People who are more aware of their own heart-beat have superior time perception skills

What underlies our sense of time? A popular account claims an internal pacemaker emits regular pulses, which are detected by an accumulator. The amount of accumulated pulses represents the amount of time that's passed.

Trouble is, this is all very theoretical and no-one really knows how or where in the brain these functions are enacted. One suggestion is that the pulses are based on bodily feedback and in particular the heart-beat. Consistent with this is a recent brain imaging study that showed activity in the insular (a brain region associated with representing internal bodily states) rose linearly as people paid attention to time intervals (pdf). Now a behavioural study by Karin Meissner and Marc Wittmann has built on these findings by showing that people who are more sensitive to their own heart-beat are also better at judging time intervals.

Thirty-one participants listened to auditory tones of either 8, 14, or 20 seconds duration. After each one, they heard a second tone and had to press a button when they thought its duration matched the first. Counting was forbidden during the task and a secondary, number-based memory task helped enforce this rule. Heart-beat perception accuracy was measured separately and simply involved participants counting silently their own heart-beats over periods of 25, 35, 45 and 60 seconds.

The take away message is that the participants who were more in tune with their heart-beats also tended to perform better at the time estimation task. A further detail is that physiological measures taken during the encoding part of the task showed that as time went on, the participants' heart-rate slowed progressively, and their skin conductance (i.e. amount of sweat on the skin) reduced. Moreover, the rate of change in a participant's heart-rate (but not skin conductance) was linked with the accuracy of their subsequent time estimates.

'These results suggest that the processing of interoceptive signals [i.e. of internal bodily states] in the brain might contribute to our sense of time,' Meissner and Wittmann concluded.

The new findings add to past research showing that patients with cardiac arrhythmia are poorer than controls at time estimation tasks, and that drug-induced speeding or slowing of the autonomic nervous system (including heart-rate) affects people's under- or over-estimation of time intervals.
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Meissner, K., and Wittmann, M. (2011). Body signals, cardiac awareness, and the perception of time. Biological Psychology, 86 (3), 289-297 DOI: 10.1016/j.biopsycho.2011.01.001

Tourette's Syndrome associated with superior timing control

Children with Tourette's Syndrome, the neurodevelopmental condition characterised by involuntary motor and verbal tics, have superior timing abilities compared with their healthy age-matched peers, a new study suggests.

Carmelo Vicario and colleagues tested nine children with Tourette's (average age 11 years) and 10 controls (average age 12) on timing perception and timing production. The former involved the children judging whether two circles were on screen for the same length of time or not. The latter task involved the children noting the time that a circle appeared on-screen and then pressing the space key on a key board for the same duration. Half the trials involved intervals in the sub-second range (from 310ms to 500ms), the other half were longer than a second, up to 1900ms.

There was no difference between the groups on timing perception or sub-second timing production. However, the children with Tourette's were more accurate at the longer 'supra-second' version of the timing production task.

Vicario's team aren't entirely sure why the children with Tourette's showed this advantage. However, past research suggests that tic suppression is associated with activity in the dorsolateral prefrontal cortex and the supplementary area - two areas which are also known to be involved in control of timing. Consistent with this, the children with less severe tics, perhaps by virtue of their greater control over those tics, also tended to be the children who most excelled at the timing production task.

The children were also tested on other factors that could be relevant, including attention and working memory, but scores on these tasks didn't correlate with performance on the timing tasks.

This new finding of enhanced timing control in Tourette's comes after a 2006 study that found children with the condition exhibited superior self-control in an eye-movement task. A study published in 2007, meanwhile, reported Tourette's was associated with superior grammatical abilities.

'The present data are in support of an enhancement of cognitive control processes in Tourette's Syndrome children, probably facilitated by effortful tic suppression,' the researchers said.
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Vicario, C., Martino, D., Spata, F., Defazio, G., Giacchè, R., Martino, V., Rappo, G., Pepi, A., Silvestri, P., & Cardona, F. (2010). Time processing in children with Tourette’s syndrome. Brain and Cognition, 73 (1), 28-34 DOI: 10.1016/j.bandc.2010.01.008