Search

Intelligence and cognitive ability have long been associated with chronometric performance measures, such as reaction time (RT), but few studies have investigated auditory RT in this context. The nature of this relationship is important for understanding the etiology and structure of intelligence. Here, we present a bivariate twin analysis of simple auditory RT and psychometric intelligence (measured by the Wiener Matrizen Test). The sample consisted of 1,816 complete twin pairs and 4623 singletons enrolled in the Swedish Twin Registry, who performed the tests online. The heritabilities were 0.54 and 0.21 for intelligence and RT, respectively, and the phenotypic correlation was −0.17, 47% of which was explained by common genetic variance. These results are comparable to those found for visual RT and for other cognitive tests, and add RT in the auditory modality to the small literature on common genetic influences across intelligence and other cognitive and chronometric variables. [ABSTRACT FROM AUTHOR]

The origins of the ability to produce action at will at the hundreds of millisecond to second range remain poorly understood. A central issue is whether such timing is governed by one mechanism or by several different mechanisms, possibly invoked by different effectors used to perform the timing task. If two effectors invoke similar timing mechanisms, then they should both produce similar variability increase with interval duration (interonset interval) and thus adhere to Weber's law (increasing linearly with the duration of the interval to be timed). Additionally, if both effectors invoke the same timing mechanism, the variability of the effectors should be highly correlated across participants. To test these possibilities, we assessed the behavioural characteristics across fingers and eyes as effectors and compared the timing variability between and within them as a function of the interval to be produced (interresponse interval). Sixty participants produced isochronous intervals from 524 to 1431 ms with their fingers and their eyes. High correlations within each effector indicated consistent performance within participants. Consistent with a single mechanism, temporal variability in both fingers and eyes followed Weber's law, and significant correlations between eye and finger variability were found for several intervals. These results can support neither the single clock nor the multiple clock hypotheses but instead suggest a partially overlapping distributed timing system. [ABSTRACT FROM PUBLISHER]

Music performance depends critically on precise processing of time. A common model behavior in studies of motor timing is isochronous serial interval production (ISIP), that is, hand/finger movements with a regular beat. ISIP accuracy is related to both music practice and intelligence. Here we present a study of these associations in a large twin cohort, demonstrating that the effects of music practice and intelligence on motor timing are additive, with no significant multiplicative (interaction) effect. Furthermore, the association between music practice and motor timing was analyzed with the use of a co-twin control design using intrapair differences. These analyses revealed that the phenotypic association disappeared when all genetic and common environmental factors were controlled. This suggests that the observed association may not reflect a causal effect of music practice on ISIP performance but rather reflect common influences (e.g., genetic effects) on both outcomes. The relevance of these findings for models of practice and expert performance is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Timing performance becomes less precise for longer intervals, which makes it difficult to achieve simultaneity in synchronisation with a rhythm. The metrical structure of music, characterised by hierarchical levels of binary or ternary subdivisions of time, may function to increase precision by providing additional timing information when the subdivisions are explicit. This hypothesis was tested by comparing synchronisation performance across different numbers of metrical levels conveyed by loudness of sounds, such that the slowest level was loudest and the fastest was softest. Fifteen participants moved their hand with one of 9 inter-beat intervals (IBIs) ranging from 524 to 3125ms in 4 metrical level (ML) conditions ranging from 1 (one movement for each sound) to 4 (one movement for every 8th sound). The lowest relative variability (SD/IBI<1.5%) was obtained for the 3 longest IBIs (1600–3125ms) and MLs 3–4, significantly less than the smallest value (4–5% at 524–1024ms) for any ML 1 condition in which all sounds are identical. Asynchronies were also more negative with higher ML. In conclusion, metrical subdivision provides information that facilitates temporal performance, which suggests an underlying neural multi-level mechanism capable of integrating information across levels. [Copyright &y& Elsevier]

Abstract: Timing permeates everyday activities such as walking, dancing and music, yet the effect of short-term practice in this ubiquitous activity is largely unknown. In two training experiments involving sessions spread across several days, we examined short-term practice effects on timing variability in a sequential interval production task. In Experiment 1, we varied the mode of response (e.g., drumstick and finger tapping) and the level of sensory feedback. In Experiment 2 we varied the interval in 18 levels ranging from 500ms to 1624ms. Both experiments showed a substantial decrease in variability within the first hour of practice, but little thereafter. This effect was similar across mode of response, amount of feedback, and interval duration, and was manifested as a reduction in both local variability (between neighboring intervals) and drift (fluctuation across multiple intervals). The results suggest mainly effects on motor implementation rather than on cognitive timing processes, and have methodological implications for timing studies that have not controlled for practice. [Copyright &y& Elsevier]

Abstract: Psychometric intelligence correlates with reaction time in elementary cognitive tasks, as well as with performance in time discrimination and judgment tasks. It has remained unclear, however, to what extent these correlations are due to top–down mechanisms, such as attention, and bottom–up mechanisms, i.e. basic neural properties that influence both temporal accuracy and cognitive processes. Here, we assessed correlations between intelligence (Raven SPM Plus) and performance in isochronous serial interval production, a simple, automatic timing task where participants first make movements in synchrony with an isochronous sequence of sounds and then continue with self-paced production to produce a sequence of intervals with the same inter-onset interval (IOI). The target IOI varied across trials. A number of different measures of timing variability were considered, all negatively correlated with intelligence. Across all stimulus IOIs, local interval-to-interval variability correlated more strongly with intelligence than drift, i.e. gradual changes in response IOI. The strongest correlations with intelligence were found for IOIs between 400 and 900 ms, rather than above 1 s, which is typically considered a lower limit for cognitive timing. Furthermore, poor trials, i.e. trials arguably most affected by lapses in attention, did not predict intelligence better than the most accurate trials. We discuss these results in relation to the human timing literature, and argue that they support a bottom–up model of the relation between temporal variability of neural activity and intelligence. [Copyright &y& Elsevier]

