Towards a scientific concept of free will as a biological trait: spontaneous actions and decision-making in invertebrates

Possibilities of Free Will in Different Physical, Social, and Technological Worlds: An Introduction to a Thematic Issue

In this introduction to a thematic issue dealing with free will, some possibilities of free will in different physical, social, and technological worlds, as well as discussions of the possibilities are considered. What are the possibilities and limitations of free will in various other worlds differing from our world? What are the possibilities and limitations of free will in different species, both in our world and in other hypothetical worlds, including future species, naturally evolving, and artificially modified? What are the possibilities and limitations of free will related to the development of AI? How can the diversity of free will levels in an agent be related to possible levels (depth) of its self-knowledge? What can agents differing in levels of self-knowledge know and think about the issue of free will? How do different societies (social worlds) support and inhibit different manifestations of free will in different areas? What is the role of hard neurodeterminism and "mindless neuroscience" in general neuroscience? What are ethical aspects of the questions, including the initial one: "If a neuroscientist denies free will, how can they write a text of voluntary informed consent and propose to sign it?".

The place of Free Will: the freedom of the prisoner

Debates about the concept of Free Will date back to ancient times. About 40 years ago, Benjamin Libet designed an experiment showing that the conscious intention to move is preceded by a specific pattern of brain activation. His finding suggested that unconscious processes determine our decisions. Libet-style experiments have continued to dominate the debate about Free Will, pushing some authors to argue that the existence of Free Will is a mere illusion. We believe that this dispute is because we often measure Free Will using arbitrary human decisions rather than deliberate actions. After reviewing the definition of Free Will and the related literature, we conclude that the scientific evidence does not disprove the existence of Free Will. However, our will encounters several constraints and limitations that should be considered when evaluating our deeds' personal responsibility.

A systematic approach to brain dynamics: cognitive evolution theory of consciousness

The brain integrates volition, cognition, and consciousness seamlessly over three hierarchical (scale-dependent) levels of neural activity for their emergence: a causal or 'hard' level, a computational (unconscious) or 'soft' level, and a phenomenal (conscious) or 'psyche' level respectively. The cognitive evolution theory (CET) is based on three general prerequisites: physicalism, dynamism, and emergentism, which entail five consequences about the nature of consciousness: discreteness, passivity, uniqueness, integrity, and graduation. CET starts from the assumption that brains should have primarily evolved as volitional subsystems of organisms, not as prediction machines. This emphasizes the dynamical nature of consciousness in terms of critical dynamics to account for metastability, avalanches, and self-organized criticality of brain processes, then coupling it with volition and cognition in a framework unified over the levels. Consciousness emerges near critical points, and unfolds as a discrete stream of momentary states, each volitionally driven from oldest subcortical arousal systems. The stream is the brain's way of making a difference via predictive (Bayesian) processing. Its objective observables could be complexity measures reflecting levels of consciousness and its dynamical coherency to reveal how much knowledge (information gain) the brain acquires over the stream. CET also proposes a quantitative classification of both disorders of consciousness and mental disorders within that unified framework.

From the origins to the stream of consciousness and its neural correlates

There are now dozens of very different theories of consciousness, each somehow contributing to our understanding of its nature. The science of consciousness needs therefore not new theories but a general framework integrating insights from those, yet not making it a still-born "Frankenstein" theory. First, the framework must operate explicitly on the stream of consciousness, not on its static description. Second, this dynamical account must also be put on the evolutionary timeline to explain the origins of consciousness. The Cognitive Evolution Theory (CET), outlined here, proposes such a framework. This starts with the assumption that brains have primarily evolved as volitional subsystems of organisms, inherited from primitive (fast and random) reflexes of simplest neural networks, only then resembling error-minimizing prediction machines. CET adopts the tools of critical dynamics to account for metastability, scale-free avalanches, and self-organization which are all intrinsic to brain dynamics. This formalizes the stream of consciousness as a discrete (transitive, irreflexive) chain of momentary states derived from critical brain dynamics at points of phase transitions and mapped then onto a state space as neural correlates of a particular conscious state. The continuous/discrete dichotomy appears naturally between the brain dynamics at the causal level and conscious states at the phenomenal level, each volitionally triggered from arousal centers of the brainstem and cognitively modulated by thalamocortical systems. Their objective observables can be entropy-based complexity measures, reflecting the transient level or quantity of consciousness at that moment.

Choices by organisms: on the role of freedom in behaviour and evolution

Neo-Darwinian biology has demonstrated that it is possible to construct a theory of life that excludes the role of organisms’ free choice. In a richer theory, the latter as a possibility needs to be taken into account. For that purpose, it is necessary to introduce the biological concept of choice, analyse its structure and roles, and consider some implications for biological theory. It is argued here that the conditions for free choice emerge together with umwelt—the space of synchronous options. Basically, choice does not require purpose. This leads to the conclusion that freedom is an attribute of life.

Choice Hygiene for "Consumer Neuroscientists"? Ethical Considerations and Proposals for Future Endeavours

Is the use of psychological and neuroscientific methods for neuromarketing research always aligned with the principles of ethical research practice? Some neuromarketing endeavours have passed from informing consumers about available options, to helping to market as many products to consumers as possible. Needs are being engineered, using knowledge about the human brain to increase consumption further, regardless of individual, societal and environmental needs and capacities. In principle, the ground ethical principle of any scientist is to further individual, societal and environmental health and well-being with their work. If their findings can be used for the opposite, this must be part of the scientist's considerations before engaging in such research and to make sure that the risks for misuse are minimised. Against this backdrop, we provide a series of real-life examples and a non-exhaustive literature review, to discuss in what way some practices in the neuromarketing domain may violate the Helsinki Declaration of Experimentation with Human Subjects. This declaration was set out to regulate biomedical research, but has since its inception been applied internationally also to behavioural and social research. We illustrate, point by point, how these ground ethical principles should be applied also to the neuromarketing domain. Indisputably, the growth in consumption is required due to current prevalent economical models. Thus, in the final part of the paper, we discuss how alternative models may be promotable to a larger public, aided by more ethical marketing endeavours, based on neuroscientific discoveries about the human brain. We propose this as a philosophical question, a point of discussion for the future, to make neuromarketing as a discipline, fit for the future, respecting the ethical implications of this research.

