Auditory Ecology: Losing and restoring auditory contact with nature

Urban life increases the separation of humans with nature. However, green parks within cities and preserved nature areas still offer the opportunity to city-dwellers to experience nature, in particular their “soundscapes”, that is complex arrangements of biological and geophysical sounds. Several studies indicate that biodiversity, an important factor shaping soundscapes, determines the amount of well-being and so-called restorative effects associated with the auditory experience of natural soundscapes for humans. The population in developed countries ages and tends to develop hearing loss associated with ageing. Thus, for hearing-impaired (HI) persons visiting natural places or living in rural areas, quality of life and health should depend on accurate perception of soundscapes and the appropriate emotional response associated with this perceptual experience. 

The goal of this program is to characterize – for the first time – the impact of sensorineural hearing loss (SNHL) on auditory perception and emotional responses to natural and urban soundscapes, and the possibility to restore perception and emotional responses via hearing aids. This program aims to: (i) better understand the sensory mechanisms involved in auditory perception and emotional response to natural and urban soundscapes and their relationship; (ii) characterize and explain the effects of SNHL on perception and emotional response to these soundscapes; (iii) assess the extent to which alterations in soundscape perception and emotional responses can be restored back to normal via hearing aids. 

This will be achieved through a combination of psychophysical experiments and electrophysiological measurements in young and elderly normal-hearing and HI subjects, using a massive database of soundscapes recorded in nature reserves and urban sites. This work will be guided by predictions made using an information theoretic approach and a computational model of the human auditory system. 

This project involves  Christian Lorenzi (Laboratoire des Systèmes Perceptifs, DEC-ENS), Jérôme Sueur (Muséum National d'Histoire Naturelle), Diane Lazard and Luc Arnal (Institut de l'Audition, Institut Pasteur).
 

CAIAC - Neural computations of adaptive temporal integration in auditory cortex

People are remarkably skilled at perceiving and understanding complex sounds such as speech and music. Yet, the brain mechanisms that allow people to perceive complex sounds remain poorly understood. A key challenge faced by the brain is that sounds are organized across a vast range of timescales from milliseconds to seconds and minutes. To understand and perceive sounds, the brain must have mechanisms for flexibly integrating information across these diverse timescales. Understanding these mechanisms is critical to understanding how people understand speech, perceive music, and navigate the world using sound.

The proposed project investigates possible mechanisms the brain might use to flexibly integration information in sound. A key question we investigate is whether the brain can change the time window it integrates information over depending on the duration of sound “structures” such as words in speech. We test whether the brain can change its integration window over short and long timescales, and whether this flexibility depends on the types of sounds that one hears and their behavioral relevance. We study these questions using neural recordings from the auditory cortex, a new paradigm for studying temporal integration in the brain, and computational models derived from deep neural networks.

This project is led by Sam Normann (University of Rochester) and Yves Boubenec (Laboratoire des Systèmes Perceptifs, DEC-ENS).
 

CAREX (CES37) - Mechanisms of integration of cardiac interoceptive signals with exteroceptive signals

