An emerging class of theories concerning the functional structure of the brain takes the reuse of neural circuitry for various cognitive purposes to be a central organizational principle. According to these theories, it is quite common for neural circuits established for one purpose to be exapted (exploited, recycled, redeployed) during evolution or normal development, and be put to different uses, often without losing their original functions. Neural reuse theories thus differ from the usual understanding of the role of neural plasticity (...) (which is, after all, a kind of reuse) in brain organization along the following lines: According to neural reuse, circuits can continue to acquire new uses after an initial or original function is established; the acquisition of new uses need not involve unusual circumstances such as injury or loss of established function; and the acquisition of a new use need not involve (much) local change to circuit structure (e.g., it might involve only the establishment of functional connections to new neural partners). Thus, neural reuse theories offer a distinct perspective on several topics of general interest, such as: the evolution and development of the brain, including (for instance) the evolutionary-developmental pathway supporting primate tool use and human language; the degree of modularity in brain organization; the degree of localization of cognitive function; and the cortical parcellation problem and the prospects (and proper methods to employ) for function to structure mapping. The idea also has some practical implications in the areas of rehabilitative medicine and machine interface design. (shrink)

It is widely assumed that human learning and the structure of human languages are intimately related. This relationship is frequently suggested to derive from a language-specific biological endowment, which encodes universal, but communicatively arbitrary, principles of language structure (a Universal Grammar or UG). How might such a UG have evolved? We argue that UG could not have arisen either by biological adaptation or non-adaptationist genetic processes, resulting in a logical problem of language evolution. Specifically, as the processes of language change (...) are much more rapid than processes of genetic change, language constitutes a both over time and across different human populations, and, hence, cannot provide a stable environment to which language genes could have adapted. We conclude that a biologically determined UG is not evolutionarily viable. Instead, the original motivation for UG arises because language has been shaped to fit the human brain, rather than vice versa. Following Darwin, we view language itself as a complex and interdependent which evolves under selectional pressures from human learning and processing mechanisms. That is, languages themselves are shaped by severe selectional pressure from each generation of language users and learners. This suggests that apparently arbitrary aspects of linguistic structure may result from general learning and processing biases deriving from the structure of thought processes, perceptuo-motor factors, cognitive limitations, and pragmatics. (shrink)

The field of the philosophy of biology is flourishing in its aim to evaluate and rethink the view inherited from the previous century ---the Modern Synthesis. Different research areas and theories have come to the fore in the last decades in order to account for different biological phenomena that, in the first instance, fall beyond the explanatory scope of the Modern Synthesis. This thesis is anchored and motivated by this revolt in the philosophy of biology. -/- The central target in (...) this context is the possibility of naturalizing teleology, a classical nightmare for the history of biology itself. This requires, principally, understanding the causes of teleological explanations without assuming an unfashioned backward causation of sorts. As the riddles of teleological explanations are about their temporal dimension, I analyze different temporal scales of biological processes: evolutionary, developmental, and physiological. -/- The first one is the one defended in the context of the Modern Synthesis. As expected, one of the aims of this thesis is to evaluate the adequacy of an evolutionary account of teleological explanation. The scrutiny is negative. Evolutionary explanations in the context of the Modern Synthesis lack the necessary causal roots to naturalize teleology. Concerning the physiological scale, a long tradition pushed up by Kant and the organicist movement in the 20th century allows us to better understand how teleological explanations can be naturalized in physiological process. The key notions in this temporal scale are self-organization and the recursive, looped character of physiological process. While the physiological scale may be suitably accounted by contemporaries views, such as Autonomous Systems Theory, different central teleological phenomena remain unexplained from a purely physiological perspective. In particular, different issues concerning the (adaptive) construction of organism ---such as plasticity, robustness, variation, novelty, inheritance--- deserve an ontogenetic analysis. -/- The principal aim of this thesis is to provide a theory of teleological development that falls beyond the Modern Synthesis' framework and is prompted by different insights from the history of biology. I call it Agential Teleosemantics. It rests on two central pillars. First, that developmental processes, beyond any gene-centered stance, can be understood in informational terms; i.e. developmental processes are about the interaction of developmental resources conveying biological information. The second ingredient is agentivity, namely the idea that development is regulated by an agentive system according to the adaptiveness of the phenotypic outcomes produced. The role of agency in Agential Teleosemantic is equivalent to the role of genes in the Modern Synthesis: it is responsible for explaining the order and the adaptive complexity in the living realm. -/- The second target of this thesis regards the possibility of naturalizing intentional explanations in cognitive science. The central project involved in such an aim is known as teleosemantics. Classical teleosemantics however is etiological: it explains the teleofunctions of representational systems in terms of evolutionary processes. The different disputes in the contemporary philosophy of biology provide two insights to analyze teleosemantics in cognitive science. First, the challenges against the Modern Synthesis must be extended to the evolutionary approach of etiological teleosemantics. Second, as Agential Teleosemantics suggests an alternative source for teleofunctions ---ontogeny, I offer an attempt to integrate Agential Teleosemantics into cognitive science in order to provide an alternative teleosemantic project to understand intentional explanations in cognitive science. (shrink)