Male song stability shows cross-year repeatability but does not affect reproductive success in a wild passerine bird

Predictable behaviour (or "behavioural stability") might be favoured in certain ecological contexts, e.g. when representing a quality signal. Costs associated with producing stable phenotypes imply selection should favour plasticity in stability when beneficial. Repeatable among-individual differences in degree of stability are simultaneously expected if individuals differ in ability to pay these costs, or in how they resolve cost-benefit trade-offs. Bird song represents a prime example, where stability may be costly yet beneficial when stable singing is a quality signal favoured by sexual selection. Assuming energetic costs, ecological variation (e.g. in food availability) should result in both within- and among-individual variation in stability. If song stability represents a quality signal, we expect directional selection favouring stable singers. For a three-year period, we monitored 12 nest box plots of great tits Parus major during breeding. We recorded male songs during simulated territory intrusions, twice during their mate's laying stage, and twice during incubation. Each preceding winter, we manipulated food availability. Assuming that stability is costly, we expected food-supplemented males to sing more stable songs. We also expected males to sing more stable songs early in the breeding season (when paternity is not decided), and stable singers to have increased reproductive success. We found strong support for plasticity in stability for two key song characteristics: minimum frequency and phrase length. Males were plastic because they became more stable over the season, contrary to expectations. Food-supplementation did not affect body condition but increased stability in minimum frequency. This treatment effect occurred only in one year, implying that food supplementation affected stability only in interaction with (unknown) year-specific ecological factors. We found no support for directional, correlational, or fluctuating selection on the stability in minimum frequency (i.e., the song trait whose stability exhibited cross-year repeatability): stable singers did not have higher reproductive success. Our findings imply that stability in minimum frequency is not a fitness quality indicator unless males enjoy fitness benefits via pathways not studied here. Future studies should thus address the mechanisms shaping and maintaining individual repeatability of song stability in the wild.

From Biological Synapses to “Intelligent” Robots

This selective review explores biologically inspired learning as a model for intelligent robot control and sensing technology on the basis of specific examples. Hebbian synaptic learning is discussed as a functionally relevant model for machine learning and intelligence, as explained on the basis of examples from the highly plastic biological neural networks of invertebrates and vertebrates. Its potential for adaptive learning and control without supervision, the generation of functional complexity, and control architectures based on self-organization is brought forward. Learning without prior knowledge based on excitatory and inhibitory neural mechanisms accounts for the process through which survival-relevant or task-relevant representations are either reinforced or suppressed. The basic mechanisms of unsupervised biological learning drive synaptic plasticity and adaptation for behavioral success in living brains with different levels of complexity. The insights collected here point toward the Hebbian model as a choice solution for “intelligent” robotics and sensor systems.

Some Methodological Issues in Neuroethics: The Case of Responsibility and Psychopathy

There are some distinct methodological challenges, and possible pitfalls, for neuroethics when it evaluates neuroscientific results and links them to issues such as moral or legal responsibility. Some problems emerge in determining the requirements for responsibility. We will show how philosophical proposals in this area need to interact with legal doctrine and practice. Problems can occur when inferring normative implications from neuroscientific results. Other problems arise when it is not recognized that data about brain anatomy or physiology are relevant to the ascription of responsibility only when they are significantly correlated with the psychological capacities contemplated by the legal formulations of responsibility. We will demonstrate this by considering two significant cases concerning psychopathy. Some paradigms that aim at measuring higher-order capacities, such as moral understanding, have limited validity. More robust paradigms for the study of learning in restricted controlled conditions, on the other hand, have limited ecological validity across individuals and context to be of any use for the law.

Imitation and interindividual differences: Belief in free will is not related to automatic imitation

It is well known that individuals have the tendency to automatically imitate each other and that such imitative behavior is fostered by perceiving intentions in others' actions. That is, past research has shown that perceiving an action as internally driven enhances the shared representation of observed and executed actions increasing automatic imitation. An interpersonal factor that increases the perception that a behavior is internally driven is belief in free will. Consequently, we hypothesized that the more individuals believe in free will, the more they automatically imitate others. To test this prediction, we conducted two high-powered (total N = 642) and preregistered studies in which we assessed automatic imitation with the imitation-inhibition task. Contrary to our predictions, belief in free will did not correlate with automatic imitation. This finding contributes to current findings challenging the assumption that automatic imitation is modulated by interindividual differences. Further theoretical implications are discussed.

Collective action or individual choice: Spontaneity and individuality contribute to decision-making in Drosophila

Our own unique character traits make our behavior consistent and define our individuality. Yet, this consistency does not entail that we behave repetitively like machines. Like humans, animals also combine personality traits with spontaneity to produce adaptive behavior: consistent, but not fully predictable. Here, we study an iconically rigid behavioral trait, insect phototaxis, that nevertheless also contains both components of individuality and spontaneity. In a light/dark T-maze, approximately 70% of a group of Drosophila fruit flies choose the bright arm of the T-Maze, while the remaining 30% walk into the dark. Taking the photopositive and the photonegative subgroups and re-testing them reveals the spontaneous component: a similar 70–30 distribution emerges in each of the two subgroups. Increasing the number of choices to ten choices, reveals the individuality component: flies with an extremely negative series of first choices were more likely to show photonegative behavior in subsequent choices and vice versa. General behavioral traits, independent of light/dark preference, contributed to the development of this individuality. The interaction of individuality and spontaneity together explains why group averages, even for such seemingly stereotypical behaviors, are poor predictors of individual choices.

