Processes All theories of behaviour make some assumptions about innateness and , thus , about the architecture of cognition , even though the issue has not always been explicitly addressed when the theory sets out its assumptions .sx In particular , all theories assume that the mechanisms of learning or development are themselves invariant , and are innate endowments of the organism .sx Behaviourist theories attribute all of behaviour to learned responses .sx Such a theory presumes an organism that is disposed to learn ; an organism that is innately endowed with the ability to associate a stimulus with a response .sx While the association between a particular S and a particular R is learned , behaviourists do not argue that organisms learn how to make associations ; associations are part of the organism's innate repertoire .sx Similarly the ability to discriminate among stimuli and to generalize across stimuli are innate and even though the basis of particular discriminations and generalizations may have to be learned .sx For Piaget's constructivist theory the mechanisms of assimilation and accommodation are innate and unchanging mechanisms .sx Piaget is quite explicit on this issue .sx He sees these mechanisms as evolution's answer to adaptation to the environment ( Piaget , 1967a/1971) .sx These mechanism support changing cognitive structures .sx The information processing framework also postulates a variety of innate mechanisms for learning and development .sx Many developmental theorists within the information processing framework have borrowed Piaget's constructs of assimilation and accommodation .sx However , the major mechanism of learning presumed by information processing theories in induction ( Holland , Holyoak , Nisbett and Thagard , 1986) .sx Induction is the formulation of general laws from particular cases as for example :sx I have seen lots of white swans .sx I have never seen any other colour of swan .sx Therefore , all swans are white .sx This reasoning is an impeccable piece of induction , although it is not logically valid .sx Philosophers have been much preoccupied by the fact that it is not logically valid .sx However , from a psychological viewpoint it is the mechanism itself that is of interest , not its logical status .sx Clearly , much human knowledge is based on much less than certainty .sx Bertrand Russell ( 1912 :sx p. 38 ) concluded that the inductive process itself is " incapable of being proved by an appeal to experience " but went on to argue that " we must either accept the inductive principle on the ground of its intrinsic evidence , or forgo all justification of our expectations about the future " .sx Any theory that postulates rule learning needs a mechanism for deriving rules from environmental regularities and induction serves this purpose admirably .sx The importance of induction is that it permits extrapolation from particular instances and provides a rule-based framework for cognitive processing .sx An example of what is commonly regarded as inductive learning is the child's derivation of the linguistic rule 'add -ed to the verb stem to form the past tense' .sx Initially children learn past tense forms on a word-by-word basis and thereby acquire the correct past tense form for both regular and irregular verbs ( e.g. , walked and took) .sx However , as more verbs are learnt the child notices that the majority of verbs form the past tense by adding -ed to the verb root .sx This results in an inductive generalization that all verbs form the past tense by adding -ed to the root .sx Application of this rule results in an overregularization of previously correct forms , so that taked will now replace took .sx The phenomenon will be discussed in more detail in chapter 7 .sx Here , the major point is to illustrate that an inductive inference can have powerful effects on the child's cognitive representations .sx There seems to be general agreement that the basic cognitive mechanisms of change are innate evolutionary products and are not themselves subject to developmental change .sx The content to which they apply does , of course , change with changing cognitive representations .sx Associations formed late in development may have a considerably more complex representational structure than associations formed in the first few days of life .sx Similarly , induction may produce relatively simple rules in early development but more complex rules in later development .sx The difference in complexity in both cases lies in the representation not in the mechanism that produced it .sx Structure For classical behaviourists the structure of cognition was an associative chain of 'mediating responses' .sx As the content of associations was entirely the product of learning , the structure of cognition was thus entirely the product of learning .sx For Piaget the structure of cognition was also a developmental product .sx However , Piaget thought that cognition was more than a copy of environmental associations , and he thought that it developed but was not necessarily learned ( Piaget , 1964) .sx The Piagetian view is that through the processes of assimilation and accommodation new cognitive structures emerge .sx Piaget argued that reflexes were the initial innate structures from which all other structures eventually develop .sx Information processing theories have a much more complex theory of the structure of cognition than either behaviourist or Piagetian theories .sx According to information processing theories , the cognitive system consists of a variety of interacting components .sx At a very general level , the major components are memory and attention .sx These components have various processes associated with them that transform and encode the input received .sx The system also has components that control the processing of information in accordance with the organism's goals and plans .sx Behaviourist , Piagetian , and many Information Processing theories regard the content of cognition as a developmental product .sx This seems an entirely reasonable position .sx Evolution could not possibly have prepared us for the particular information content that we receive .sx Content is a function of the particular environment that we inhabit - be it desert , or forest , or city ; of our particular culture ; and of our particular experience within an environment and a culture .sx At one level this analysis is true but it fails to do justice to the fact that regardless of the variation in content there are certain requirements placed by evolution on how content is processed .sx For example , different inputs must be treated as functionally similar by an organism in order for behaviour to be adaptive .sx This requires an innate ability to treat