Papers by Raffaele Calabretta
In this article, we report the results of an e-democracy experiment in which a group of supporter... more In this article, we report the results of an e-democracy experiment in which a group of supporters of a large political party were asked to debate online about ways to reform the electoral law. We compare a traditional forum with an online collaborative argumentation platform to capture the various proposals and their associated pros and cons. The aim of this study is to assess the capability of this tool to support online collective deliberation in a real-world case, as compared to an online discussion supported by a forum. By comparing users’ experience across several metrics related to usability, activity levels, and quality of collaboration, our findings show that the forum produced more activity and ideas and its users perceived a better quality of the collaboration process, while the argumentation tool helped to reduce the amount of self-referential arguments and encourage viewing and rating of others’ posts.
The most successful democratic innovations have been able to promote good deliberation by employi... more The most successful democratic innovations have been able to promote good deliberation by employing small discussion groups (5 to 15 participants). In this paper we show that it is possible to design online democratic innovations that can induce good argumentation in large groups of more than 100 participants. The essay is based on a field experiment implemented in a real life democratic innovation designed to promote good e-deliberation and organized in collaboration with the largest online community of the Italian Democratic Party (Insieme per il PD). The field experiment aims to explore the possibility of improving the quality of e-deliberation by comparing the performance of a traditional forum with the performance of an argument mapping software structured to optimize argumentation (Deliberatorium). With respect to a traditional forum technology the argument mapping software 1) does not significantly reduce participation, 2) reduces the total number of ideas generated by the users, and 3) increases the exchange of arguments in favor of and against each proposed idea. Given the centrality of good argumentation in promoting the quality of deliberation, this experiment shows a promising first step in scaling-up deliberation.
What genotypic features explain the evolvability of organisms that have to accomplish many differ... more What genotypic features explain the evolvability of organisms that have to accomplish many different tasks? The genotype of behaviorally complex organisms may be more likely to encode modular neural architectures because neural modules dedicated to distinct tasks avoid neural interference, i.e. the arrival of conflicting messages for changing the value of connection weights during learning. However, if the connection weights for the various modules are genetically inherited, this raises the problem of genetic linkage: favorable mutations may fall on one portion of the genotype encoding one neural module and unfavorable mutations on another portion encoding another module. We show that this can prevent the genotype from reaching an adaptive optimum. This effect is different from other linkage effects described in the literature and we argue that it represents a new class of genetic constraints. Using simulations we show that sexual reproduction can alleviate the problem of genetic linkage by recombining separate modules all of which incorporate either favorable or unfavorable mutations. We speculate that this effect may contribute to the taxonomic prevalence of sexual reproduction among higher organisms. In addition to sexual recombination, the problem of genetic linkage for behaviorally complex organisms may be mitigated by entrusting evolution with the task of finding appropriate modular architectures and learning with the task of finding the appropriate connection weights for these architectures.
Npl, 1996
In nature the genotype of many organisms exhibits diploidy, i.e., it includes two copies of every... more In nature the genotype of many organisms exhibits diploidy, i.e., it includes two copies of every gene. In this paper we describe the results of simulations comparing the behavior of haploid and diploid populations of ecological neural networks living in both fixed and changing environments. We show that diploid genotypes create more variability in fitness in the population than haploid genotypes and buffer better environmental change; as a consequence, if one wants to obtain good results for both average and peak fitness in a single population one should choose a diploid population with an appropriate mutation rate. Some results of our simulations parallel biological findings.
Biological Theory, 2008
The paper examines the question of how learning multiple tasks interacts with neural architecture... more The paper examines the question of how learning multiple tasks interacts with neural architectures and the flow of information through those architectures. It approaches the question by using the idealization of an artificial neural network where it is possible to ask more precise questions about the effects of modular versus nonmodular architectures as well as the effects of sequential vs. simultaneous learning of tasks. While prior work has shown a clear advantage of modular architectures when the two tasks must be learned at the same time from the start, this advantage may disappear when one task is first learned to a criterion before the second task is undertaken. Nonmodular networks, in some cases of sequential learning, achieve success levels comparable to those of modular networks. In particular, if a nonmodular network is to learn two tasks of different difficulty and the more difficult task is presented first and learned to a criterion, then the network will learn the second easier one without permanent degradation of the first one. In contrast, if the easier task is learned first, a nonmodular task may perform significantly less well than a modular one. It seems that the reason for these difference has to do with the fact that the sequential presentation of the more difficult task first minimizes interference between the two tasks. More broadly, the studies summarized in this paper seem to imply that no single learning architecture is optimal for all situations.