Computational animal welfare: towards cognitive architecture models of animal sentience, emotion and wellbeing

To understand animal wellbeing, we need to consider subjective phenomena and sentience. This is challenging, since these properties are private and cannot be observed directly. Certain motivations, emotions and related internal states can be inferred in animals through experiments that involve choice, learning, generalization and decision-making. Yet, even though there is significant progress in elucidating the neurobiology of human consciousness, animal consciousness is still a mystery. We propose that computational animal welfare science emerges at the intersection of animal behaviour, welfare and computational cognition. By using ideas from cognitive science, we develop a functional and generic definition of subjective phenomena as any process or state of the organism that exists from the first-person perspective and cannot be isolated from the animal subject. We then outline a general cognitive architecture to model simple forms of subjective processes and sentience. This includes evolutionary adaptation which contains top-down attention modulation, predictive processing and subjective simulation by re-entrant (recursive) computations. Thereafter, we show how this approach uses major characteristics of the subjective experience: elementary self-awareness, global workspace and qualia with unity and continuity. This provides a formal framework for process-based modelling of animal needs, subjective states, sentience and wellbeing.

The thalamus integrates the macrosystems of the brain to facilitate complex, adaptive brain network dynamics

The human brain is a complex, adaptive system comprised of billions of cells with trillions of connections. The interactions between the elements of the system oppose this seemingly limitless capacity by constraining the system's dynamic repertoire, enforcing distributed neural states that balance integration and differentiation. How this trade-off is mediated by the brain, and how the emergent, distributed neural patterns give rise to cognition and awareness, remains poorly understood. Here, I argue that the thalamus is well-placed to arbitrate the interactions between distributed neural assemblies in the cerebral cortex. Different classes of thalamocortical connections are hypothesized to promote either feed-forward or feedback processing modes in the cerebral cortex. This activity can be conceptualized as emerging dynamically from an evolving attractor landscape, with the relative engagement of distinct distributed circuits providing differing constraints over the manner in which brain state trajectories change over time. In addition, inputs to the distinct thalamic populations from the cerebellum and basal ganglia, respectively, are proposed to differentially shape the attractor landscape, and hence, the temporal evolution of cortical assemblies. The coordinated engagement of these neural macrosystems is then shown to share key characteristics with prominent models of cognition, attention and conscious awareness. In this way, the crucial role of the thalamus in mediating the distributed, multi-scale network organization of the central nervous system can be related to higher brain function.

The Readiness Potential reflects planning-based expectation, not uncertainty, in the timing of action

Actions are guided by a combination of external cues, internal intentions, and stored knowledge. Self-initiated voluntary actions, produced without immediate external cues, may be preceded by a slow EEG Readiness Potential (RP) that progressively increases prior to action. The cognitive significance of this neural event is controversial. Some accounts link the RP to the fact that timing of voluntary actions is generated endogenously, without external constraints. Others link it to the unique role of a planning process, and therefore of temporal expectation, in voluntary actions. In many previous experiments, actions are unconstrained by external cues, but also potentially involve preplanning and anticipation. To separate these factors, we developed a reinforcement learning paradigm where participants learned, through trial and error, the optimal time to act. If the RP reflects freedom from external constraint, its amplitude should be greater early in learning, when participants do not yet know when to act. Conversely, if the RP reflects planning, it should be greater later on, when participants have learned, and plan in advance, the time of action. We found that RP amplitudes grew with learning, suggesting that this neural activity reflects planning and anticipation for the forthcoming action, rather than freedom from external constraint.

Intra-Individual Behavioural Variability: A Trait under Genetic Control

When individuals are measured more than once in the same context they do not behave in exactly the same way each time. The degree of predictability differs between individuals, with some individuals showing low levels of variation around their behavioural mean while others show high levels of variation. This intra-individual variability in behaviour has received much less attention than between-individual variability in behaviour, and very little is known about the underlying mechanisms that affect this potentially large but understudied component of behavioural variation. In this study, we combine standardized behavioural tests in a chicken intercross to estimate intra-individual behavioural variability with a large-scale genomics analysis to identify genes affecting intra-individual behavioural variability in an avian population. We used a variety of different anxiety-related behavioural phenotypes for this purpose. Our study shows that intra-individual variability in behaviour has a direct genetic basis that is largely unique compared to the genetic architecture for the standard behavioural measures they are based on (at least in the detected quantitative trait locus). We identify six suggestive candidate genes that may underpin differences in intra-individual behavioural variability, with several of these candidates having previously been linked to behaviour and mental health. These findings demonstrate that intra-individual variability in behaviour appears to be a heritable trait in and of itself on which evolution can act.

Functional advantages of Lévy walks emerging near a critical point

A special class of random walks, so-called Lévy walks, has been observed in a variety of organisms ranging from cells, insects, fishes, and birds to mammals, including humans. Although their prevalence is considered to be a consequence of natural selection for higher search efficiency, some findings suggest that Lévy walks might also be epiphenomena that arise from interactions with the environment. Therefore, why they are common in biological movements remains an open question. Based on some evidence that Lévy walks are spontaneously generated in the brain and the fact that power-law distributions in Lévy walks can emerge at a critical point, we hypothesized that the advantages of Lévy walks might be enhanced by criticality. However, the functional advantages of Lévy walks are poorly understood. Here, we modeled nonlinear systems for the generation of locomotion and showed that Lévy walks emerging near a critical point had optimal dynamic ranges for coding information. This discovery suggested that Lévy walks could change movement trajectories based on the magnitude of environmental stimuli. We then showed that the high flexibility of Lévy walks enabled switching exploitation/exploration based on the nature of external cues. Finally, we analyzed the movement trajectories of freely moving Drosophila larvae and showed empirically that the Lévy walks may emerge near a critical point and have large dynamic range and high flexibility. Our results suggest that the commonly observed Lévy walks emerge near a critical point and could be explained on the basis of these functional advantages.

