Library of Excerpts

Connections Between Heterochrony and Developmental Psychology

[abstract] "The hypothesis of a neurodevelopmental aetiology of manic-depressive psychosis and schizophrenia is based on the relation between onset of puberty and the final regressive events in the central nervous system (elimination of 40% of neuronal synapses), and the discrepancy in body build in the two disorders which is similar to that between early- and late-maturing individuals. The marked rise in manic-depressive psychoses and decline in schizophrenia, particularly the non-paranoid categories, accompanying the decline in mean pubertal age by some four years during the past hundred years are taken as evidence that manic-depressive psychosis affects early maturers and schizophrenia particularly affects late maturers. Gender differences and social differentials accord with this theory. Redundancy of neuronal synapses characterises manic-depressive psychosis, and reduced density of synapses is a characteristic of schizophrenia, whereas 'normality', with optimal synaptic density, is in between." (Saugstad LF (1989) Age at puberty and mental illness. Towards a neurodevelopmental aetiology of Kraepelin's endogenous psychoses. Br J Psychiatry 155:536-44)

“Krantz’s paper does, however, contain the germ of a much more general and useful idea, namely that there may have been a definite stage in individual brain development, correlated no doubt with brain size, but not necessarily at all closely, at which symbolic thought and speech became possible, and that this stage has receded, in the course of evolution, from the age of puberty or even later to some 13 years before puberty. ... There is, however, one feature of Krantz’z more mechanistic approach that may have a highly significant psychological correlate. If indeed the age of onset of speech in the individual has receded, pari passu with his brain size and development, from near the age of puberty to that on infancy, this might be related to the almost simultaneous onset in the modern human infant of symbolic speech and thought, on the one hand, and the symbolic rehearsal of sexual development, on the other.” (Mourant AE (1973) The evolution of brain size, speech, and psychosexual development. Current Anthropology 14: 30)

"For instance, maturation of Piagetian stages occurs much sooner in children with higher IQ's. In turn, mental age shows developmental stages that agree with those found in the brain itself. Considering the delayed Piagetian pattern of our young juveniles compared to ape juveniles (shown above) and all the evidence for hypermorphosis of brain growth is general, it seems reasonable to state that humans are peramorphic in behavior, not paedomorphic." (McKinney, M.L. & McNamara, K.J (1990) Heterochrony: The Evolution of Ontegeny: Plenum Press, New York p. 311)

"In humans the first (sensorimotor) period occurs during the first 2 years or so of life. The mental learning achievements at this time can be subdivided into six series (see Parker and Gibson, 1979, for fuller discussion): sensorimotor intelligence, space, time, casuality, imitation, and object concept. Each series in turn undergoes a six-stage sequence of development. Of extreme interest to the heterochronic perspective is that when we observe other primates, we find that they go through each of the same six behavioral series, but generally stop short in the development of that series, at an earlier stage than us. Because the truncation is associated with earlier cessation of mental development, they are "progenetic" to us, or more correctly in phylogenetic terms, we are hypermorphic to them. Moreover, the more "advanced" the primate, themore hypermorphic it generally is in serial development (see Fig. 7-7). Thus, studies on prosimians (Jolly, 1964; Parker and Gibson, 1979) showed that lorises and lemurs have reflex and grasping and simple manipulations typical of the first two stages of sensorimotor intelligence but show no evidence ofthe fourth and fifth stages of object concept. Nor in fact did they show any sign to object manipulation abilities appropriate for the last three in these stages of any of the other sensorimotor series (Box, 1984). Monkeys are more advanced in these behaviors but not as much as the apes. The stump-tailed macaque, unlike the prosimians, completed the last stage of the object concept series (an object is shown and then hidden) and got up to the fourth stage of the sensorimotor series (e.g., pulling things apart). However, they did not show tool-use or imitative behavior characteristic of the most advanced stages. For example, they never reached the last two stages on the spatial and causality series such as placing objects in other objects. Nor did they "experiment" with new objects characteristic of the fifth stage of sensorimotor intelligence. Chimpanzees and gorillas also complete the object concept series but go further in the space, causality, and imitation serier (Parker, 1977a,b). As is well known, chimpanzees use tools." (McKinney, M.L. & McNamara, K.J (1990) Heterochrony: The Evolution of Ontegeny: Plenum Press, New York p. 306-7)