We show that people continuously react to time perturbations in the range 3–96 ms in otherwise isochronous sound sequences. Musically trained and untrained participants were asked to synchronize with a sequence of sounds, and these two groups performed almost equally below the threshold for conscious detection of the perturbations. Above this threshold the motor reactions accounted for a larger proportion of the stimulus deviations in musically trained participants. [Copyright &y& Elsevier]

Three experiments determined the perceptual threshold (JND) for detecting tempo change; i.e. linear continuous increase or decrease in inter onset interval (IOI) in sequences with 2–9 brief sounds. JND decreased as a power function of the number of intervals presented (Expt. 1). JND increased with IOI and exhibited breakpoints in this respect close to 1 and 1.4 s (Expt. 3), in agreement with previous results for serial interval production. No interaction was apparent between IOI and number of intervals (Expt. 2). None of the experiments showed any effect of direction (increasing or decreasing intervals). The results are inconsistent with several conceivable principles for perceiving tempo change, except for one in which the external intervals are compared with the intervals generated by an internal, periodic process. The plausibility of this principle is discussed in the light of recent research on sensorimotor synchronisation. [Copyright &y& Elsevier]

Psychometric intelligence correlates with performance on a wide range of sensory and motor tasks that involve processing of temporal information in the millisecond-second range. For some timing tasks, e.g. reaction time and discrimination of temporal stimuli in working memory, the associations with intelligence are likely to involve top–down mechanisms such as attention. However, studies on repetitive, automatic motor timing tasks indicate that correlations between intelligence and timing also may reflect bottom-up mechanisms, i.e. basic neural properties that influence both the temporal accuracy of behavior and cognitive processes. Here, we study the genetic architecture of the associations between intelligence, perceptual timing (auditory rhythm discrimination) and motor timing (finger tapping) in a large twin cohort. Specifically, we hypothesized that the associations between these tasks on the phenotypic level involve broad pleiotropic genetic effects that influence all three tasks, as well as additional genetic effects on the covariation between perceptual and motor timing. Phenotypic associations between the variables were low to moderate, with Pearson's correlations in the range 0.17–0.32. Trivariate twin modeling showed that the associations between the three variables were essentially due to shared genetic influences. In support of the hypotheses, we found evidence for pleiotropic effects on motor timing, perceptual timing, and intelligence, as well as additional genetic covariation between the two timing tasks that was not shared with intelligence. We conclude, first, that genetic factors underlying intelligence may involve genes which influence brain properties of importance for the temporal accuracy of neural processing. We discuss possible neural substrates of such effects. Secondly, the correlation between motor and perceptual timing also partly explained by genetic influences that are unrelated to intelligence. [ABSTRACT FROM AUTHOR]

We investigated the causal role of executive control functions in the production of brief time intervals by means of a concurrent task paradigm. To isolate the influence of executive functions on timing from motor coordination effects, we dissociated executive load from the number of effectors used in the dual task situation. In 3 experiments, participants produced isochronous intervals ranging from 524 to 2,000 ms with either the left or the right hand. The concurrent task consisted of the production of either a pseudorandom (high cognitive load) or a simple repeated (low cognitive load) spatial sequence of key presses, while also maintaining a regular temporal sequence. This task was performed with either a single hand (unimanual) or with both hands simultaneously (bimanual). Interference in terms of increased timing variability caused by the concurrent task was observed only in the bimanual condition. We verified that motor coordination in bimanual tasks alone could not account for the interference. Timing interference only appeared when (a) more than 1 effector was involved and (b) there were simultaneous task demands that recruited executive functions. Task interference was not seen if only 1 of these 2 conditions was met. Thus, our results suggest that executive functions are not directly involved in motor timing, but can indirectly affect timing performance when they are required to schedule complex motor coordination. [ABSTRACT FROM AUTHOR]

Abstract: Intelligence correlates with accuracy in various timing tasks. Such correlations could be due to both bottom–up mechanisms, e.g. neural properties that influence both temporal accuracy and cognitive processing, and differences in top–down control. We have investigated the timing–intelligence relation using a simple temporal motor task, isochronous serial interval production (ISIP), i.e. hand/finger movements with a regular beat. ISIP variability is negatively correlated with intelligence and we have previously argued, based on indirect evidence, that this relation has a bottom–up component. Here, we investigate this question using an experimental within-subject design in two samples (n=38 and n=95 participants, respectively). ISIP was performed under two conditions. In the first condition (Low Motivation), the participants were told that measurements were being made to familiarize them with the task and to calibrate the equipment. In the second condition (High Motivation), the participants were told that the performance would be evaluated and used for scientific analysis, and they were given a monetary reward depending on how accurately they performed. Temporal accuracy in the ISIP was higher during High Motivation than during Low Motivation. In both samples, correlations between ISIP variability and intelligence were similar for both conditions. General linear models with ISIP variability measures as dependent variables, condition (Low Motivation or High Motivation) as a repeated-measures variable and intelligence as a between-subject variable, revealed a significant effect of intelligence, but no effects of incentive, nor of the intelligence×incentive interaction. We conclude that motivationally driven top–down mechanisms can influence ISIP performance, but that they play no major role for correlations between temporal accuracy in ISIP and intelligence. These results provide further support for that bottom–up mechanisms are involved in relations between temporal accuracy and intelligence. [Copyright &y& Elsevier]