To i n vestigate the issue of how modularity emerges in nature, we present an Arti cial Life mode... more To i n vestigate the issue of how modularity emerges in nature, we present an Arti cial Life model that allow us to reproduce on the computer both the organisms (i.e., robots that have a genotype, a nervous system, and sensory and motor organs) and the environment in which organisms live, behave and reproduce. In our simulations neural networks are evolutionarily trained to control a mobile robot designed to keep an arena clear by p i c king up trash objects and releasing them outside the arena. During the evolutionary process modular neural networks, which control the robot's behavior, emerge as a result of genetic duplications. Preliminary simulation results show that duplication-based modular architecture outperforms the nonmodular architecture, which represents the starting architecture in our simulations. Moreover, an interaction between mutation and duplication rate emerges from our results. Our future goal is to use this model in order to explore the relationship between the evolutionary emergence of modularity and the phenomenon of gene duplication.
Molti fenomeni biologici non possono essere studiati in un laboratorio reale o perché avvengono s... more Molti fenomeni biologici non possono essere studiati in un laboratorio reale o perché avvengono su scale temporali troppo lunghe o perché riguardano oggetti troppo grandi o troppo piccoli, o perché gli esperimenti non sono eticamente possibili, o per diversi altri motivi. Una strada alternativa per la creazione di ambienti di apprendimento è quella che porta alla costruzione di laboratori sperimentali virtuali o simulati. In particolare, un Laboratorio di Vita Artificiale consente agli utenti di affrontare i complessi formalismi matematici che descrivono i fenomeni biologici mediante un interfaccia immediata e familiare, che si presenta di volta in volta sotto forma di video- games, di esperimento e, finanche, di progettazione hardware e software. A differenza di altri ausili didattici multimediali in cui si sfrutta la potenza di calcolo dei computer per navigare all'interno di banche dati, un Laboratorio di Vita Artificiale permette l'apprendimento di nozioni base di biolog...
Brain/mind modularity is a contentious issue in cognitive science. Cognitivists tend to conceive ... more Brain/mind modularity is a contentious issue in cognitive science. Cognitivists tend to conceive of the mind as a set of distinct specialized modules and they believe that this rich modularity is basically innate. Cognitivist modules are theoretical entities which are postulated in boxes-and-arrows models used to explain behavioral data. On the other hand, connectionists tend to think that the mind is a more homogeneous system that basically genetically inherits only a general capacity to learn from experience and that if there are modules they are the result of development and learning rather than being innate. In this chapter we argue for a form of connectionism which is not anti-modularist or anti-innatist. Connectionist modules are anatomically separated and/or functionally specialized parts of a neural network and they may be the result of a process of evolution in a population of neural networks. The new approach, Evolutionary Connectionism, does not only allow us to simulate ...
We present the experimental structure of the book Il film delle emozioni ('The movie of emoti... more We present the experimental structure of the book Il film delle emozioni ('The movie of emotions', 2007), which makes an attempt at using a narrative structure for communicating the most recent scientific knowledge relative to the functioning of the brain (the amygdala) and, particularly, to emotion management. This book can be defined as an essay on emotions in the form of a novel, or as a laboratory fiction novel (lab-lit). The book is borderline literature that mixes registers and genres: the novel, an autobiography, a scientific paper about emotions, a diary, an emotional trainer, rich of link and bibliographic references, but also a manual on how to live. The book structure is composite: is not divided in chapters, but is a digital miscellany, made up of a variety of materials (i.e., computer files). A feature of the novel is that its structure is not causal, instead it is conceived and realized to convey the novel's themes and some scientific findings and theories,...
Un saggio sulle emozioni in forma di romanzo. Un romanzo felicemente sperimentale, che va oltre l... more Un saggio sulle emozioni in forma di romanzo. Un romanzo felicemente sperimentale, che va oltre l'eterogenità dell'insieme. Brani diaristici, pezzi di articolo scientifico, scarti di e-mail, sceneggiatura cinematografica, elenchi di film e libri. Una struttura mossa, composita, che evoca Perec. Immedesimazione e tensione narrativa sono prodotte dal personaggio che dice io - Gabriele - vero centro magnetico di un romanzo modulare a tratti quasi ipertestuale. Vivo, corposo, palpitante, oscillante fra paura e rabbia, autocommiserazione e esaltazione, ironia e dramma, tra un bisogno di riconoscimento sociale e il legame con la compagna. Chi racconta ha un tono sincero e sinceramente ci parla delle sue nevrosi e contraddizioni, e della sua ricerca della felicità, alternando una terminologia scientifica con frasi e modi gergali, mescolando cultura alta e attualità politica. A lettura finita ne sappiamo molto di più sul cervello, su come funzionano emozioni e sentimenti, su come po...
