed by auditory psychophysical timing tasks, and psychometric intelligence. Here we investigated whether the relationship between psychometric intelligence and temporal information processing can be also observed in the visual modality. For this purpose, performance on four visual psychophysical timing tasks (duration discrimination with filled and empty intervals, temporal generalization, and rhythm perception) was examined and related to performance on a psychometric test of intelligence. Correlational analyses indicated a reliable positive association between performance on each of the four temporal tasks and psychometric intelligence. Structural equation modeling suggested that performance on the four tasks can be assigned to one latent variable, referred to as TRP, which explained 16.5% of variance of psychometric intelligence. Findings indicate that the functional relationship previously observed between auditory temporal processing and psychometric intelligence can be generalized to the visual modality.

Processing of Temporal and Nontemporal Information as Predictors of Psychometric Intelligence: A Structural-Equation-Modeling Approach

Recent research suggests a functional link between temporal acuity and general intelligence. To better understand this relation, the present study took advantage of a large sample (N=260) and structural equation modelling to examine relations among temporal acuity, measured by various tasks, speed of information processing as measured by the Hick reaction time task, and psychometric intelligence. Temporal acuity and the Hick task showed common variance in predicting psychometric intelligence. Furthermore, timing performance was a better predictor of psychometric intelligence and mediated the relation between Hick task performance and psychometric intelligence. These findings are consistent with the idea that temporal acuity reflects a basic property of neural functioning that is relevant to intelligence-related aspects of mental activity including speed of information processing.

Timing Performance as a Predictor of Psychometric Intelligence as Measured by Speed and Power Tests

In the present study, the relationship between timing performance and psychometric intelligence as measured by a speed and a power test of intelligence was examined. For this purpose performance on the Zahlen-Verbindungs-Test (ZVT), the Wiener Matrizen-Test (WMT), seven psychophysical temporal tasks, and the Hick reaction-time paradigm was obtained in 190 participants. Correlational and principal component analyses suggested a unitary timing mechanism referred to as temporal g. Performance on single temporal tasks and individual factor scores on temporal g were substantially related to both speed and power measures of psychometric intelligence. Temporal g exhibited higher sensitivity to the prediction of performance on the power test than on the speed test. Furthermore, stepwise multiple regression analysis and commonality analysis revealed that timing performance provides a more powerful predictor of psychometric intelligence than traditional reaction-time measures derived from the Hick paradigm. These findings support the notion that the temporal resolution capacity of the brain as assessed with psychophysical temporal tasks reflects an essential property of brain functioning, which is relevant to a wide range of intelligence-related aspects of neural information processing.

Age-Related Cognitive Slowing: The Role of Spontaneous Tempo and Processing Speed

This research studied the relationships between two types of slowing observed in aging-loss of general processing speed and slowing of spontaneous tempo-in an attempt to test the assumption that there is an internal timing mechanism responsible for cognitive age-related decrease. Processing speed has been evaluated as a mediator of the relationship between age and working memory, concurrently with spontaneous tempo measures. The authors compared the performance of young and older adults on tasks involving spontaneous motor tempo, processing speed, and working memory. The findings confirmed the agerelated slowing of spontaneous motor tempo but did not indicate superiority of tempo mediation in the decline in working memory. Processing speed appeared to be a major mediator of working memory, but also of spontaneous tempo slowing.