Post-contact immobility and half-lives that save lives

A wide variety of animals become completely immobile after initial contact with a potential predator. This behaviour is considered to be a last-ditch escape strategy. Here, we test the hypothesis that such immobility should have an extremely unpredictable duration. We find that it spans more than three orders of magnitude in antlion larvae. We also analyse the second period of immobility that follows the first bout of immobility, and consider the distributions of both first and second immobility periods within the context of the intermittence that characterizes the movement of most organisms. Both immobility durations were fitted best by exponential distributions. Therefore, both were characterized by high variability and hence, unpredictability. The immobility half-life, its mean duration and standard deviation were greater for the first than the second immobility. Furthermore, individual consistency was weak or absent in repeated measures of the first immobility and between the first and second immobilities. Our quantitative approach can be replicated across taxa and would help link an understanding of immobility after an initial predator contact in both vertebrates and invertebrates. To facilitate this, we contend that the terminology should be simplified, and we advocate the use of the term post-contact immobility (PCI).

Insights from the study of complex systems for the ecology and evolution of animal populations

Populations of animals comprise many individuals, interacting in multiple contexts, and displaying heterogeneous behaviors. The interactions among individuals can often create population dynamics that are fundamentally deterministic yet display unpredictable dynamics. Animal populations can, therefore, be thought of as complex systems. Complex systems display properties such as nonlinearity and uncertainty and show emergent properties that cannot be explained by a simple sum of the interacting components. Any system where entities compete, cooperate, or interfere with one another may possess such qualities, making animal populations similar on many levels to complex systems. Some fields are already embracing elements of complexity to help understand the dynamics of animal populations, but a wider application of complexity science in ecology and evolution has not occurred. We review here how approaches from complexity science could be applied to the study of the interactions and behavior of individuals within animal populations and highlight how this way of thinking can enhance our understanding of population dynamics in animals. We focus on 8 key characteristics of complex systems: hierarchy, heterogeneity, self-organization, openness, adaptation, memory, nonlinearity, and uncertainty. For each topic we discuss how concepts from complexity theory are applicable in animal populations and emphasize the unique insights they provide. We finish by outlining outstanding questions or predictions to be evaluated using behavioral and ecological data. Our goal throughout this article is to familiarize animal ecologists with the basics of each of these concepts and highlight the new perspectives that they could bring to variety of subfields.

Maternal diet affects juvenile Carpetan rock lizard performance and personality

Differences in both stable and labile state variables are known to affect the emergence and maintenance of consistent interindividual behavioral variation (animal personality or behavioral syndrome), especially when experienced early in life. Variation in environmental conditions experienced by gestating mothers (viz. nongenetic maternal effects) is known to have significant impact on offspring condition and behavior; yet, their effect on behavioral consistency is not clear. Here, by applying an orthogonal experimental design, we aimed to study whether increased vitamin D3 content in maternal diet during gestation (vitamin-supplemented vs. vitamin control treatments) combined with corticosterone treatment (corticosterone-treated vs. corticosterone control treatments) applied on freshly hatched juveniles had an effect on individual state and behavioral consistency of juvenile Carpetan rock lizards (Iberolacerta cyreni). We tested the effect of our treatments on (a) climbing speed and the following levels of behavioral variation, (b) strength of animal personality (behavioral repeatability), (c) behavioral type (individual mean behavior), and (d) behavioral predictability (within-individual behavioral variation unrelated to environmental change). We found higher locomotor performance of juveniles from the vitamin-supplemented group (42.4% increase), irrespective of corticosterone treatment. While activity personality was present in all treatments, shelter use personality was present only in the vitamin-supplemented × corticosterone-treated treatment and risk-taking personality was present in corticosterone control treatments. Contrary to our expectations, behavioral type was not affected by our treatments, indicating that individual quality can affect behavioral strategies without affecting group-level mean behavior. Behavioral predictability decreased in individuals with low climbing speed, which could be interpreted as a form of antipredator strategy. Our results clearly demonstrate that maternal diet and corticosterone treatment have the potential to induce or hamper between-individual variation in different components of boldness, often in interactions.

Optimal foraging and the information theory of gambling

At a macroscopic level, part of the ant colony life cycle is simple: a colony collects resources; these resources are converted into more ants, and these ants in turn collect more resources. Because more ants collect more resources, this is a multiplicative process, and the expected logarithm of the amount of resources determines how successful the colony will be in the long run. Over 60 years ago, Kelly showed, using information theoretic techniques, that the rate of growth of resources for such a situation is optimized by a strategy of betting in proportion to the probability of pay-off. Thus, in the case of ants, the fraction of the colony foraging at a given location should be proportional to the probability that resources will be found there, a result widely applied in the mathematics of gambling. This theoretical optimum leads to predictions as to which collective ant movement strategies might have evolved. Here, we show how colony-level optimal foraging behaviour can be achieved by mapping movement to Markov chain Monte Carlo (MCMC) methods, specifically Hamiltonian Monte Carlo (HMC). This can be done by the ants following a (noisy) local measurement of the (logarithm of) resource probability gradient (possibly supplemented with momentum, i.e. a propensity to move in the same direction). This maps the problem of foraging (via the information theory of gambling, stochastic dynamics and techniques employed within Bayesian statistics to efficiently sample from probability distributions) to simple models of ant foraging behaviour. This identification has broad applicability, facilitates the application of information theory approaches to understand movement ecology and unifies insights from existing biomechanical, cognitive, random and optimality movement paradigms. At the cost of requiring ants to obtain (noisy) resource gradient information, we show that this model is both efficient and matches a number of characteristics of real ant exploration.