The concept of information has acquired a strikingly prominent role in contemporary biology. This trend is especially marked within genetics, but it has also become important in other areas, such as evolutionary theory and developmental biology, particularly where these fields border on genetics. The most distinctive biological role for informational concepts, and the one that has generated the most discussion, is in the description of the relations between genes and the various structures and processes that genes play a role in (...) causing. For many biologists, the causal role of genes should be understood in terms of their carrying information about their various products. That information might require the cooperation of various environmental factors before it can be "expressed," but the same can be said of other kinds of message. An initial response might be to think that this mode of description is entirely anchored in a set of well-established facts about the role of DNA and RNA within protein synthesis, summarized in the familiar chart representing the "genetic code," mapping DNA base triplets to amino acids. However, informational enthusiasm in biology predates even a rudimentary understanding of these mechanisms (Schrodinger 1944). And more importantly, current applications of informational concepts extend far beyond anything that can receive an obvious justification in terms of the familiar facts about the specification of protein molecules by DNA. This includes: 1 (i) The description of whole-organism phenotypic traits (including complex behavioral traits) as specified or coded for by information contained in the genes, (ii) The treatment of many causal processes within cells, and perhaps of the wholeorganism developmental sequence, in terms of the execution of a program stored in the genes, (iii) The idea that genes themselves, for the purpose of evolutionary theorizing, should be seen as, in some sense, "made" of information.. (shrink)

In the years leading up to the Second World War the ethologists Konrad Lorenz and Nikolaas Tinbergen, created the tradition of rigorous, Darwinian research on animal behavior that developed into modern behavioral ecology. At first glance, research on specifically human behavior seems to exhibit greater discontinuity that research on animal behavior in general. The 'human ethology' of the 1960s appears to have been replaced in the early 1970s by a new approach called ‘sociobiology’. Sociobiology in its turn appears to have (...) been replaced by an approach calling itself Evolutionary Psychology. Closer examination, however, reveals a great deal of continuity between these schools. At present, whilst Evolutionary Psychology is the most visible form of evolutionary psychology, empirical and theoretical research on the evolution of mind and behavior is marked by a diversity of ideas and approaches and it is far from clear which direction(s) the field will take in future. (shrink)

Creativity is generally thought to be the production of things that are novel and valuable. Humans are unique in the extent of their creativity, which plays a central role in innovation and problem solving, as well as in the arts. But what are the cognitive sources of novelty? More particularly, what are the cognitive sources of stochasticity in creative production? I will argue that they belong to two broad categories. One is associative, enabling the selection of goal-relevant ideas that have (...) become activated by happenstance in an unrelated context. The other relies on selection processes that leverage stochastic fluctuations in neural activity. At the same time, I will address a central puzzle, which is to understand how the outputs of stochastic processes can nevertheless generally fall within task constraints. While the components appealed to in the accounts that I offer are well established, the ways in which I combine them together are new. (shrink)

One of the most important recent developments in the study of concepts has been the resurgence of interest in nativist accounts of the human conceptual system. However, many theorists suppose that a key feature of neural organization—the brain’s plasticity—undermines the nativist approach to concept acquisition. We argue that, on the contrary, not only does the brain’s plasticity fail to undermine concept nativism, but a detailed examination of the neurological evidence actually provides powerful support for concept nativism.

