Balsdon, T. & Philiastides, M. (2024). Metacognitive control drives behavioural efficiency in dynamic sensory environments. Journal of Vision, 24(282). doi:10.1167/jov.24.10.282

Résumé :
Metacognitive evaluations of decision confidence reflect insight into the quality and quantity of evidence supporting our decisions. Signatures of confidence emerge during decision-making, implying confidence may be of functional importance to decision processes themselves. We formulated an extension of sequential sampling models of decision-making in which confidence is used online to actively moderate both the quality and quantity of evidence accumulated for perceptual decisions. The benefit of this model is that it can respond to dynamic changes in sensory evidence quality. We highlighted this feature by designing a dynamic sensory environment where evidence quality can be smoothly adapted within the timeframe of a single decision. Observers made fine-grained motion discrimination decisions about random dot motion displays. Dot directions were sampled from a circular gaussian distribution where the mean and variance of the distribution were adapted frame to frame to create trials with increasing or decreasing decision-evidence quality. Observers made fast, accurate decisions with early high-quality evidence but slowed down when faced with early low-quality evidence (though trials were intermixed). Our model with confidence control offers a far superior description of this pattern of behaviour than can be obtained from traditional models without online control mechanisms. Using multivariate decoding of electroencephalography (EEG), we uncovered EEG correlates of the model’s latent processes, and show stronger EEG-derived confidence control leads to faster, more accurate decisions within participants. These results support a neurobiologically plausible framework featuring confidence as an active control mechanism for driving efficient behaviour, that is, maximising precision given constraints of time and effort.

Leglaive, S., Fraticelli, M. , Borne, L. , Sadeghi, M. , Wisdom, S. , Pariente, M., R. Hershey, J. , Pressnitzer, D. & P. Barker, J. (2025). Objective and subjective evaluation of speech enhancement methods in the UDASE task of the 7th CHiME challenge. Computer Speech & Language, 89, 101685. doi:10.1016/j.csl.2024.101685

Résumé :
Supervised models for speech enhancement are trained using artificially generated mixtures of clean speech and noise signals. However, the synthetic training conditions may not accurately reflect real-world conditions encountered during testing. This discrepancy can result in poor performance when the test domain significantly differs from the synthetic training domain. To tackle this issue, the UDASE task of the 7th CHiME challenge aimed to leverage real-world noisy speech recordings from the test domain for unsupervised domain adaptation of speech enhancement models. Specifically, this test domain corresponds to the CHiME-5 dataset, characterized by real multi-speaker and conversational speech recordings made in noisy and reverberant domestic environments, for which ground-truth clean speech signals are not available. In this paper, we present the objective and subjective evaluations of the systems that were submitted to the CHiME-7 UDASE task, and we provide an analysis of the results. This analysis reveals a limited correlation between subjective ratings and several supervised nonintrusive performance metrics recently proposed for speech enhancement. Conversely, the results suggest that more traditional intrusive objective metrics can be used for in-domain performance evaluation using the reverberant LibriCHiME-5 dataset developed for the challenge. The subjective evaluation indicates that all systems successfully reduced the background noise, but always at the expense of increased distortion. Out of the four speech enhancement methods evaluated subjectively, only one demonstrated an improvement in overall quality compared to the unprocessed noisy speech, highlighting the difficulty of the task. The tools and audio material created for the CHiME-7 UDASE task are shared with the community.

Murez, M. & Strickland, B. (2024). Event completion: a test case for theories of reference in memory. Synthese, 204(78). doi:10.1007/s11229-024-04722-9

Résumé :
Although we encounter objects from a particular perspective, what we perceive and remember are typically whole objects. In ‘amodal completion’ our mind automatically fills in objects’ spatially occluded parts, and our memory then often discards information about the orientation from which the objects were perceived. An analogous phenomenon of ‘event completion’ has been demonstrated, which may be understood as the mind automatically filling in temporally occluded parts of events. Exemplifying typical experiments in this paradigm, Strickland and Keil (Strickland and Keil, Cognition 121:409–415, 2011) showed participants videos depicting a causal event (e.g., someone kicking a ball), which was edited so that a crucial part was missing (e.g., the moment of contact between foot and ball). Subjects were more likely to falsely remember having seen the moment of contact if (and only if) it was strongly implied by subsequent footage. We use this phenomenon of event completion as a test case for comparing different theories of reference in memory. We argue that event completion puts pressure on both pure causal and pure descriptive theories of reference, and favors more nuanced hybrids of causal and descriptive theories, which integrate insights from cognitive and epistemic approaches.

AGENDA

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Retrouvez les événements organisés par le DEC dans l'agenda du département.

Les séminaires et les conférences sont accessibles sur la chaîne youtube du département, le site des Savoirs de l'ENS, la chaîne youtube de l'école.

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L'Université PSL Fête la Science

Jusqu'au 14 octobre, l'Université PSL fête la science. Sciences expérimentales, sciences humaines et sociales, économie, droit… l’ensemble des domaines de recherche des 140 laboratoires de l’université sont au cœur d’une programmation riche adressée à un large public. Des plus jeunes élèves aux étudiant·es, en passant par les acteurs et actrices publics et les lycéen·nes, des actions de médiations scientifiques, des débats et conférences seront proposés sur les différents points du campus et au cœur de Paris.

Temps fort de cette programmation, le samedi 12 octobre, un village des sciences réunira les établissements PSL rue Erasme.

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