COGNITIVE DEVELOPMENT

‘Cognition’ is a broad term encompassing reasoning abilities, knowledge and memory. The study of cognitive processes is fundamental to many topics in psychology. Developmental psychologists are interested in the origins and course of cognitive capacities, with a great deal of interest therefore being paid to their manifestation in infancy. Infants react to information provided by their senses by attempting to organize experience, make sense of phenomena, and anticipate events or outcomes. In fact, when we examine what infants do with the data they obtain from the world, we find that they appear to behave in much the same way as scientists. They try things out, they collect more evidence (by exploring and by trial and error), and they start to develop theories. The idea that babies, without the benefit of a formal education and not even able to speak, could generate theories about the world seems surprising on first consideration. Yet, one of the most influential psychologists of t he last century has argued exactly this, and his account has attracted enormous interest from other psychologists and educators. The sensorimotor stage of development Jean Piaget (1896 –1980), a Swiss psychologist, developed a model of cognitive development which holds that children’s thinking progresses through a series of orderly stages. According to Piaget, each stage reflects qualitative differences in the way the child understands and acts upon the world relative to its status at another developmental phase. Later in this chapter, and in the next, we will consider the other stages of Piagetian development, but for the moment we will focus on the first, sensorimotor [sensorimotor stage the first stage of cognitive development, according to Piaget, extending from birth to approximately two years, when the child constructs an elementary understanding of the world and thought is tied closely to physical or sensory activity] stage, which Piaget described as extending from birth to approximately two years. Piaget saw the child in this stage as acting to learn about itself and its relations to the environment. A key emphasis here is on the child’s actions. Piaget believed that children learn by doing, and that they advance their understanding by testing what they know to its limits (much as scientists do). Piaget argued that initially infants lack the ability to reflect consciously on their experiences, but they do have a set of reflexive capacities (including those that we considered earlier in this chapter) that cause them to react to environmental stimuli. These are simple, but important processes. If something is placed near an infant’s mouth, she will attempt to suck it. If you place your finger in a baby’s hand, she will grasp it. The baby can also make vocal sounds. All of these actions can be repeated, and babies do indeed repeat them, generally becoming more proficient with practice. The actions can also be modified to cope with new experiences. As well as grasping your finger, infants will respond similarly if you place a rattle o toy in their hand, or if they find a bar on the side of their crib. In this way, the infant develops action based schemes – organized patterns of behaviour that she comes to rely on in dealing with her world. Before long, the infant discovers interesting new consequences from her initially reflexive schemes. Grasping some objects (toys) causes the infant to produce interesting noises (squeaks or music). Sometimes a shake (of a rattle) or a push (of a mobile) yields other appealing sounds or movements. The infant repeats the action, and the same thing happens. In these ways, babies are learning about cause–effect relations, and their own ability to influence the world. Infants show delight as they learn how to control things, and repeat the actions frequently – until it becomes too easy, and then they seek new challenges.


Jean Piaget (1896–1980) was one of the most influential psychologists of the twentieth century. Born in Neuchâtel, Switzerland, in 1896, he published his first paper (a short note on an albino sparrow) at the age of 11. He studied zoology at the University of Neuchâtel, but his interests in biological change and the origins of knowledge led him into psychology. In 1920, he moved to the Alfred Binet laboratory in Paris, where he undertook research on intelligence testing, leading to a fascination with the reasons that children suggested for their answers to standard test items. This resulted in some 60 years’ ingenious research into the development of children’s thinking. In 1955, Piaget established the International Centre for Genetic Epistemology in Geneva.