The last 10 years have uncovered a treasure-trove of experimental evidence that cardiac signals influence exteroceptive (somatosensory, visual) sensory processing, through both cardiac cycle effects (CCEs) and heartbeat evoked responses (HERs). The interplay between exteroception and interoception is sometimes competitive (i.e., attending the interoceptive or the exteroceptive stream), sometimes integrative (i.e., integration of interoception and exteroception contributes to conscious experience by relating external stimulus to the neural representation of the living organism). The rules governing integration vs. competition are not known. Besides, evidence has remained mostly correlational and the nature of the mechanisms involved is largely unknown. Here, we explore the mechanisms of influence of cardiac inputs on exteroceptive signals, in an integrated approach with an interplay of biologically plausible computational modelling and experiments in humans. The project will elaborate neural mechanisms for interoceptive modulation of somatosensory perception mediated by cardio-cortical coupling. Altogether, this project represents an important step to move the field forward, beyond the accumulation of correlative evidence. It also offers a first step toward a mechanistic understanding of the widely employed but under-specified notion of self-relevance, with potential long-term applications in psychiatry as well as in artificial intelligence and robotics.    
More precisely, in WP1, we will construct a biophysically-based cardio-cortical model, where a cortical mini-column, with ongoing and sensory-evoked activity, is modulated by a dynamic cardiac oscillator (which produces synthetic realistic electrocardiograms). Using this model, we explicitly delineate the mechanisms of this ascending influence. We will validate the model by optimizing the parameters of coupling and the dynamics of the cortical and cardiac modules to fit existing electrocardiogram and intracranial data. In parallel (WP2), we will obtain further EEG data in female and male participants probing the interaction between cardiac and tactile processing with a critical manipulation of self-relevance, a factor that might govern the balance between cardio-tactile competition vs. cardio-tactile integration. We posit that self-relevance is a combination of exteroceptive stimulus properties and internal state. Stimulus-induced self-relevance is operationalized here as a tactile stimulus delivered with a near sound (more self-relevant), or with a far sound (less self-relevant), and fluctuations in self-related internal state are indexed by source-localized HERs. In WP3, we will expand the model developed in WP1 to confront the data from WP2 to test several mechanistic hypotheses on the interactions between intero- and exetero-ceptive stimuli.

The project involves Catherine Tallon-Baudry (Subjectivity, brain and viscera team, Laboratoire de Neurosciences cognitive et Computationnelles, DEC-ENS) and Boris Gutkin (Mathematics of neural circuits team, Laboratoire de Neurosciences cognitive et Computationnelles, DEC-ENS).
 

CAT - Collective affect in theatre
Study of the emergence of collective emotional dynamics during theatrical performances.

Though sharing emotions at theatre is assumed to be a very common experience, there is to date little scientific evidence supporting this assumption. By pooling together expertise from social cognitivists and philosophers, the present project will conduct the first systematic investigation of the emergence of collective emotional dynamics during theatre performances. Our research hypotheses are that (H1) the specific nature of the theatrical emotional experience relies on synchronized patterns of autonomic activity and converging subjective emotional experiences within the audience and between the audience and actors, and that (H2) these shared emotions within the audience and between the audience and actors play a role in our appreciation of the theatrical performance. We propose two Work Packages, respectively tackling the interpersonal emotional dynamics in theatre audiences (WP1) and the reciprocal actors-audience relations (WP2). In both WPs, we will conduct experimental studies in naturalistic settings, recruiting large groups of participants to attend short plays performed by professional actors, while manipulating the type of theatrical performance and the composition of the audience. Importantly, we will replicate our findings to performances programmed in two national theatres (Le Quai d’Angers, Nanterre-Amandiers).

This project is led by Julie Grèzes (Social cognition : from brain to society team, Laboratoire de Neurosciences Cognitives et Computationnelles, DEC-ENS) in collaboration with Jérôme Pelletier (Institut Jean Nicod, DEC, ENS).

ComCogMean - Communicative efficiency , cognitive constraints and lexical meaning

Languages show certain universal tendencies in the way they choose to lexicalize meanings. These tendencies have often been argued to reflect the fact that, across cultural evolution, languages tend to be optimized for efficient communication. However, they  can also be the result of various cognitive pressures that exist independently of communication, or follow from how word meaning is learnt, quite independently of communicative efficiency.

In this project, we will focus on the role played by meaning in shaping the form of the lexicon (such as word length or the lexicalization of certain logical words). We will study the respective roles of non-communicative cognitive constraints and communicative efficiency in explaining word-meaning mappings, by means of three case-studies

P1. Meaning competition, which may explain that languages show limited synonymy, and that there is a ‘mutual exclusivity’ effect in word learning (new words are assigned to novel meanings)

P2. Meaning frequency. Zipf's law of abbreviation relates word frequencies and word length. We argue that frequencies in the world cannot be ignored in this relation.