input in a categorical fashion .sx If an organism could not treat some stimuli as functionally equivalent to others , there would be no possibility of learning from experience because every encounter with the world would be unique .sx As we shall see in chapter 2 , the empirical evidence is completely in accord with this line of reasoning .sx Categorization is only one among a variety of structures imposed on information .sx During the course of development the child acquires a variety of increasingly complex organizational structures .sx The most notable example of this is human language .sx It has been a matter of considerable debate in recent years to what extent the structure of language ( and of other cognitive representations ) is learnt and to what extent it is innate .sx The issue was first raised by Chomsky ( 1959 , 1965 ) and it has not yet been completely resolved .sx We shall return to this issue in chapter 7 .sx What and How :sx A Second Pass .sx The question of how development occurs can be approached in several ways .sx Firstly , it is necessary to identify the learning mechanisms possessed by the cognitive system .sx Secondly , it is necessary to describe how these mechanisms act over time .sx Thirdly , there is the issue of how the environment in which a child learns , affects development .sx The first two issues are central to a theory of cognitive development ; the third is most relevant to issues of individual differences .sx The nature of learning mechanisms postulated by a theory is very largely dependent on its view of what develops .sx It is easiest to illustrate this by example .sx In some behaviourist theories of development ( e.g. , Bijou and Baer , 1961 ) what develops is a series of discriminative responses to environmental stimuli .sx Such a theory places no more demands on learning than that a child be capable of associating a stimulus and a response .sx Thus , the answer to how development occurs is by forming new associations or refining old ones .sx By contrast Piaget's theory of development regards the child as engaged in a continuous attempt to construct a theory of the world , while , at the same time , interpreting the world in the light of the child's current theory .sx Such a theory requires a give and take between the child's existing theory and new information , otherwise the system would never progress .sx Piaget accordingly postulates mechanisms of assimilation and accommodation as the primary learning mechanisms .sx Assimilation is the process by which new information is interpreted in the light of existing cognitive structures ; accommodation is the process by which cognitive structures change in the light of new information .sx Information processing theories place great emphasis on changes in the child's representation of the world .sx Accordingly , mechanisms of change are needed that shift the child from one representation of a task to another , more sophisticated representation of that task .sx The mechanisms of change proposed will vary as a function of the relation between the representations .sx Flavell ( 1972 ) discusses some of the varieties of representational change from an information processing perspective .sx However , it is noteworthy that the issue of how change occurs has rarely been given serious theoretical discussion within the information processing framework .sx As one further example consider Chomsky's ( 1965 ) view of language development .sx Chomsky argued that what develops during language development is a system of rules for a particular language .sx These rules are derived from a system of abstract grammatical rules shared by all languages .sx He argued further that this system could not be learnt from the environment by any conventional learning procedure .sx Nevertheless it must be possible for children to acquire these rules because children evidently do learn a language .sx Consequently , Chomsky proposed that , in some sense , general rules of language were innate although obviously the grammar and vocabulary of a particular language must be a product of interaction between environmental input and innate general rules .sx This interaction is conducted through the mechanism of testing hypotheses ( derived from the innate general rules ) about the structure of the particular language the child hears .sx It is evident from the three theoretical sketches that there is a strong inter-dependency between the what and the how of development .sx Chomsky is the most notable example here because he was led to question whether conventional accounts of how development proceeds could adequately explain the acquisition of the rules of grammar .sx Finding a negative answer Chomsky then proposed a greater role for biological inheritance than was common in theories of development .sx We shall return to the issue of innateness and biological inheritance in due course .sx For now , it can be remarked that the basic mechanisms of development postulated by most , if not all , theories are regarded as the product of evolution rather than of development .sx That is to say , the child is assumed to have an innate ability to make associations , or to engage in assimilation and accommodation .sx These mechanisms do not themselves require a developmental explanation within a theory of cognitive development .sx How do mechanisms act over time to produce change ?sx In a behaviourist theory associations are strengthened or weakened over time as a function of the child's history of reinforcement .sx In a Piagetian account of cognitive development the mechanisms of assimilation and accommodation serve as a filter between cognitive structures and new information .sx They act continually over time to modify existing cognitive structures .sx For Chomsky the major mechanism at the child's disposal is hypothesis-testing about the particular structure that language might have .sx The hypotheses to be tested are generated from the child's innate knowledge of the general rules of language .sx By continuous hypothesis testing the child gradually arrives at the correct particular structure of the language that he or she hears .sx Theories of cognition emphasize the creation and manipulation of representations of the environment .sx Cognitive development is , to a large extent , the development of the ability to create increasingly complex and sophisticated representations of the environment .sx The next two chapters will examine the origins of mental representations .sx 2 .sx Perpetual Development in Infancy .sx Method and Interpretation .sx Writing in 1890 , William James declared :sx " The baby , assailed by eyes , ears , nose , skin and entrails at once , feels it all one great blooming buzzing confusion " ( p. 488) .sx