Les bases neurales de la perception du temps et de la régulation temporelle de l'action

Synchronization, Attention and Transformation: Multidimensional Exploration of the Aesthetic Experience of Contemporary Dance Spectators

The co-presence of bodies in intersubjective situations can give rise to processes of kinesthetic empathy and physiological synchronization, especially in the context of dance: the body and attention of the spectators are oriented towards the dancers. In this study, we investigate the processes of "body-mind" resonance between a choreography and its spectators, and more specifically the lasting impact of this resonance post-performance. We then explore the relation between the observed effects and subjective measures of attention. The study focuses on the work of the French choreographer Myriam Gourfink, who develops a unique movement, based on the slower breathing of dancers: the breathing generates an extremely slow movement without rhythmic ruptures. Phenomenological studies of her work report changes in temporal perception and changes in bodily attentional states. We made use of two cognitive tasks in order to quantify this change in temporal perception: Spontaneous Motor Tempo (SMT) and Apparent Motion effect (AM) before and after a 40-min live performance. Subjective reports were collected at the end of the performance. Physiological data were recorded before and after the performance. We performed a control experiment with a choreography of a distinctly different quality of movement. Post-Gourfink performance, we observed a significant deceleration of SMT and a decrease in its variability, while AM was reported with longer temporal intervals. Neither of these effects was observed in the control condition. Furthermore, an increase in perception of AM was correlated with a slower breathing rate after the performance. Correlations with subjective reports suggest a link between changes in cognitive and physiological dynamics and the degree of absorption of the spectators in the performance. In addition, these changes were related to specific reported attentional dispositions that we interpret as a form of attentional resonance. The ensemble of the results suggests an expansion of the "specious present" that is related to the slowing of physiological rhythms, and an attentional resonance between spectators and the choreography. The intricate relation we observed between inter-personal resonance and temporal cognition, foregrounds the notion of shared present as a neurophenomenological construct.

The Sensitization of Aliphatic Epoxy Photopolymerization in Epoxy-Acrylate Interpenetrating Polymer Networks

The paper discuses the phenomenon of the sensitization of the aliphatic epoxy photopolymerization in the presence of acrylate oligomers while forming epoxy-acrylate interpenetrating polymer networks. The photopolymerization process was studied by IR spectroscopy and the properties of the final products – by the Gardner test, crosshatch adhesion test, and the pencil hardness test. The epoxy groups conversion, which is rather low in aliphatic epoxy polymers, was found to alter with the increase of acrylate compounds content. The materials synthesized on the base of interpenetrating polymer networks were shown to reveal fine properties and may have a potential application as coatings.

Duration discrimination in crossmodal sequences

Four duration-discrimination experiments were carried out to compare crossmodal and unimodal timing conditions. For all experiments, participants were presented with two sequences, each consisting of 1 or 4 time intervals (marked by 2 or 5 signals), and asked to indicate whether the interval(s) of the second sequence was (were) shorter or longer than the interval(s) of the first. Markers in the first and second sequences were, respectively, tones and flashes (experiment 1), flashes and tones (experiment 2), both flashes (experiment 3), and both tones (experiment 4). In all modality conditions, except when using only tones (experiment 4), increasing the number of repetitions of the variable interval reduced duration-discrimination thresholds, independently of whether the fixed interval was presented first or second within the sequence pair. Moreover, judgments about sequence timing were best for tones-tones sequence pairs, worst for flashes-flashes sequence pairs, and intermediate for crossmodal (flashes-tones or tones-flashes) sequences. Finally, presenting a fixed interval in the first sequence resulted in better discrimination than presenting a variable interval in the first sequence. Implications for theories of timing are discussed.

ERPs associated with visual duration discriminations in prefrontal and parietal cortex

An event-related potentials (ERP) study was undertaken to examine the role of prefrontal and parietal association cortices on selective attention and short-term memory functions in a duration discrimination task. Subjects performed better when discriminating the first stimulus relative to the second and not the reverse. Two contingent negative variations (CNV) were obtained for each stimulus duration at prefrontal regions, as well as two P300s at parietal regions. The CNV(S1) component recorded during the first stimulus (S1) appeared to be involved in selective attention at bilateral sites, while the P300(S1) component in the left hemisphere may be implicated in retaining it. The CNV(S2) wave, displayed during the second stimulus (S2), at bilateral sites and the right-sided P300(S2) wave seem to be implicated in working memory. The results indicate that recorded activity at prefrontal and parietal association cortices is tightly linked to task parameters and behavioral performances.