Object permanence [object permanence understanding that an object continues to exist even when it cannot be seen or touched] In the course of all this seemingly playful activity, infants are learning a great deal. But at any one stage, there are limits to what they know. For example, in the first few months of life, although babies get better at manipulating objects, the stability of objects in their lives is generally beyond their control – things (such as toys) come and go. Piaget maintained that very young infants have no conception of the durability of objects: according to Piaget, at this age, while something is within reach or sight, it exists, but ‘out of sight is out of mind’. The notion that an object can continue to exist even when we cannot see it is termed object permanence. Piaget believed that this is a relatively late achievement of the sensorimotor period (around nine months). Other developments during this sensorimotor stage of development include greater experimentation with the things the infant can do with objects, learning to use objects as tools, and systematically copying others’ behaviour to achieve new skills. Piaget challenged Piaget’s descriptions and explanations of infant activities are persuasive and continue to have a great deal of influence upon developmental psychology. But they have been challenged. Subsequent research has demonstrated that Piaget tended to underestimate infants’ abilities. For example, several studies have shown that object permanence is available earlier than Piaget believed to be the case. Hood and Willatts (1986) presented five-month-olds with objects within their reaching distance. The researchers turned off the lights, removed the objects and released the babies’ arms. The infants tended to reach towards the place where the object had been located before the lights went out, indicating that the infants could maintain a representation not only of the object but also of its location. Some of the perceptual abilities that have been described in infants (e.g. face perception, discrimination among speech sounds) also present a problem for Piaget’s theory. One of his core assumptions was that children have only a limited amount of innate knowledge and that they construct their understanding of the world through active and general developmental processes. By ‘general’, Piaget has in mind that changes are preceding at roughly the same pace in most areas of the child’s knowledge. There is a broad sweep improvement going on in mental capacities that is reflected in different areas of understanding roughly simultaneously. This seems to make sense: after all, we know that babies can do a lot more at 15 months than they can at five months. But if some abilities are ‘built in’, then considerably more is innate than Piaget maintains. As well as face perception and speech discrimination, there is also intriguing evidence that infants as young as five months can add and subtract with small numbers, leading to speculation that humans are born with the capacity to perform simple arithmetical operations (Wynn, 1992). There is little basis for explaining the development of these abilities by the outcome of general changes resulting from continuous activity. Furthermore, whether these abilities are innate or not, they seem to develop at different times. Some emerge quite early, such as face perception, which is well developed (though not complete) in the preschooler. Others take a bit longer, such as language, which starts during the first year but progresses into middle childhood. Arithmetic ability is still developing into the teens. Maybe, then, Piaget is mistaken to conceive of development as one all-embracing general process, with changes occurring at about the same time across all areas of knowledge. On the basis of observations like these, some psychologists believe that it may be better to regard the growth of knowledge as involving specific domains, each with its own developmental course (Keil, 1999). This debate – between those who (like Piaget) favour domaingeneral theories and those who favour domain-specific theories – highlights fundamental questions about the nature of the human mind and is central to much of contemporary developmental psychology (see Garton, 2004; Hatano & Inagaki, 2000). Piaget made a key contribution to psychology by highlighting the importance of the infant’s actions as a source of development. Piaget was a constructivist: [constructivist theorist who attributes the acquisition of knowledge to the active processes of the learner, building on increasingly complex representations of reality] he saw development as a kind of self-directed building process, in which the individual constructs schemes of action, applies them repeatedly until reaching their limits, and then improves upon them in the light of new discoveries. Although details of his theory have been challenged, in the light of Piaget’s contributions most researchers agree that infants are active cognitive beings, not the blank slates supposed by the early behaviourists.

Motor development

The neonate has several reflexes (automatic physical responses to external stimulation), including: n the rooting reflex – a tendency to orient the head and mouth towards an object touching the face; n the sucking reflex – a tendency to suck on objects placed in the mouth; n the grasping reflex – a response to stimuli (such as a finger) placed in the open palm; n the Moro reflex – a reaction to sudden loss of support to the neck and head in which the baby thrusts out his arms and legs as if striving for support; and n the stepping reflex – the infant attempts to take ‘steps’ if held upright with feet touching a surface. Some of these reflexes have important benefits. For example, the rooting and sucking reflexes ensure that the normal infant will respond to contact with the mother’s breast by seeking out the nipple and feeding (Widstrom & Thingstrom, 1993). Although biology provides the reflexes, early experience is important insofar as it can affect their manifestation. In one study, neonates who were separated from the mother during the first hour after birth were less likely to demonstrate correct sucking techniques, and babies whose mothers were sedated during the birth did not suck at all during the first two hours (Righard & Alade, 1990).