Neurocognitive free will

Free will is an apparent paradox because it requires a historical identity to escape its history in a self-guided fashion. Philosophers have itemized design features necessary for this escape, scaling from action to agency and vice versa. These can be organized into a coherent framework that neurocognitive capacities provide and that form a basis for neurocognitive free will. These capacities include (1) adaptive access to unpredictability, (2) tuning of this unpredictability in the service of hierarchical goal structures, (3) goal-directed deliberation via search over internal cognitive representations, and (4) a role for conscious construction of the self in the generation and choice of alternatives. This frames free will as a process of generative self-construction, by which an iterative search process samples from experience in an adaptively exploratory fashion, allowing the agent to explore itself in the construction of alternative futures. This provides an explanation of how effortful conscious control modulates adaptive access to unpredictability and resolves one of free will's key conceptual problems: how randomness is used in the service of the will. The implications provide a contemporary neurocognitive grounding to compatibilist and libertarian positions on free will, and demonstrate how neurocognitive understanding can contribute to this debate by presenting free will as an interaction between our freedom and our will.

Two Distinctions That Help to Chart the Interplay Between Conscious and Unconscious Volition

Research initiated by Benjamin Libet suggests that short-term conscious intentions are not the onsets of bodily actions. However, other research, particularly on longer-term intentions, seems to show that at least some conscious intentions are effective. This leads to the idea that volition is a complex interplay between conscious and unconscious processes. The nature and structure of this interplay is mostly uncharted territory. In this article, I will highlight two currently neglected distinctions that will help to chart the territory. The first distinction is between intentions we become conscious of (passive) and consciously formed intentions (active). The second is Fred Dretske’s distinction between structuring and triggering causes. I will introduce both distinctions by discussing how they tie in with and strengthen recent criticism of free selection paradigms and support the idea that consciously self-initiated action issues from processes of conscious deliberation and/or information integration. I will argue that consciously self-initiated action typically involves consciously formed intentions that are the structuring causes of our actions. This notion of conscious intentional action allows us to identify at least four stages in which unconscious processes co-determine our actions—without undermining their self-initiated character.

The influence of environmental gradients on individual behaviour: Individual plasticity is consistent across risk and temperature gradients

The expression of individual behaviour as a function of environmental variation (behavioural plasticity) is recognized as a means for animals to modify their phenotypes in response to changing conditions. Plasticity has been studied extensively in recent years, leading to an accumulation of evidence for behavioural plasticity within natural populations. Despite the recent attention given to studying individual variation in behavioural plasticity, there is still a lack of consensus regarding its causes and constraints. One pressing question related to this is whether individual plasticity carries over across temporal and environmental gradients. That is, are some individuals more plastic (responsive) than others in general? Here, we examined the influence of temporal and environmental gradients on individual behavioural responses in a marine gastropod, Littoraria irrorata. We measured individual boldness repeatedly over time and in response to tidal cycle (high vs. low, an index of risk) and daily temperature fluctuations (known to affect metabolism), in a controlled field experiment. On average, boldness increased from high to low tide and with increasing temperature but decreased marginally over time. Individuals also differed in their responses to variation in tide and temperature, but not over time. Those which were relatively bold at high tide (when predation risk is greater) were similarly bold at low tide, whereas shy individuals became much more "bold" at low tide. Most notably, individuals that were more responsive to tide (and thus risk) were also more responsive to temperature changes, indicating that plasticity was correlated across contexts (r = 0.57) and that bolder individuals were least plastic overall. This study provides a rare and possibly first example of consistency of individual behavioural plasticity across contexts, suggesting underlying physiology as a common mechanism, and raises the possibility of correlational selection on plasticity.

Laypersons' Beliefs and Intuitions About Free Will and Determinism: New Insights Linking the Social Psychology and Experimental Philosophy Paradigms

We linked between the social psychology and experimental philosophy paradigms for the study of folk intuitions and beliefs regarding the concept of free will to answer three questions: (1) What intuitions do people have about free will and determinism? (2) Do free will beliefs predict differences in free will and determinism intuitions? and (3) Is there more to free will and determinism than experiencing certainty or uncertainty about the nature of the universe? Overall, laypersons viewed the universe as allowing for human indeterminism, and they did so with certainty. Examining intuitions of prosociality, future orientation, learning, meaningfulness, human uniqueness, and well-being, ratings were highest in the indeterministic universe condition and lowest in the deterministic universe condition, both significantly different from the uncertain universe condition. Participants' free will beliefs had only weak impact on realism, happiness, and learning intuitions but did not reverse the general intuition favoring indeterminism and showed no impact on other intuitions.

A Stochastic Process Model for Free Agency under Indeterminism

The aim of this paper is to establish that free agency, which is a capacity of many animals including human beings, is compatible with indeterminism: an indeterministic world allows for the existence of free agency. The question of the compatibility of free agency and indeterminism is less discussed than its mirror image, the question of the compatibility of free agency and determinism. It is, however, of great importance for our self-conception as free agents in our (arguably) indeterministic world. We begin by explicating the notions of indeterminism and free agency and by clarifying the interrelation of free agency and the human-specific notion of free will. We then situate our claim of the compatibility of free agency and indeterminism precisely in the landscape of the current debate on freedom and determinism, exposing an unhappy asymmetry in that debate. Then we proceed to make our case by describing the mathematically precise, physically motivated model of projective simulation, which employs indeterminism as a central resource for agency modeling. We argue that an indeterministic process of deliberation modeled by the dynamics of projective simulation can exemplify free agency under indeterminism, thereby establishing our compatibility claim: Free agency can develop and thrive in an indeterministic world.