"Piaget (1951) noticed that several behaviors that depend on representative capacities are acquired at about the same time: the imitation of absent models, pretend play, using words symbolically, and recognising pictures as representations of objects." (Annett, Marian (1985) Left, Right, Hand and Brain: The Right Shift Theory London: Lawrence Erlbaum pp. 120)

"In reality, the child has no imagination, and what we ascribe to him as such is no more than a lack of coherence, and still more, subjective assimulation, as is shown by his transpositions." (Piaget, J. (1962) Play, Dreams, and Imitation in Childhood: Norton, New York p. 131)

"Moreover, research into the notion of order shows that the child of four to six, although unable to tell a story verbally in the right order, or reconstruct at will a sequence of events, can intuitively arrange in order a set of coloured beads, which the child of three cannot do." (Piaget, J. (1962) Play, Dreams, and Imitation in Childhood: Norton, New York p. 136)

"Just as the symbol replaces mere practice as soon as thought makes its appearance, so the rule replaces the symbol and integrates practice as soon as certain social relationships are formed, and the question is to discover these relationships." (Piaget, J. (1962) Play, Dreams, and Imitation in Childhood: Norton, New York p. 142)

"The three essential points in Stanley Hall's thesis are well-known: games follow one another at relatively constant age stages, determined by the content of the ludic activities: the content corresponds to ancestral activities which have followed one another in the same order in the course of human evolution: the function of children's play is to liberate the species from these residues, at the same time hastening its development towards higher stages (hence the famous comparison between play and the todpole's tail). (Piaget, J. (1962) Play, Dreams, and Imitation in Childhood: Norton, New York p. 156)

"But in spite of the Freudians, for whom such symbols exist as early as the age of two months, and in spite of K. Groos, who sees make-believe in all practice play, in our opinion there cannot be symbolism, consciousness of make-believe, before there is representation, which begins and gradually develops at the beginning of the second year, when sensory-motor assimilation becomes mental assimilation through differentiation between signifier and signified. When J. pretended to be asleep, holding a corner of the sheet and bending her head, the sensory-motor schema thus set in motion resulted in more than mere exercise, since it served to evoke a past situation, and the corner of the sheet became a conscious a conscious substitute for the absent pillow. With the projection of such "symbolic schemas" on to other objects, the way is clear for the assimulation of any one object to another, since any object can be a make-believe substitute for any other." (Piaget, J. (1962) Play, Dreams, and Imitation in Childhood: Norton, New York p. 167)

"The unconscious is everywhere, and there is an intellectual as well as an affective unconscious. This means that it does not exist as a "region," and that the difference between consciousness and the unconscious is only a matter of gradation or degree of reflection." (Piaget, J. (1962) Play, Dreams, and Imitation in Childhood: Norton, New York p. 172)

"Thus one day T. used "daddy" to refer to any men who were fifteen to twenty yards away and who were walking (as distinct from those who were motionless) and only later included all men like his father in this class. Moreover, "mommy" and "daddy" may be used to emphasise some action done in an unusual way by the parents. It is clear that these words, for from denoting merely singular classes and being proper names, as the statistics of Mrs. Buhler (Kindheit u. Jugend, pp. 149-150) suggest, really represent complex schemas of actions, either related to the subject or partly objective." (Piaget, J. (1962) Play, Dreams, and Imitation in Childhood: Norton, New York p. 219)

