More consistent,yet less sensitive: Interval timing in autism spectrum disorders

Even though phenomenological observations and anecdotal reports suggest atypical time processing in individuals with an autism spectrum disorder (ASD), very few psychophysical studies have investigated interval timing, and the obtained results are contradictory. The present study aimed to clarify which timing processes function atypically in ASD and whether they are related to the ASD diagnostic profile. Visual, auditory, and cross-modal interval timing was assessed in 18 individuals with ASD using a repeated standards version of the temporal generalization task. The use of two different standard durations (600 and 1,000 ms) allowed for an assessment of the scalar property of interval timing in ASD, a fundamental characteristic of interval timing. The ASD group showed clearer adherence to the scalar property of interval timing than the control group. In addition, both groups showed the normal effect that auditory stimuli had longer subjective durations than visual ones. Yet, signal detection analysis showed that the sensitivity of temporal discrimination was reduced in the ASD group across modalities, in particular for auditory standards. Moreover, response criteria in the ASD group were related to symptom strength in the communication domain. The findings suggest that temporal intervals are fundamentally processed in the same way in ASD and TD, but with reduced sensitivity for temporal interval differences in ASD. Individuals with ASD may show a more conservative response strategy due to generally decreased sensitivity for the perception of time intervals.     

Vierordt's The Experimental Study of the Time Sense (1868) and its legacy

The paper discusses the results from Vierordt's 1868 book Der Zeitsinn nach Versuchen [The Experimental Study of the Time Sense]. Illustrations of “Vierordt's Law”, the proposition that short durations are judged as longer than they really are, whereas long durations are judged as shorter, with an “indifference point” in between, are provided, mainly from reproduction experiments where Vierordt and his students or colleagues served as experimental participants. Other work from Der Zeitsinn including time discrimination and categorical timing procedures is also presented. Some subsequent research on Vierordt's Law and the “indifference point” is discussed with respect to some issues in contemporary timing theory.     

Interval timing predicts impulsivity in intertemporal choice: combined behavioral and drift-diffusion model evidence

ABSTRACT

This study investigated the relationship between interval timing and impulsivity in intertemporal choice in a healthy population. A duration production task was used to assess interval timing. Choice impulsivity was assessed using a hypothetical money choice task. Results from 134 participants indicated that faster internal clock significantly predicted lower choice impulsivity. A subsequent drift-diffusion model analysis of the behavioural data revealed that in the sub-group of relatively farsighted participants, faster internal clock predicted consideration of more information before making a choice, which in turn was associated with lower choice impulsivity. In the sub-group of relatively impatient participants too, faster internal clock predicted consideration of more information, but which in turn was associated with higher choice impulsivity. It is concluded that among relatively farsighted individuals in a normal population, faster internal clock favours a more deliberate processing of the options at hand, thus eliciting less impulsive choices.     

Temporal Precision in Tapping and Circle Drawing Movements at Preferred Rates is Not Correlated: Further Evidence Against Timing as a General-Purpose Ability

Recently, researchers have discovered that individuals who are consistent timers in a tapping task are not necessarily consistent timers when they perform a continuous drawing task. In other words, nonsignificant correlations were found among tapping and drawing movements for timing precision (S. D. Robertson et al., 1999). In the present experiment, the authors investigated whether or not consistency in timing for tapping and drawing was correlated when participants (N = 24) were allowed to move at their preferred rate of movement. There were no significant correlations between tapping and drawing in terms of timing precision. That result lends further support to the notion that timing behavior is specific to the nature of the task, and thus further weakens the idea that timing is a generalized ability that can be imposed on a variety of different types of tasks.     