Bell Test over Extremely High-Loss Channels: Towards Distributing Entangled Photon Pairs between Earth and the Moon

Quantum entanglement was termed "spooky action at a distance" in the well-known paper by Einstein, Podolsky, and Rosen. Entanglement is expected to be distributed over longer and longer distances in both practical applications and fundamental research into the principles of nature. Here, we present a proposal for distributing entangled photon pairs between Earth and the Moon using a Lagrangian point at a distance of 1.28 light seconds. One of the most fascinating features in this long-distance distribution of entanglement is as follows. One can perform the Bell test with human supplying the random measurement settings and recording the results while still maintaining spacelike intervals. To realize a proof-of-principle experiment, we develop an entangled photon source with 1 GHz generation rate, about 2 orders of magnitude higher than previous results. Violation of Bell's inequality was observed under a total simulated loss of 103 dB with measurement settings chosen by two experimenters. This demonstrates the feasibility of such long-distance Bell test over extremely high-loss channels, paving the way for one of the ultimate tests of the foundations of quantum mechanics.

Agency Beliefs Over Time and Across Cultures: Free Will Beliefs Predict Higher Job Satisfaction

In three studies, we examined the relationship between free will beliefs and job satisfaction over time and across cultures. Study 1 examined 252 Taiwanese real-estate agents over a 3-months period. Study 2 examined job satisfaction for 137 American workers on an online labor market over a 6-months period. Study 3 extended to a large sample of 14,062 employees from 16 countries and examined country-level moderators. We found a consistent positive relationship between the belief in free will and job satisfaction. The relationship was above and beyond other agency constructs (Study 2), mediated by perceived autonomy (Studies 2-3), and stronger in countries with a higher national endorsement of the belief in free will (Study 3). We conclude that free-will beliefs predict outcomes over time and across cultures beyond other agency constructs. We call for more cross-cultural and longitudinal studies examining free-will beliefs as predictors of real-life outcomes.

Relationships between short and fast brain timescales

Brain electric activity exhibits two important features: oscillations with different timescales, characterized by diverse functional and psychological outcomes, and a temporal power law distribution. In order to further investigate the relationships between low- and high- frequency spikes in the brain, we used a variant of the Borsuk-Ulam theorem which states that, when we assess the nervous activity as embedded in a sphere equipped with a fractal dimension, we achieve two antipodal points with similar features (the slow and fast, scale-free oscillations). We demonstrate that slow and fast nervous oscillations mirror each other over time via a sinusoid relationship and provide, through the Bloch theorem from solid-state physics, the possible equation which links the two timescale activities. We show that, based on topological findings, nervous activities occurring in micro-levels are projected to single activities at meso- and macro-levels. This means that brain functions assessed at the higher scale of the whole brain necessarily display a counterpart in the lower ones, and vice versa. Our topological approach makes it possible to assess brain functions both based on entropy, and in the general terms of particle trajectories taking place on donut-like manifolds. Condensed brain activities might give rise to ideas and concepts by combination of different functional and anatomical levels. Furthermore, cognitive phenomena, as well as social activity can be described by the laws of quantum mechanics; memories and decisions exhibit holographic organization. In physics, the term duality refers to a case where two seemingly different systems turn out to be equivalent. This topological duality holds for all the types of spatio-temporal brain activities, independent of their inter- and intra-level relationships, strength, magnitude and boundaries, allowing us to connect the physiological manifestations of consciousness to the electric activities of the brain.

Crickets alter wind-elicited escape strategies depending on acoustic context

Acoustic signals trigger various behaviours in insects such as courtship or escape from predators. However, it remains unknown whether insects utilize acoustic signals to recognize environmental contexts. The cricket is a prominent model insect for neuroethological studies on acoustic behaviour because female crickets exhibit positive phonotaxis in response to male calling songs, and flying crickets display avoidance behaviour for high-frequency sounds such as echolocation call of bats. The carrier frequency of these sounds is a major factor in determining whether they initiate these acoustic behaviours. Here, we examined the impacts of different frequencies of tone sounds on cercal-mediated escape behaviour, using a 5-kHz tone corresponding to the calling song and a 15-kHz tone serving as a trigger of avoidance behaviours. Neither frequency elicited a response in the standing cricket by itself, but they had different impacts on walking responses to airflow stimuli. While the 15-kHz tone reduced response probability, extended moving distance, and enhanced turn-angle variability, the 5-kHz tone had no effect. Although both frequencies of tones facilitated walking backward, the 15-kHz tone had a larger effect than the 5-kHz tone. These frequency dependencies of behavioural modulation suggest that crickets can recognize acoustic contexts and alter their escape strategy accordingly.

A Unifying Theory of Biological Function

A new theory that naturalizes biological function is explained and compared with earlier etiological and causal role theories. Etiological (or selected effects) theories explain functions from how they are caused over their evolutionary history. Causal role theories analyze how functional mechanisms serve the current capacities of their containing system. The new proposal unifies the key notions of both kinds of theories, but goes beyond them by explaining how functions in an organism can exist as factors with autonomous causal efficacy. The goal-directedness and normativity of functions exist in this strict sense as well. The theory depends on an internal physiological or neural process that mimics an organism’s fitness, and modulates the organism’s variability accordingly. The structure of the internal process can be subdivided into subprocesses that monitor specific functions in an organism. The theory matches well with each intuition on a previously published list of intuited ideas about biological functions, including intuitions that have posed difficulties for other theories.