This chapter investigates the extent to which claims of massive modular organization of the mind (espoused by some members of the evolutionary psychology research program) are consistent with the main elements of the simple heuristics research program. A number of potential sources of conflict between the two programs are investigated and defused. However, the simple heuristics program turns out to undermine one of the main arguments offered in support of massive modularity, at least as the latter is generally understood by (...) philosophers. So one result of the argument will be to force us to re-examine the way in which the notion of modularity in cognitive science should best be characterized, if the thesis of massive modularity isn’t to be abandoned altogether. What is at stake in this discussion, is whether there is a well-motivated notion of ‘module’ such that we have good reason to think that the human mind must be massively modular in its organization. I shall be arguing (in the end) that there is. (shrink)

The idea that some characteristics of an organism are explained by the organism's intrinsic nature, whilst others reflect the influence of the environment is an ancient one. It has even been argued that this distinction is itself part of the evolved psychology of the human species. The distinction played an important role in the history of philosophy as the locus of the dispute between Rationalism and Empiricism discussed in another entry in this encyclopedia. This entry, however, focuses on twentieth-century accounts (...) of the innate/acquired distinction. These accounts have for the most part been inspired by the sciences of mind and behaviour. (shrink)

Psychological evidence suggests that laypeople understand the world around them in terms of intuitive ontologies which describe broad categories of objects in the world, such as ‘person’, ‘artefact’ and ‘animal’. However, because intuitive ontologies are the result of natural selection, they only need to be adaptive; this does not guarantee that the knowledge they provide is a genuine reflection of causal mechanisms in the world. As a result, science has parted ways with intuitive ontologies. Nevertheless, since the brain is evolved (...) to understand objects in the world according to these categories, we can expect that they continue to play a role in scientific understanding. Taking the case of human evolution, we explore relationships between intuitive ontological and scientific understanding. We show that intuitive ontologies not only shape intuitions on human evolution, but also guide the direction and topics of interest in its research programmes. Elucidating the relationships between intuitive ontologies and science may help us gain a clearer insight into scientific understanding. (shrink)

This is an updated version of my Stanford Encyclopedia entry on Evolutionary Psychology. The 2018 version contains a new section on Human Nature as well as some new material on recent developments in Evolutionary Psychology.

The biomedical literature makes extensive use of the concept of a genetic program. So far, however, the nature of genetic programs has received no satisfactory elucidation from the standpoint of computer science. This unsettling omission has led to doubts about the very existence of genetic programs, on the grounds that gene regulatory networks lack a predetermined schedule of execution, which may seem to contradict the very idea of a program. I show, however, that we can make perfect sense of genetic (...) programs, if only we abandon the preconception that all computers have a von Neumann architecture. Instead, genetic programs instantiate the computational architecture of Post–Newell Production Systems. That is, genetic programs are unordered sets of conditional instructions, instructions that fire independently when their conditions are matched. For illustration I present a paradigm Production System that regulates the functioning of the well-known lac operon of E. coli. On close reflection it turns out that not only genes, but also proteins encode instructions. I propose, therefore, to rename genetic programs to biomolecular programs. Biomolecular and/or genetic programs, and the cellular computers than run them, are to be understood not as von Neumann computers, but as Post–Newell production systems. (shrink)

Cognitive scientists must understand not just what the mind does, but how it does what it does. In this paper, I consider four aspects of cognitive architecture: how the mind develops, the extent to which it is or is not modular, the extent to which it is or is not optimal, and the extent to which it should or should not be considered a symbol‐manipulating device (as opposed to, say, an eliminative connectionist network). In each case, I argue that insights (...) from developmental and evolutionary biology can lead to substantive and important compromises in historically vexed debates. (shrink)

This paper is an attempt at exploring the possibility of reconciling the two interpretations of biolinguistics which have been recently projected by Koster(Biolinguistics 3(1):61–92, 2009). The two interpretations—trivial and nontrivial—can be roughly construed as non-internalist and internalist conceptions of biolinguistics respectively. The internalist approach boils down to a conception of language where language as a mental grammar in the form of I-language grows and functions like a biological organ. On the other hand, under such a construal consistent with Koster’s (Biolinguistics (...) 3(1):61-92, 2009), the non-internalist version does not necessarily have to be externalist in nature; rather it is a matter of mutual reinforcement of biology and culture under the rubric of a co-evolutionary dynamics. Here it will be argued that the apparent dichotomy between these two conceptions of biolinguistics can perhaps be resolved if we have a richer synthesis that accounts for both internalism and non-internalism. (shrink)