Force and Timing Variability in Rhythmic Unimanual Tapping

In 3 experiments the interdependencies between timing and force production in unimanual paced and self-paced rhythmic tapping tasks were examined as participants (N = 6 in each experiment) tapped (a) to 1 of 3 target periods (333 ms, 500 ms, and 1,000 ms), while they simultaneously produced a constant peak force (PF) over a 50-s trial; (b) to produce 1 of 3 target forces (5, 10, and 15 N) at their preferred frequency, while keeping their rhythm as invariant as possible; and (c) to all combinations of target force and period. The results showed that (a) magnitudes of force and period were largely independent; (b) variability in timing increased proportionally with tapping period, and the variability in force increased with peak force; (c) force variability decreased at faster tapping rates; and (d) timing variability decreased with increasing force levels, (e) Analysis of tap-to-tap variability revealed adjustments over sequences of taps and an acceleration in the tapping rate in unpaced conditions. The interdependencies of force and time are discussed with respect to the challenges they provide for an oscillator-based account.     

Planning and Executing Simple Movements: Contributions of Relative-Time and Overall-Duration Specification

In 3 experiments, the authors used a precuing protocol to examine the nature and cost of programming and the subsequent reprogramming of a movement's relative time and overall duration. Initial programming followed a fixed-order specification; knowledge of the necessary relative time was required before information regarding overall duration could be used in a manner that expedited response planning. In the case of reprogramming, however, when a modification had to be made in either the relative time or overall duration of the anticipated and already-prepared response, performers chose to completely reprogram the entire response. Complete reprogramming occurred even when the performer had correctly prepared the higher order relative-time component and only had to modify the overall duration of the movement. The data indicate that organizing movement timing before movement initiation is accomplished in a fundamentally different manner depending on whether the movement is being initially compiled or modified.     

Pattern Stability and Error Correction During In-Phase and Antiphase Four-Ball Juggling

The authors studied pattern stability and error correction during in-phase and antiphase 4-ball fountain juggling. To obtain ball trajectories, they made and digitized high-speed film recordings of 4 highly skilled participants juggling at 3 different heights (and thus different frequencies). From those ball trajectories, the authors determined and analyzed critical events (i.e., toss, zenith, catch, and toss onset) in terms of variability of point estimates of relative phase and temporal correlations. Contrary to common findings on basic instances of rhythmic interlimb coordination, in-phase and antiphase patterns were equally variable (i.e., stable). Consistent with previous findings, however, pattern stability decreased with increasing frequency. In contrast to previous results for 3-ball cascade juggling, negative lag-one correlations for catch-catch intervals were absent, but the authors obtained evidence for error corrections between catches and toss onsets. That finding may have reflected participants' high skill level, which yielded smaller errors that allowed for corrections later in the hand cycle.     

Continuous and Discontinuous Drawing: High Temporal Variability Exists Only in Discontinuous Circling in Young Children

The authors studied whether the drawing variability in young children is best explicable by (a) demands on the explicit timing system, (b) an underdeveloped ability to control limb dynamics, or (c) both. The explicit timing demands were lower in continuous drawing in comparison with the discontinuous task. The authors manipulated limb dynamics by changing the number of joints involved, with line drawing requiring fewer joints than circle drawing. Results showed that young children had high temporal variability in discontinuous circling but not in other conditions. The authors argue that both explicit timing and dynamic complexity of limb control may be determinants of temporal consistency and may thus play an important role in the development of drawing and writing skills in children.     

Negotiating time: the significance of timing in ending inpatient work

This paper discusses work with young people during their stay on an NHS psychiatric inpatient unit, especially focusing on the end of treatment and the appropriate timing of discharge into the community. When approaching the end of an admission, various factors are considered that seem particularly relevant to the decision of when a young person may be ready to leave and cope with the transition back to life outside the unit. Indications of medical stability, in patients where this has been an issue, is a factor of prime importance. Other important factors include family functioning; the availability of adequate ongoing local CAMHS support for the child and family; suitable school provision; and the identity of the child within a peer group. The reality of NHS resources and the demand for inpatient beds is another pressing consideration. The young person's own motivation emerges as crucial at this stage – towards the end of treatment – not only in terms of what is said, and therefore evident verbally, but also through signs of internal shifts in the child that indicate a capacity to re-engage with life outside in a lasting way. Decisions about when to stop are taken with all this in mind and when the decision does not seem straightforward, it can provoke considerable anxiety in the multi-disciplinary team. Clinical material from psychotherapy with a young adolescent boy with anorexia nervosa is used to illustrate some of the dilemmas.