The movie of emotions: A novel's experimental modular structure that conveys scientific theor... more The movie of emotions: A novel's experimental modular structure that conveys scientific theories and research findings. There is a growing trend of the use of literary techniques for the popularization of scientific findings and theories (e.g., Lloyd, 2003; vedi Eakin, 2003). The book Il film delle emozioni ('The movie of emotions'; Calabretta, 2007, second edition) makes an attempt at using a narrative structure for communicating the most recent scientific knowledge relative to the functioning of the brain and, particularly, to emotion management. But the book is not a scientific essay on emotions in a traditional way. It was defined as "a happily unclassifiable book, therefore, an experimental one". Since there is both one main character and narrative tension, perhaps the book can be defined as an essay on emotions in the form of a novel. The novel describes the several attempts of the main character Gabriele to write the script of a movie for emotional train...
The purpose of this paper is to present the complex structure of the book “The movie of emotions”... more The purpose of this paper is to present the complex structure of the book “The movie of emotions”. This structure is not organized into chapters and is characterized by several beginnings and conclusions, is branched, fractalic, duplicated, modular and specialized. If one wants to define a specific novel as a complex system, then that novel has obviously to be not only complex but also “interesting” for readers. “The movie of emotions” is a very experimental novel that can be defined both complex and interesting. It can be defined as complex because its structure reproduces some properties of complex systems, and because the amount of information necessary to describe its multiple levels of structure organization is big and has to do with different literary styles and registers. It can be defined as interesting on the basis of reviews. The book is a “structural science-in-fiction novel”, a new literary genre in which novel’s structure communicates scientific information. By reading ...
We present an "ab initio" method that tries to determine the tertiary structure of unknown protei... more We present an "ab initio" method that tries to determine the tertiary structure of unknown proteins by modelling the folding process without using potentials extracted from known protein structures. We have been able to obtain appropriate matrices of folding potentials, i.e. 'forces' able to drive the folding process to produce correct tertiary structures, using a genetic algorithm. Some initial simulations that try to simulate the folding process of a fragment of the crambin that results in an alpha-helix, have yielded good results. We discuss some general implications of an Artificial Life approach to protein folding which makes an attempt at simulating the actual folding process rather than just trying to predict its final result.
... in complex organisms, and the observed fact that sexual populations tend to have higher mutat... more ... in complex organisms, and the observed fact that sexual populations tend to have higher mutation rates than asexual populations (Maynard Smith, 1978 ... did we discover that it can be linked to the hypothesis of duplication of cortical areas proposed by Allman & Kaas (1971; see ...
Cellular Automata: Research Towards Industry, 1998
ChemInform, 1991
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Perspectives in Neural Computing, 1998
Biological Theory, 2008
The paper examines the question of how learning multiple tasks interacts with neural architecture... more The paper examines the question of how learning multiple tasks interacts with neural architectures and the flow of information through those architectures. It approaches the question by using the idealization of an artificial neural network where it is possible to ask more precise questions about the effects of modular versus nonmodular architectures as well as the effects of sequential vs. simultaneous learning of tasks. While prior work has shown a clear advantage of modular architectures when the two tasks must be learned at the same time from the start, this advantage may disappear when one task is first learned to a criterion before the second task is undertaken. Nonmodular networks, in some cases of sequential learning, achieve success levels comparable to those of modular networks. In particular, if a nonmodular network is to learn two tasks of different difficulty and the more difficult task is presented first and learned to a criterion, then the network will learn the second easier one without permanent degradation of the first one. In contrast, if the easier task is learned first, a nonmodular task may perform significantly less well than a modular one. It seems that the reason for these difference has to do with the fact that the sequential presentation of the more difficult task first minimizes interference between the two tasks. More broadly, the studies summarized in this paper seem to imply that no single learning architecture is optimal for all situations.
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Papers by Raffaele Calabretta