Pierre-Luc Gamache

The Structure of Sensory Events and the Accuracy of Time Judgments

We investigated how does the structure of empty time intervals influence temporal processing. In experiment 1, the intervals to be discriminated were the silent durations marked by two sensory signals, both lasting 10 or 500 ms; these signals were two identical flashes (intramodal: VV), or one visual flash (V) followed by an auditory tone (A) (intermodal: VA). For the range of duration under investigation (standards = 0.2, 0.6, 1, or 1.4 s), the results indicated that both the marker length and sensory mode influenced discrimination, but no interaction between these variables or between one of these variables and standard duration was significant. In experiment 2, we compared, for each of four marker-type conditions (VV, AA, VA, AV; and standard = 1 s), intervals marked by two 10 ms signals with intervals marked by unequal signal length (markers 1 and 2 lasting 10 and 500 ms, or 500 and 10 ms). As in experiment 1, the results revealed significant marker-mode and marker-length effects, but no significant interaction between these variables. Experiment 3 showed that, for the same conditions as in experiment 2, perceived duration is not influenced by marker length and that the variability of interval reproductions does not depend on the perceived duration of intervals. The results are discussed in the light of a single-clock hypothesis: marker-length and marker-mode effects are presented as being non-temporal sources of variability associated mainly with sensory and memory processes.

Sensory‐specific clock components and memory mechanisms: investigation with parallel timing

A challenge for researchers in the time‐perception field is to determine whether temporal processing is governed by a central mechanism or by multiple mechanisms working in concert. Behavioral studies of parallel timing offer interesting insights into the question, although the conclusions fail to converge. Most of these studies focus on the number‐of‐clocks issue, but the commonality of memory mechanisms involved in time processing is often neglected. The present experiment aims to address a straightforward question: do signals from different modalities marking time intervals share the same clock and/or the same memory resources? To this end, an interval reproduction task involving the parallel timing of two sensory signals presented either in the same modality or in different modalities was conducted. The memory component was tested by manipulating the delay separating the presentation of the target intervals and the moment when the reproduction of one of these began. Results show that there is more variance when only visually marked intervals are presented, and this effect is exacerbated with longer retention delays. Finally, when there is only one interval to process, encoding the interval with signals delivered from two modalities helps to reduce variance. Taken together, these results suggest that the hypothesis stating that there are sensory‐specific clock components and memory mechanisms is viable.

Alternative Avenues in the Assessment of Driving Capacities in Older Drivers and Implications for Training

The aging of the population, combined with the overrepresentation of older drivers in car crashes, has engendered a whole body of research destined at finding simple and efficient assessment methods of driving capacities. Such a search is destined to fail, given that car crashes and unsafe driving behaviors can result from myriad interacting factors. This review highlights the main problems of the current assessment methods and training programs and presents theoretical and empirical arguments justifying the need of reorienting the research focus. In our discussion, we elaborate the fundamental principle of specificity in learning and practice. We also identify overlooked variables that are deterministic when assessing and training a complex ability like driving. We especially focus on the role of the sensorimotor transformation process. Finally, we propose alternative methods of assessment and training that, in line with recent trends in education, use virtual reality and simulation technologies.

The Lifespan of Time Intervals in Reference Memory

To further explore how memory influences time judgments, we conducted two experiments on the lifespan of temporal representations in memory. Penney et al (2000, Journal of Experimental Psychology: Human Perception and Performance 26 1770 – 1787) reported that the perceived duration of auditorily and visually marked intervals differs only when both marker-type intervals are compared directly. This finding can be explained by a ‘memory-mixing’ process, whereby the memory trace of previous intervals influences the perception of upcoming ones, which are then added to the memory content. In the experiments discussed here, we manipulated the mixing mode of auditory/visual signal presentations. In experiment 1, signals from the same modality were either grouped by blocks or randomised within blocks. The results showed that the auditory/visual difference decreased but remained present when modalities were grouped by blocks. In experiment 2, we used a line-segmentation task. The results showed that, after a training block was performed in one modality, the perceived duration of signals from the other modality was distorted for at least 30 trials and that the magnitude of the difference decreased as the block went on. The results of both experiments highlight the influence of memory on time judgments, providing empirical support to, and quantitative portrayal of, the memory-mixing process.

In-simulator training of driving abilities in a person with a traumatic brain injury

Aim: This study reports the case of a 23-year-old woman (MC) who sustained a severe traumatic brain injury in 2004. After her accident, her driving license was revoked. Despite recovering normal neuropsychological functions in the following years, MC was unable to renew her license, failing four on-road evaluations assessing her fitness to drive. Method: In hope of an eventual license renewal, MC went through an in-simulator training programme in the laboratory in 2009. The training programme aimed at improving features of MCs driving behaviour that were identified as being problematic in prior on-road evaluations. To do so, proper driving behaviour was reinforced via driving-specific feedback provided during the training sessions. Results: After 25 sessions in the simulator (over a period of 4 months), MC significantly improved various components of her driving. Notably, compared to early sessions, later ones were associated with a reduced cognitive load, less jerky speed profiles when stopping at intersections and better vehicle control and positioning. A 1-year retention test showed most of these improvements were consistent. Conclusions: The learning principles underlying well conducted simulator-based education programmes have a strong scientific basis. A simulator training programme like this one represents a promising avenue for driving rehabilitation. It allows individuals without a driving license to practice and improve their skills in a safe and realistic environment.

Using Time-Processing Skills to Predict Reading Abilities in Elementary School Children

This article aims at examining the relationship between temporal skills and reading. According to Tallal, dyslexia may be linked to a global deficit in temporal processing, which would be detrimental for discrimination of phonemes, and thus impair reading acquisition. The temporal deficit hypothesis is not consensual, and the exact nature of the temporal deficits assumed to be associated with dyslexia remains unknown. The aim of the present experiment is to better define the temporal processes involved in reading. To do so, elementary school children from 1st to 6th grade with varied reading skills levels were recruited (from weak to very good readers). Each participant performed four temporal tasks, that is, gap detection, temporal order judgement, interval discrimination and interval reproduction; and each task was performed in two different conditions, i.e., with signals marking time delivered in the visual and in the auditory modalities. The results show positive correlations between reading skills and all temporal tasks, in both modalities. We also established a prediction model of reading skills with visual gap detection sensitivity as the best predictor. The results support Tallal’s theory. Temporal deficits in weak readers are global and transcend sensory modalities. The gap detection task in the visual modality shows clinical potential for identifying timing-related reading difficulties, and could be used in future research.