Retrieval under stress decreases the long-term expression of a human declarative memory via reconsolidation

Acute stress impairs memory retrieval of several types of memories. An increase in glucocorticoids, several minutes after stressful events, is described as essential to the impairing retrieval-effects of stressors. Moreover, memory retrieval under stress can have long-term consequences. Through what process does the reactivated memory under stress, despite the disrupting retrieval effects, modify long-term memories? The reconsolidation hypothesis proposes that a previously consolidated memory reactivated by a reminder enters a vulnerability phase (labilization) during which it is transiently sensitive to modulation, followed by a re-stabilization phase. However, previous studies show that the expression of memories during reminder sessions is not a condition to trigger the reconsolidation process since unexpressed memories can be reactivated and labilized. Here we evaluate whether it is possible to reactivate-labilize a memory under the impairing-effects of a mild stressor. We used a paradigm of human declarative memory whose reminder structure allows us to differentiate between a reactivated-labile memory state and a reactivated but non-labile state. Subjects memorized a list of five cue-syllables associated with their respective response-syllables. Seventy-two hours later, results showed that the retrieval of the paired-associate memory was impaired when tested 20min after a mild stressor (cold pressor stress (CPS)) administration, coincident with cortisol levels increase. Then, we investigated the long-term effects of CPS administration prior to the reminder session. Under conditions where the reminder initiates the reconsolidation process, CPS impaired the long-term memory expression tested 24h later. In contrast, CPS did not show effects when administered before a reminder session that does not trigger reconsolidation. Results showed that memory reactivation-labilization occurs even when retrieval was impaired. Memory reactivation under stress could hinder -via reconsolidation- the probability of the traces to be expressed in the long term.

Predator personality and prey behavioural predictability jointly determine foraging performance

Predator-prey interactions play important roles in ecological communities. Personality, consistent inter-individual differences in behaviour, of predators, prey or both are known to influence inter-specific interactions. An individual may also behave differently under the same situation and the level of such variability may differ between individuals. Such intra-individual variability (IIV) or predictability may be a trait on which selection can also act. A few studies have revealed the joint effect of personality types of both predators and prey on predator foraging performance. However, how personality type and IIV of both predators and prey jointly influence predator foraging performance remains untested empirically. Here, we addressed this using a specialized spider-eating jumping spider, Portia labiata (Salticidae), as the predator, and a jumping spider, Cosmophasis umbratica, as the prey. We examined personality types and IIVs of both P. labiata and C. umbratica and used their inter- and intra-individual behavioural variation as predictors of foraging performance (i.e., number of attempts to capture prey). Personality type and predictability had a joint effect on predator foraging performance. Aggressive predators performed better in capturing unpredictable (high IIV) prey than predictable (low IIV) prey, while docile predators demonstrated better performance when encountering predictable prey. This study highlights the importance of the joint effect of both predator and prey personality types and IIVs on predator-prey interactions.

Visual motion processing subserving behavior in crabs

Motion vision originated during the Cambrian explosion more than 500 million years ago, likely triggered by the race for earliest detection between preys and predators. To successfully evade a predator's attack a prey must react quickly and reliably, which imposes a common constrain to the implementation of escape responses among different species. Thus, neural circuits subserving fast escape responses are usually straightforward and contain giant neurons. This review summarizes knowledge about a small group of motion-sensitive giant neurons thought to be central in guiding the escape performance of crabs to visual stimuli. The flexibility of the escape behavior contrasts with the stiffness of the optomotor response, indicating a task-dependent early segregation of visual pathways.

Free Will and Neuroscience: From Explaining Freedom Away to New Ways of Operationalizing and Measuring It

The concept of free will is hard to define, but crucial to both individual and social life. For centuries people have wondered how freedom is possible in a world ruled by physical determinism; however, reflections on free will have been confined to philosophy until half a century ago, when the topic was also addressed by neuroscience. The first relevant, and now well-known, strand of research on the brain correlates of free will was that pioneered by Libet et al. (1983), which focused on the allegedly unconscious intentions taking place in decisions regarded as free and voluntary. Libet’s interpretation of the so-called readiness potential (RP) seems to favor a sort of deflation of freedom (Soon et al., 2008). However, recent studies seem to point to a different interpretation of the RP, namely that the apparent build-up of the brain activity preceding subjectively spontaneous voluntary movements (SVM) may reflect the ebb and flow of the background neuronal noise, which is triggered by many factors (Schurger et al., 2016). This interpretation seems to bridge the gap between the neuroscientific perspective on free will and the intuitive, commonsensical view of it (Roskies, 2010b), but many problems remain to be solved and other theoretical paths can be hypothesized. The article therefore, proposes to start from an operationalizable concept of free will (Lavazza and Inglese, 2015) to find a connection between higher order descriptions (useful for practical life) and neural bases. This new way to conceptualize free will should be linked to the idea of “capacity”: that is, the availability of a repertoire of general skills that can be manifested and used without moment by moment conscious control. The capacity index, which is also able to take into account the differences of time scales in decisions, includes reasons-responsiveness and is related to internal control, understood as the agent’s ownership of the mechanisms that trigger the relevant behavior. Cognitive abilities, needed for one to have capacity, might be firstly operationalized as a set of neuropsychological tests, which can be used to operationalize and measure specific executive functions, as they are strongly linked to the concept of control. Subsequently, a free will index would allow for the search of the underlying neural correlates of the capacity exhibited by people and the limits in capacity exhibited by each individual.

Bad is freer than good: Positive-negative asymmetry in attributions of free will

Recent findings support the idea that the belief in free will serves as the basis for moral responsibility, thus promoting the punishment of immoral agents. We theorized that free will extends beyond morality to serve as the basis for accountability and the capacity for change more broadly, not only for others but also for the self. Five experiments showed that people attributed higher freedom of will to negative than to positive valence, regardless of morality or intent, for both self and others. In recalling everyday life situations and in classical decision making paradigms, negative actions, negatives outcomes, and negative framing were attributed higher free will than positive ones. Free will attributions were mainly driven by action or outcome valence, but not intent. These findings show consistent support for the idea that free will underlies laypersons' sense-making for accountability and change under negative circumstances.