The main thesis of Heyes' book is that all of the domain-specific learning mechanisms that make the human mind so different from the minds of other animals are culturally created and culturally acquired gadgets. The only innate differences are some motivational tweaks, enhanced capacities for associative learning, and enhanced executive function abilities. But Heyes' argument depends on contrasting cognitive gadgets with cognitive instincts, which are said to be innately specified. This ignores what has for some years been the mainstream nativist/anti-empiricist (...) view, which commits only to partially specified learning systems that become elaborated and built through domain-specific learning. (shrink)

Shoemaker (1996) presenteda prioriarguments against the possibility of ‘self‐blindness’, or the inability of someone, otherwise intelligent and possessed of mental concepts, to introspect any of her concurrent attitude states. Ironically enough, this seems to be a position that Gopnik (1993) and Carruthers (2006, 2008, 2009a,b) have proposed as not only possible, but as the actual human condition generally! According to this ‘Objectivist’ view, supposed introspection of one's attitudes is not ‘direct’, but an ‘inference’ of precisely the sort we make about (...) the attitudes of others, an inference that has the advantage in our own case ofonlyour own sensory data and memories, our behavior, and of the context we are in; i.e. we are all substantially self‐ blind. After sorting out a number of methodological and verbal issues, I argue, first, that thea prioriarguments against Objectivism don't succeed, and that Gopnik and Carruthers are right to regard the issue as an empirical one. On the other hand, I think they seriously underestimate the difficulty of establishing Objectivism. It is unlikely there is an inferential procedure from the data of pure sensation, behavior and context to the relevant self‐attributions that would be as spectacularly reliable as people manifestly seem to be. Moreover, there is a simpler model: the mind very likely consists of a panoply of sub‐routines some of whose outputs are ‘tagged’ for their having been so processed, rather in the way that software ‘documents’ are on standard computers. Introspection plausibly consists in a person's simply attending to distinctive constellations of these tags, even though they may lack phenomenal feels. This draws attention to an important independent fact: that much of phenomenology (or ‘what it's like’ to be in a certain state) may be constituted by facts that are not phenomenal. (shrink)

Shoemaker (1996) presenteda prioriarguments against the possibility of ‘self‐blindness’, or the inability of someone, otherwise intelligent and possessed of mental concepts, to introspect any of her concurrent attitude states. Ironically enough, this seems to be a position that Gopnik (1993) and Carruthers (2006, 2008, 2009a,b) have proposed as not only possible, but as the actual human condition generally! According to this ‘Objectivist’ view, supposed introspection of one's attitudes is not ‘direct’, but an ‘inference’ of precisely the sort we make about (...) the attitudes of others, an inference that has the advantage in our own case ofonlyour own sensory data and memories, our behavior, and of the context we are in; i.e. we are all substantially self‐ blind. After sorting out a number of methodological and verbal issues, I argue, first, that thea prioriarguments against Objectivism don't succeed, and that Gopnik and Carruthers are right to regard the issue as an empirical one. On the other hand, I think they seriously underestimate the difficulty of establishing Objectivism. It is unlikely there is an inferential procedure from the data of pure sensation, behavior and context to the relevant self‐attributions that would be as spectacularly reliable as people manifestly seem to be. Moreover, there is a simpler model: the mind very likely consists of a panoply of sub‐routines some of whose outputs are ‘tagged’ for their having been so processed, rather in the way that software ‘documents’ are on standard computers. Introspection plausibly consists in a person's simply attending to distinctive constellations of these tags, even though they may lack phenomenal feels. This draws attention to an important independent fact: that much of phenomenology (or ‘what it's like’ to be in a certain state) may be constituted by facts that are not phenomenal. (shrink)