"These two characteristics, absence of individual identity and of general class, are in reality one and the same. It is because a stable general class does not exist, that the individual elements, not being asembled within the framework of a real whole, partake directly of one another without permanent individuality, and it is the lack of individuality in the parts which prevents the whole from becoming an inclusive class. Thus, as it is still half-way between the individual and the general, the child's preconcept constitutes a kind of "participation" (in the sense of Levy-Bruhl), this relationship being defined as follows: absence of inclusion of the elements in a whole, and direct identification of the partial elements one with another, without the intermediary of the whole. To take an example from earlier observations we made, a shadow thrown on a table was thought to come directly from the shadow of trees, without going through the general class of shadows which is defined by their law of formation." (Piaget, J. (1962) Play, Dreams, and Imitation in Childhood: Norton, New York p. 227)

"We have tried to show elsewhere that the shemas of sensory-motor intelligence constitute the functional equivalent of concepts and relations, and that sensory-motor assimilation is a kind of practical judgment, the co-ordination of schemas one with another being thus equivalent to sensory-motor reasoning. But obviously it is only a question of functional equivalence, which in no way entails structural identity. Between sensory-motor intelligence and conceptual intelligence, there are, in fact, four fundamental differences, which indicate how far the former falls short of being logical thought. 1. The connections established by sensory-motor intelligence link only succesive perceptions and movements, without an overall representation dominating the states, distinct in time, of the actions thus organised, and placing them simultaneously in a complete table. For instance, the system of displacement involved in a behavior such as the search for a lost object may be co-ordinated in a kind of experimental "group," but the only relationship is between successive movements and there is no representation of the system as a whole. Sensory-motor intelligence thus fuctions like a slow motion film, representing one static image after another instead of achieving a fusion of the images. 2. Consequently, sensory-motor intelligence aims at success and not at truth; it finds its satisfaction in the achievement of the practical aim pursued, and not in recognition (classification or seriation) or explanation. It is an intelligence which is only "lived" (an intelligence of situations, to use Wallon's expression) and not thought. 3. As it field is defined by the use of perceptual and motor tools, it acts only on real objects as such, on their perceptual indices and motor signals, and not on the signs, symbols and schemas related to them (concepts and representative schemas). 4. It is thus essentially individual, and lacks the social dimensions resulting from the use of signs." (Piaget, J. (1962) Play, Dreams, and Imitation in Childhood: Norton, New York p. 239)

"It is clear from these examples that names begin by being localised in objects, dreams in the bedroom, and thought in the voice, and that it is only at the age of about seven that mental activity is grasped as being internal. It is at the age when symbolism is at its height that names and dreams are projecting into external reality, and it is when symbolism is declining, and when true concepts are taking the place of imaged preconcepts, that thought leads to an awareness sufficient to allow of relative, internal localisation." (Piaget, J. (1962) Play, Dreams, and Imitation in Childhood: Norton, New York p. 257)

"It is in relation to these three notions that both the continuity and the opposition between sensory-motor schemas and representation are most clearly visible. As we saw in La Construction du Reel Chez l'Enfant, a vast spatio-temporal construction takes place in the mind of the child between birth and the last stage in the development of sensory-motor intelligence, i.e., during the first eighteen months. Starting from a world containing neither objects nor permanent substances, with various sensorial spaces centred on the child's own body, a world in which there is no time other than the moment being experienced by the child, the construction results in a universe of permanent objects contituting a single practicle space that is relatively decentred (in that it includes the child's own body as one element among many), and evolving in temporal series that allow of practical reconstruction and anticipation." (Piaget, J. (1962) Play, Dreams, and Imitation in Childhood: Norton, New York p. 262)

"Between about 0;8 and 1;0 the child begins to look for objects that vanish, i.e., he attributes some measure of permanent substance to them, but without allowing for their visible displacement, as if they were linked with a particular situation. When he is between 1;1 and 1;6, however, objects come to have individual substance that is preserved in spite of displacement and makes their reappearance possible." (Piaget, J. (1962) Play, Dreams, and Imitation in Childhood: Norton, New York p. 267)