Nicolas Bisson

An Ecological Approach to Prospective and Retrospective Timing of Long Durations: A Study Involving Gamers

To date, most studies comparing prospective and retrospective timing have failed to use long durations and tasks with a certain degree of ecological validity. The present study assessed the effect of the timing paradigm on playing video games in a “naturalistic environment” (gaming centers). In addition, as it involved gamers, it provided an opportunity to examine the effect of gaming profile on time estimation. A total of 116 participants were asked to estimate prospectively or retrospectively a video game session lasting 12, 35 or 58 minutes. The results indicate that time is perceived as longer in the prospective paradigm than in the retrospective one, although the variability of estimates is the same. Moreover, the 12-minute session was perceived as longer, proportionally, than the 35- and 58-minute sessions. The study also revealed that the number of hours participants spent playing video games per week was a significant predictor of time estimates. To account for the main findings, the differences between prospective and retrospective timing are discussed in quantitative terms using a proposed theoretical framework, which states that both paradigms use the same cognitive processes, but in different proportions. Finally, the hypothesis that gamers play more because they underestimate time is also discussed.

Prospective and retrospective time estimates of children: a comparison based on ecological tasks.

Childrens time estimation literature lacks of studies comparing prospective and retrospective time estimates of long lasting ecological tasks, i.e. tasks reflecting childrens daily activities. In the present study, children were asked to estimate prospectively or retrospectively how much time they played a video game or read a magazine. Regardless of the task, the results revealed that prospective time estimates were longer than the retrospective ones. Also, time estimates of the video game task were longer, less accurate and more variable than those of the reading task. The results are discussed in the light of the current literature about time estimation of long lasting ecological tasks.

Mice lacking both mixed-lineage kinase genes Mlk1 and Mlk2 retain a wild type phenotype.

The mitogen-activated protein kinase kinase kinases of the mixed-lineage kinase (MLK) family have been shown to activate the c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) pathway, and to regulate the other two principal MAPK cascades, p38 and extracellular signal-regulated kinase (ERK). Although there is growing evidence for their involvement in neuronal cell death leading to neurodegenerative disorders, little in vivo data is available for the members of this family of kinases. Here, we report that the inactivation of mouse Mlk1 and Mlk2 genes. Mlk1-/- and Mlk2-/- mice were found to be viable and healthy. Surprisingly, mice carrying the compound Mlk1/Mlk2 null mutations were also found to be viable, fertile and to have a normal life span. The nervous system, testis and kidney, the major sites of MLK1 and 2 expression, all appear normal, as do other organs where these kinases were found to be more weakly expressed. Surprisingly, developmental neuronal programmed cell death, another potential target for MLK family members, was also found to be unaffected. Our results suggest that there is extensive functional redundancy between MLK1/MLK2 and the other member of the family, MLK3, which is also not required for survival in mouse.

A tissue restricted role for the Xenopus Jun N-terminal kinase kinase kinase MLK2 in cement gland and pronephric tubule differentiation

The MLK family of mitogen activated protein kinase kinase kinases (MAPKKK) has been shown to activate Jun N-terminal kinase/stress-activated protein kinase 1 (JNK/SAPK1). However, little is known of the in vivo functions of the MLKs. We have identified a Xenopus laevis MLK that shows highest homology with mammalian MLK2 (62%) and, like MLK2, interacts preferentially with the Rho-family GTPase Rac. xMLK2 was expressed zygotically from late gastrula/early neurula. Surprisingly, this expression was restricted to the cement gland, the brain, and the pronephros. In the differentiating cement gland, xMLK2 expression correlated with cell elongation and the onset of a previously unobserved apoptotic phase, while in the pronephros, expression corresponded with the differentiation and opening of the nephric tubules. Overexpression of xMLK2 in COS7 cells led to a SEK1/MKK4 (MAPKK)-dependent hyperactivation of JNK in response to UV irradiation. xMLK2 was shown to be required for normal cement gland development and pronephric tubule formation using antisense inactivation and a dominant negative xMLK2. The data suggest a novel role for the MLKs as tissue-restricted mediators of signal transduction. They also suggest that tissue-specific responses to common extracellular signals may in part result from the programmed expression of MAPKKKs with differing specificities.

Role of p21-activated kinase in cell polarity and directional mesendoderm migration in the Xenopus gastrula†

The p21 activated kinases (Paks) are prominently involved in the regulation of cell motility. Using a kinase‐dead mutant of xPak1, we show that during Xenopus gastrulation, the kinase activity of Pak1 is required upstream of Cdc42 for the establishment of cell polarity in the migrating mesendoderm. Overactivation of Pak1 function by the expression of constitutively active xPak1 compromises the maintenance of cell polarity, by indirectly inhibiting RhoA function. Inhibition of cell polarization does not affect the migration of single mesendoderm cells. However, Pak1 inhibition interferes with the guidance of mesendoderm migration by directional cues residing in the extracellular matrix of the blastocoel roof, and with mesendoderm translocation in the embryo. Developmental Dynamics 238:1709–1726, 2009.