ITA: In questo articolo analizzerò la differenza tra il concetto di ereditarietà e quello di ereditabilità. In primo luogo, evidenzierò come i due concetti derivino storicamente da differenti tradizioni nello studio della variabilità fenotipica e del rapporto genotipo-fenotipo. Secondariamente, illustrerò gli aspetti teorici e metodologici alla base dei due concetti, che sono peraltro collegati a differenti aree delle scienze biologiche. Infine, spiegherò brevemente come si sia recentemente tentato, con molte difficoltà, di connettere lo studio dei meccanismi dell’ereditarietà allo studio dell’ereditabilità. (...) Nel discutere le questioni di cui sopra, farò riferimento a tratti psicologici come l’intelligenza dal momento che è proprio dallo studio di questo tipo di tratti che sono emersi i maggiori problemi teorici e metodologici, nonché le controversie più intense. -/- ENG: In this paper, I analyse the distinction between heredity and heritability. First, I highlight that the two concepts derive from different historical traditions in the study of phenotypic variability and of the genotype-phenotype relationship. Second, I illustrate the theoretical and methodological aspects connected to the two concepts, which are traditionally associated with different areas of biological research. Then, I focus on recent attempts aimed at connecting with each other the analysis of heredity and of heritability. In my discussion, I shall often refer to human psychological traits such as intelligence. Indeed, most theoretical and methodological discussions have emerged with respect to the study of these traits. (shrink)

A number of debates in philosophy of biology and psychology, as well as in their respective sciences, hinge on particular views about the relationship between genotypes and phenotypes. One such view is that the genotype-phenotype relationship is relatively straightforward, in the sense that a genome contains the ?genes for? the various traits that an organism exhibits. This leads to the assumption that if a particular set of traits is posited to be present in an organism, there must be a corresponding (...) number of genes in that organism's genome to account for those traits. This assumption underlies what can be called the ?counting argument,? in which empirical estimates of the number of genes in a genome are used to support or refute particular hypotheses in philosophical debates about biology and psychology. In this paper, we assess the counting argument as it is used in discussions of the alleged massive modularity of the brain, and conclude that this argument cannot be upheld in light of recent philosophical work on gene concepts and empirical work on genome complexity. In doing so, we illustrate that there are those on both sides of the debate about massive modularity who rely on an incorrect view of gene concepts and the nature of the genotype-phenotype relationship. (shrink)

This dissertation is devoted to dual-process theories, widely discussed in the recent literature in cognitive science. The author argues for a significantly modified version of the account suggested by Samuels (2009), replacing the distinction between ‘Systems’ with a distinction between ‘Types of processes,’ which allows a critique of both the (only) modularist accounts and the accounts describing a deep difference between two systems each having their specificities (functional, phenomenological and neurological). In the account of dual-process theories developed here, the distinction (...) between ‘Types of processes’ is considered, a priori, only as a heuristic distinction allowing to better understand the mind and to explain some of its properties. The main idea defended in this dissertation is that cognitive processes should be distinguished by their position in a multidimensional conceptual space allowing researchers to consider all of the characteristics and peculiarities attributed to a process, which is preferable to accounts forcing the process into either ‘System’ or either ‘Type’ identified in the most influential approaches (cf. Evans, 2008). Once this research program is in place, it will become possible to revise the concepts used and the categories defined to ground anew some of the notions we find in the literature (‘module,’ ‘System 1 / 2,’ etc.). The argument is made in three steps: -/- 1) The first chapter aims at a clarification of the notion of ‘module’ commonly used in cognitive science. Against the accounts aiming at a weakening of the notion in order to classify all of the mind’s processes as modular, the author – following most notably Faucher and Poirier (2009) and Samuels (2006) – casts doubt on how this notion is used by many influential authors, particularly in evolutionary psychology (e.g. Barrett, Carruthers, Cosmides, Tooby). -/- 2) The objective of the second chapter is to present, examine and criticize many dual-process theories and to suggest that no theory currently discussed is adequate to describe the architecture of mind. The accounts, especially influent or representative, suggested by Stanovich (1999; 2004; 2009), by Evans (2008; 2009), by Lieberman (2007; 2009) and by Carruthers (2006; 2009), are examined. -/- 3) In the third chapter, the author criticizes the framework developed by Samuels (2009) before developing his own account of dual-process theories and discussing some of its advantages. (shrink)

Despite its strengths, Leech et al.'s model fails to address the important benefits that derive from self-explanation and task feedback in analogical reasoning development. These components encourage explicit, self-reflective processes that do not necessarily link to knowledge accretion. We wonder, therefore, what mechanisms can be included within a connectionist framework to model self-reflective involvement and its beneficial consequences.