When Choice Makes Sense: Menthol Influence on Mating, Oviposition and Fecundity in Drosophila melanogaster

The environment to which insects have been exposed as larvae and adults can affect subsequent behaviors, such as mating, oviposition, food preference or fitness. Experience can change female preference for oviposition, particularly in phytophagous insects. In Drosophila melanogaster, females avoid laying eggs on menthol rich-food when given the choice. Exposure to menthol during larval development reduces this aversion. However, this observation was not reproduced in the following generation. Recently, we have shown that oviposition-site preference (OSP) differs between wild-type D. melanogaster lines freely or forcibly exposed to menthol. After 12 generations, menthol "forced" lines still exhibit a persistent aversion to menthol whereas 'free-choice' lines show a decreased aversion for menthol rich-food. Here, we compare courtship behavior, mating and female fecundity in "forced" and "free-choice" lines, raised either on menthol rich-food (Menthol-lines) or on menthol-free food (Plain-lines). "Forced" males did not discriminate between decapitated virgin females of the two lines. They courted and mated with intact females of both "forced" lines in a comparable rate. However "forced" M-line males did mate significantly more rapidly with "forced" M-line females. In the "free-choice" procedure, P-line males show a similar pattern as "forced" males for discrimination ability and courtship. M-line males courted significantly more M-line females. Both 'free-choice' lines males mated significantly more with females of their own line. Female fecundity was assessed during 10 days in 'free-choice' lines. Menthol-line females laid more eggs during the first 4 days than female Plain-lines and parental control-line. The total number of eggs laid during the first 10 days of female adult life is comparable in M-line and parental control line. However, Menthol-line females laid eggs earlier than both parental control and Plain-lines. Our findings show that in D. melanogaster, as for OSP, mating and fecundity are more rapidly influenced when flies have a choice between alternative resources compared to flies permanently exposed to menthol.

Graph theoretical analysis of brain connectivity in phantom sound perception

Tinnitus is a phantom sound commonly thought of to be produced by the brain related to auditory deafferentation. The current study applies concepts from graph theory to investigate the differences in lagged phase functional connectivity using the average resting state EEG of 311 tinnitus patients and 256 healthy controls. The primary finding of the study was a significant increase in connectivity in beta and gamma oscillations and a significant reduction in connectivity in the lower frequencies for the tinnitus group. There also seems to be parallel processing of long-distance information between delta, theta, alpha1 and gamma frequency bands that is significantly stronger in the tinnitus group. While the network reorganizes into a more regular topology in the low frequency carrier oscillations, development of a more random topology is witnessed in the high frequency oscillations. In summary, tinnitus can be regarded as a maladaptive ‘disconnection’ syndrome, which tries to both stabilize into a regular topology and broadcast the presence of a deafferentation-based bottom-up prediction error as a result of a top-down prediction.

Ants determine their next move at rest: motor planning and causality in complex systems

To find useful work to do for their colony, individual eusocial animals have to move, somehow staying attentive to relevant social information. Recent research on individual Temnothorax albipennis ants moving inside their colony's nest found a power-law relationship between a movement's duration and its average speed; and a universal speed profile for movements showing that they mostly fluctuate around a constant average speed. From this predictability it was inferred that movement durations are somehow determined before the movement itself. Here, we find similar results in lone T. albipennis ants exploring a large arena outside the nest, both when the arena is clean and when it contains chemical information left by previous nest-mates. This implies that these movement characteristics originate from the same individual neural and/or physiological mechanism(s), operating without immediate regard to social influences. However, the presence of pheromones and/or other cues was found to affect the inter-event speed correlations. Hence we suggest that ants' motor planning results in intermittent response to the social environment: movement duration is adjusted in response to social information only between movements, not during them. This environmentally flexible, intermittently responsive movement behaviour points towards a spatially allocated division of labour in this species. It also prompts more general questions on collective animal movement and the role of intermittent causation from higher to lower organizational levels in the stability of complex systems.

The opposite effects of routine metabolic rate and metabolic rate during startle responses on variation in the predictability of behaviour in hermit crabs

Studies on animal behaviour have suggested a link between personality and energy expenditure. However, most models assume constant variation within individuals, even though individuals vary between observations. Such variation is called intraindividual variation in behaviour (IIV). We investigate if IIV in the duration of the startle response is associated with metabolic rates (MR) in the hermit crabPagurus bernhardus. We repeatedly measured startle response durations and MR during each observation. We used double hierarchical generalized linear models to ask whether among and IIV in behaviour was underpinned by MR. We found no association between the mean duration of the startle responses and either routine MR or MR during startle response. Nevertheless, we found that IIV increased with MR during startle responses and decreased with routine MR. These results indicate that crabs with higher MR during startle responses behave less predictably, and that predictability is reduced during exposure to elevated temperatures.

Novel plasticity rule can explain the development of sensorimotor intelligence

Grounding autonomous behavior in the nervous system is a fundamental challenge for neuroscience. In particular, self-organized behavioral development provides more questions than answers. Are there special functional units for curiosity, motivation, and creativity? This paper argues that these features can be grounded in synaptic plasticity itself, without requiring any higher-level constructs. We propose differential extrinsic plasticity (DEP) as a new synaptic rule for self-learning systems and apply it to a number of complex robotic systems as a test case. Without specifying any purpose or goal, seemingly purposeful and adaptive rhythmic behavior is developed, displaying a certain level of sensorimotor intelligence. These surprising results require no system-specific modifications of the DEP rule. They rather arise from the underlying mechanism of spontaneous symmetry breaking, which is due to the tight brain body environment coupling. The new synaptic rule is biologically plausible and would be an interesting target for neurobiological investigation. We also argue that this neuronal mechanism may have been a catalyst in natural evolution.