The p21-activated kinase Pak1 regulates induction and migration of the neural crest in Xenopus.

Pak1 is a member of the PAK family of serine/threonine kinases that are downstream effectors of Rac1 and Cdc42 small GTPases and are implicated in cytoskeleton reorganization. Early expression of Pak1 in Xenopus embryos is tissue restricted, suggesting a role in organogenesis and in cranial neural crest (CNC) cell migration. By observing CNC in vivo and after transplantation, we show that a dominant-negative (DN) Pak1 inhibits its migration. DN-Pak1 also specifically modified the expression of several NC markers. Twist expression was decreased and Snail1 expression posteriorized, but Snail2 (Slug), Sox9 and AP2 were unaffected. DN-Pak1 inhibition of CNC migration could be rescued with Snail1 but not with Twist, which, in fact, cooperated with DN-Pak1 in inhibiting migration. The data confirm that neither Snail1 nor Snail2 expression alone is sufficient for Xenopus CNC migration. Furthermore, they show that, in this tissue, Snail1 and Snail2 expression is not interdependent, nor are these factors subject to obligatory co-regulation, and that their expression depends on signal transduction. Our results also represent the first evidence that Pak1 links extracellular signals to the genetic cascade of transcription factors necessary for CNC specification.

Time Estimates of Internet Surfing and Video Gaming

Time estimation researchers have long been interested in the effects exerted by the time estimation paradigms, the task’s target duration and the nature of the task on the precision and variability of time estimates. Only a few studies though have focused on how these results can be applied to daily life tasks. Hence, the present study aims at exploring these effects with two different tasks: surfing the Internet and playing a video game. Results show that the time estimation paradigms, target duration and task effects normally observed in short and simple tasks can be extended to daily life tasks. Of relevance, the video gaming task was significantly underestimated compared to the Internet surfing task. These findings are discussed in the light of the current time estimation literature.

Sensitivity to time interval changes in speech and tone conditions

The main goal of the present experiment was to verify whether sensitivity to time interval changes in speech is greater than sensitivity to time interval changes between tones. The 12-syllable sentences were delivered in French (the main language of the participants) or in a foreign language (Slovenian) that was totally unfamiliar to the participants. Two types of sub-sequences were induced within the series of stimuli (sub-sequences in sentences or in tone sequences). Discrimination, as revealed by the Weber fraction in each condition, was much better in the tone conditions than in the speech conditions. Nevertheless, discrimination was excellent in all conditions: Weber fractions below 2% with tones and around 4.5% in the speech conditions. Moreover, the study revealed that familiarity with a particular language does not affect performance and that inducing internal sub-sequences within tone conditions, as opposed to using a series of equal intervals, does not lead to better discrimination. The fact that discrimination is better with tones than with sentences indicates that the extensive training provided by speech does not lead to higher sensitivity to time interval variations than simple tones do. Instead, it seems to indicate that the different acoustical variations in speech reduce the capability to discriminate time interval variations.

Perceptual asymmetries in the discrimination of brief auditory time intervals

This experiment was conducted to determine whether perceptual asymmetries would emerge in a task requiring the discrimination of two auditory time intervals. The first interval (standard) was presented binaurally and the other one (comparison) monaurally. The intervals were either filled (continuous sound) or empty (duration between two brief sounds). A total of 24 right-handed participants (12 women, 12 men) completed the four conditions (two Ear×two Structure). The results revealed that filled intervals were perceived as shorter when the monaural signal was presented to the left ear than when it was presented to the right ear, whereas there was no ear effect for empty intervals. Interval structure was not a significant factor when the monaural signals were delivered to the right ear, suggesting a right ear advantage in duration estimation. Finally, temporal sensitivity was better with empty than with filled intervals, but this effect was independent of the location of the monaural signals. The results are discussed with reference to potential effects of attention and the role of structural aspects underlying perceptual asymmetries.

Retrospective Temporal Judgment of the Period Dedicated to Recalling a Recent or an Old Emotional Memory

Sixty-one participants were asked (a) to recall a memory for a period lasting 15 minutes and (b), at the end of this period, to estimate retrospectively the duration of this period. They were assigned to one of four groups: the memory was either joyful or sad, and was recent (within the past two years) or old (when the participant was 7 to 10 years old). The most critical finding is the demonstration that the age of the recalled memory has an impact on the verbal estimation. More specifically, duration is underestimated in the old but not in the recent memory condition. Moreover, in this study, recalling a memory, old or recent, is shown to be an efficient way to generate a joyful or sad emotion. Finally, the results also indicate that there is a significant correlation between the uncertainty related to the duration estimated retrospectively and the score on the present-hedonistic scale of the Zimbardo Time Perspective Inventory.