P3. Meaning complexity. Some words never occur across word languages.  Focusing on logical words such as connectives and quantifiers, we explore how the complexity of a concept interacts with communicative pressures to let it occur or not as a lexical item. 

We will pursue this program by developing explicit formal models, using the tools of probabilistic pragmatics (esp. the Rational Speech Act model) and Bayesian modeling, whose predictions will be tested against data from corpora and experimental data.

This project involves three researchers frop our department, Benjamin Spector (LINGUAE and COLOR, Institut Jean Nicod, DEC-ENS), Olivier Morin (Cognition Sociale team, Institut Jean Nicod, DEC-ENS), Emmanuel Chemla (Language and Its acquisition team, Laboratoire de Sciences Cognitives et Psycholinguistique, LINGUAE team, Institut Jean Nicod, DEC-ENS) and Mora Maldonado (Laboratoire de Linguistique, Nantes).

The THRESHOLD of desperation: Consequences for individuals and society 

Theories of human decision-making assume that people make choices that seem likely to maximize their utility. When decisions have material implications this is often taken to mean that they should prefer the option that maximizes their expected financial return. However, people very often deviate from doing so. Usually they are risk averse: they make choices that reduce their expected return, whilst avoiding the prospect of losses (for example, they buy insurance). On the other hand, people are sometimes risk-prone: they make choices that reduce their expected utility but carry a small chance of a large gain (for example, they buy lottery tickets). Risk-proneness has important societal implications. For example, the persistence of acquisitive crime in the face of stiff penalties could be explained by some people being risk-prone under certain circumstances. How can we explain the observed mixture of risk-aversion and occasional risk-proneness, and what implications does this have for improving societal wellbeing?

The central hypothesis of this project is that, in many situations, what people care about most is maintaining a minimal resource requirement. We can model this by mapping utility to resources using a function with a desperation threshold. A utility function with a desperation threshold has three features: a level of resources at which utility changes very abruptly (the threshold itself); a relatively shallow slope above the threshold; and a zone below the threshold where the slope is largely flat. Given this shape, the rational agent will be risk averse when their resources are above the threshold, especially just above it; and highly risk prone when resources are currently or imminently below the threshold. Above the threshold, their main priority is not falling down, whereas below the threshold, they have nothing left to lose, and it’s worth trying anything at all that offers a possible route back up.

We have formally modelled the rational-choice implications of the existence of a desperation threshold, with interesting implications for the effects of poverty and inequality on behaviour (de Courson et al., 2023; de Courson & Nettle, 2021). However, we have not yet empirically tested the assumptions, predictions or consequences of those models. This is the goal of the present project. First, the assumptions: do people actually experience something like the pattern in figure 1 as their resources change, or do they believe that they will do so (work package [WP] 1)? Second, do people behave with the characteristic combination of risk-proneness below the threshold and risk-aversion above that the theory predicts (WP2)? Third, what implications does this have for society as a whole and for policy (WP3)? For example, what should be the implications for outcomes like crime rates and mental health when inequality increases, or when policies like Universal Basic Income, which guarantees individuals a level of resources below which they cannot fall, are introduced? 

We will answer these questions with a unique combination of: secondary data analysis; quantitative and qualitative community research; behavioural experiments; and population micro-simulation. The project leader is experienced in the relevant methods, and additionally has assembled a team of advisors and collaborators that includes psychologists, evolutionary biologists, and political scientists. 

Understanding desperation thresholds and their effects on individual behaviour will make a novel contribution to decision-making psychology, but also provide micro-foundations for social theory, and allow us to model the psychological and behavioural consequences of public policies in a way that will have real-world impact.

This project is led by Daniel Nettle (Institut Jean Nicod, DEC-ENS).  

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