Our target article argued that a genetically specified Universal Grammar (UG), capturing arbitrary properties of languages, is not tenable on evolutionary grounds, and that the close fit between language and language learners arises because language is shaped by the brain, rather than the reverse. Few commentaries defend a genetically specified UG. Some commentators argue that we underestimate the importance of processes of cultural transmission; some propose additional cognitive and brain mechanisms that may constrain language and perhaps differentiate humans from nonhuman (...) primates; and others argue that we overstate or understate the case against co-evolution of language genes. In engaging with these issues, we suggest that a new synthesis concerning the relationship between brains, genes, and language may be emerging. (shrink)

Leech et al.'s model proposes representing relations as primed transformations rather than as structured representations (explicit representations of relations and their roles dynamically bound to fillers). However, this renders the model unable to explain several developmental trends (including relational integration and all changes not attributable to growth in relational knowledge). We suggest looking to an alternative computational model that learns structured representations from examples.

David Buller and Valerie Hardcastle have argued that various discoveries about the genetics and nature of brain development show that most ?central? psychological mechanisms cannot be adaptations because the nature of the contribution from the environment on which they are based shows they are not heritable. Some philosophers and scientists have argued that a strong role for the environment is compatible with high heritability as long as the environment is highly stable down lineages. In this paper I support this view (...) by arguing that the discoveries Buller and Hardcastle refer to either do not show as strong a role for the environment as they suggest, or these discoveries show that the brain's developmental process depends in many cases on input from the environment that is highly stable across generations. (shrink)

In this response, we reiterate the importance of development (both ontogenetic and phylogenetic) in the understanding of a complex cognitive skill – analogical reasoning. Four key questions structure the response: Does relational priming exist, and is it sufficient for analogy? What do we mean by relations as transformations? Could all or any relations be represented as transformations? And what about the challenge of more complex analogies? In addressing these questions we bring together a number of supportive commentaries, strengthening our emergentist (...) case for analogy (in particular with insights from comparative psychology), and review new supportive evidence. We also rebut those commentaries that ignore development at their peril. Along the way, we revisit the main assumptions underlying the analogy as relational priming (ARP) account of analogy, clarifying and elaborating as necessary. (shrink)

Bio-art epitomizes a coalescence of art and sciences. It is an emerging contemporary artistic practice that uses a wide range of traditional artistic media interwoven with new artistic media that are biological in nature. This includes molecules, genes, cells, tissues, organs, living organisms, ecological niches, landscapes and ecosystems. In addition, bio-art expands into conceptual art using biological processes such as growth, cell division, photosynthesis and concepts of the origin of life and evolution, explaining them as new artistic media. In this (...) time of global challenges, bio-art communicates thoughts and feelings that involve relationships between the artist, science, public and the biological organism or biological concept. This article reviews the major challenges and driving forces that contributed to emerging biology-centered art and design. (shrink)

We propose that there are four fundamental kinds of metaphor that are uniquely mapped onto specific brain ‘‘networks’’ and present preliterate (i.e., evolutionary, including before the appearance of written language in the historical record), prelinguistic (i.e., developmental, before the appearance of speech in human development), and extralinguistic (i.e., neuropsychological, cognitive) evidence supportive of this view. We contend that these basic metaphors are largely nonconceptual and entail (a) perceptual–perceptual, (b) cross-modal, (c) movement–movement, and (d) perceptual-affective mappings that, at least, in the (...) initial stages of processing may operate largely outside of conscious awareness. In opposition to our basic metaphor theory (BmT), the standard theory (SmT) maintains that metaphor is a conceptual mapping from some base domain to some target domain and/or represents class-inclusion (categorical) assertions. The SmT captures aspects of secondary or conceptual metaphoric relations but not primary or basic metaphoric relations in our view. We believe our theory (BmT) explains more about how people actually recognize or create metaphoric associations across disparate domains of experience partly because they are ‘‘pre-wired’’ to make these links. (shrink)

Gary Marcus has written a very interesting book about mental development from a nativist perspective. For the general readership at which the book is largely aimed, it will be interesting because of its many informative examples of the development of cognitive structures and because of its illuminating explanations of ways in which genes can contribute to these developmental processes. However, the book is also interesting from a theoretical point of view. Marcus tries to make nativism compatible with the central arguments (...) that anti-nativists use to attack nativism and with many recent discoveries about genetic activity and brain development. In so doing, he reconfigures the nativist position to a considerable extent. (shrink)