INTRODUCTIONAuthors, in both the area of experimental research and the area of computer simulation in developmental psychology, have considered neural networks (including connectionist PDP networks) as important process models ofWe would like to thank Han van der Maas, Anny Bosman, and the reviewers for their helpful comments on this article.Correspondence and requests for reprints should be sent to Maartje Raijmakers, Department of Psychology, University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands, E-mail: op_raijmakers@macmaiI.psy.uva.nl. 101 102 RAIJMAKERS, VAN KOTEN, AND MOLENAARcognitive development (Bates & Elman, 1993; Grossberg, 1980; McClelland, 1989; Plunkett & Sinha, 1992;Siegler, 1989). Contrary to the relatively fixed architectures of the symbol manipulating production systems commonly employed in cognitive science, neural networks develop their knowledge base in adaptive interaction with the environment. In this respect, neural networks are compatible with epigenetical theory, according to which such interactions are the prime source of the emergence of more powerful cognitive structures (cf. Molenaar, 1986b). PDP networks, introduced by McClelland, Rumelhart, and the PDP research group (1986), constitute a distinct subset of neural network models. They are thought to be capable of both acquiring symbolic systems up to the level of natural language and modeling specific developmental phenomena like the accommodation process, which lies at the heart of Piaget's theory of developmental change (McClelland & Jenkins, 1991, p. 69). The applicability of those models to developmental processes is mainly studied by comparing their performance with empirical data, pertaining to, for example, English verb morphology, concept formation and vocabulary growth, and stagewise cognitive development (Plunkett & Sinha, 1992).In this article, we will take a closer look at the latter application: the simulation of stagewise cognitive development. McClelland and others (e.g., McClelland & Jenkins, 1991) have drawn two main conclusions from their study of a PDP network that learns the balance scale task. First, the learning behaviour can be described as the acquisition of increasingly complex rules. This conclusion is based on an application of Siegler's (1981) rule-assessment methodology, in which observed response patterns are classified as being generated by one of four distinct rules. Second, the acquisition of more complex rules by the network appears to proceed in a stagewise manner. That is, the performance of the network is for a while consistent with a particular arule and then suddenly shifts to another rule.However, questions have been raised about the evidence on which these conclusions are based. The four increasingly complex rules in Siegler's (1981) scheme constitute a measurement scale with discrete values. Hence, an application of this scheme to the learning behaviour of the network implies that the observed response patterns, which can vary continuously along multiple dimens...

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We experimentally study the effects of introducing a forward market and of increasing the number of competitors in a quantity-setting market under strictly convex production costs. Our key interest is to better understand which of these two remedies is more effective at enhancing competition. Allaz and Vila (1993) theorized that forward markets can have a pro-competitive effect under linear production costs. Le Coq and Orzen (2006) and Brandts, Pezanis-Christou and Schram (2008) investigated this and related issues experimentally. All three experiments (including ours) support the prediction by Allaz and Vila (1993) that introducing a forward market does indeed intensify competition. The results of the present study, however, differ from previous experimental results in that we find the forward market to be the more effective remedy. Brandts et al. (2008) increase the number of competitors by entry, which thus increases the aggregate stock of production assets and makes output cheaper. In contrast, we increase the number of competitors by divestiture, which leaves the aggregate stock of production 2/18 assets constant. Our results address an important policy issue and provide tentative evidence on the competition-enhancing effect of forward markets, which can be considered a behavioral remedy.

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Abstract:The relationship between risk in the environment, risk aversion and inequality aversion is not well understood. Theories of fairness have typically assumed that pie sizes are known ex-ante. Pie sizes are, however, rarely known ex ante. Using two simple allocation problems-the Dictator and Ultimatum game-we explore whether, and how exactly, unknown pie sizes with varying degrees of risk ("endowment risk") influence individual behavior. We derive theoretical predictions for these games using utility functions that capture additively separable constant relative risk aversion and inequity aversion. We experimentally test the theoretical predictions using two subject pools: students of Czech Technical University and employees of Prague City Hall. We find that: (1) Those who are more risk-averse are also more inequality-averse in the Dictator game (and also in the Ultimatum game but there not statistically significantly so) in that they give more; (2) Using the within-subject feature of our design, and in line with our theoretical prediction, varying risk does not influence behavior in the Dictator game, but does so in the Ultimatum game (contradicting our theoretical prediction for that game); (3) Using the within-subject feature of our design, subjects tend to make inconsistent decisions across games; this is true on the level of individuals as well as in the aggregate. This latter finding contradicts the evidence in Blanco et al. (2011); (4) There are no subject-pool differences once we control for the elicited risk attitude and demographic variables that we collect. OPEN ACCESSGames 2013, 4 209

We try to better understand the comparative advantages of structural and behavioral remedies of deregulation in electricity markets, an eminent policy issue for which the experimental evidence is scant and problematic.Specifically, we investigate theoretically and experimentally the effects on competition of introducing a forward market which the European Commission classifies as a behavioral remedy. We compare this scenario with its best alternative, the structural remedy of adding one more competitor by divestiture. Our study contributes to the literature by introducing more realistic cost configurations, by teasing apart competition effect and asset effect, and by investigating competitor numbers that reflect the market concentration in the European electricity industries. Our experimental data suggest that introducing a forward market has a positive effect on the aggregate supply in markets with two or three major competitors, configurations typical for the newly accessed and the old European Union member states, respectively. Introducing a forward market also increases efficiency. 1 Corresponding author 2/101In contrast to previous findings, our data furthermore suggest that the effect of introducing a forward market is stronger than adding one more competitor. We thus provide evidence that behavioral remedies may be more effective than structural ones. Our data hence suggest that competition authorities are well advised, in line with EU law (European Commission, 2006a, p.11), to focus on introducing, and facilitating the proper functioning of, forward markets rather than on lowering market concentration by divestiture., -, -. Rearranging this equation yields , -( , -) ( ) (( ) ) ( , -, -) , -. 5/101when none of them had sold. This prisoner's-dilemma type result is standard textbook fare (e.g., Binmore 2007, chapter 10).Allaz and Vila (1993) model the competition as a one-shot game. The Nash equilibrium of a one-shot game and that of a repeated game with predictable ending are theoretically (albeit not necessarily behaviorally; see Selten (1978Selten ( , 1991 identical. This makes the Allaz and Vila model a fitting theoretical benchmark for an experiment with a fixed, or predictable, number of periods. Of course, in the real world the number of periods may not be fixed, or predictable, and the Nash equilibrium of the stage game is one of many equilibria, some of which may be collusive: see Liski and Montero (2006). Since all treatments have the same number of rounds, between-treatment results ought to be nonetheless informative.We compare the results of introducing a forward market with those of the best alternative remedy: reducing market concentration by divestiture. We do so for competitor numbers that arguably reflect better the market concentration in the old European states than previous literature has done. We also use realistic cost configurations and tease apart competition and asset effect.We show that, theoretically and behaviorally, the effects of introducing a forward market might be larger than...

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