Hearing, taste and smell

The infant exploits all her senses as she learns about and reacts to her world. Hearing, although not fully developed at birth, is well developed at this stage, enabling young infants to discriminate among sounds that vary in volume, duration and repetitiveness, and to organize their perception of and responses to the spatial environment (Kellman & Arterberry, 1998). So when exposed to the ‘approach’ of an illusory object (a sound increasing in volume), quite young infants lean away as the noise gets louder (Freiberg, Tually & Crassini, 2001). Perhaps one of the starkest pieces of evidence against the ‘empty vessel’ theory of human nature comes from the infant’s discrimination among tastes (Mennella & Beauchamp, 1997). Babies are not passive when it comes to food and drink, and display clear preferences. Their sucking rate increases for sweet liquids, but decreases for salty or bitter liquids (Crook, 1978). They show by their facial or vocal expressions whether they like or dislike a particular taste, and will protest vigorously if offered something they find unpalatable (Blass, 1997). These preferences are by no means arbitrary and may well have survival value. Infants do not have conscious nutritional information to help them decide whether a foodstuff is good or bad for them, but they know what they like. For example, alcohol is potentially harmful to infants, and research suggests that they would prefer not to drink it. Mennella and Beauchamp (1994) compared babies’ consumption of breast milk when their mothers had been drinking either alcoholic beer or non-alcoholic beer. In the alcohol condition, the babies drank significantly less milk. Babies’ taste preferences can also be exploited by adults – certain tastes, such as milk or sweetened drinks, help to calm down a crying infant (Blass, 1997). Infants react to smells in similar ways. Their facial expressions or head orientations reveal whether they find a smell pleasant or unpleasant (Soussignan, 1997). Again, the sensory preferences may have survival value. For instance, there is evidence that infants are attracted to the smell of amniotic fluid and to milk (Marlier, Schaal & Soussignan, 1998).

Vision

The human infant’s visual system provides a crucial means of exploring and reacting to the environment (Slater & Johnson, 1998). Although newborns’ visual acuity is less than perfect, they can certainly take in a great deal of visual information, and they soon show signs of pursuing it actively (von Hofsten, 2001). If you hold an object about 30 cm from a neonate’s face, he can focus on it and may track it if you move it slowly from side to side. At this stage, the baby’s visual attention is likely to be concentrated on the object’s edges, but over the next few weeks he will begin to explore its whole surface (Aslin, 1987). Within the first couple of months, infants can switch visual attention from objects immediately in front of them to events (such as a light flashing) on the periphery of their visual field (Maurer & Lewis, 1998). By three or four months, they are able to organize complex visual configurations, distinguishing between intersecting forms (Quinn, Brown & Streppa, 1998) and exploiting illusory contours to perceive boundaries and depth ( Johnson & Aslin, 1998). Babies appear to be particularly interested in faces, which hold their attention and elicit smiles (Fantz, 1961). Some evidence indicates that even neonates less than one hour old prefer illustrations of a human face to other patterns of similar complexity, and they prefer regularly organized representations to pictures that jumble the facial features ( Johnson & Morton, 1991). Such early preferences raise the serious (if controversial) possibility that infants have innate ‘face detectors’, which direct their attention to this aspect of the visual environment (Slater et al., 2000).

PHYSICAL AND SENSORY DEVELOPMENT

We experience the world via our senses, and our everyday negotiation of the environment depends upon our skills in exploiting and coordinating the information they provide. But these abilities did not emerge suddenly. We have enjoyed the benefits of sensory equipment since we first came into the world (and maybe before). Babies have a rich array of perceptual and physical capacities, which enable them to engage with the world in more complex ways than was once believed. Some of these capacities seem to be present at birth, some develop rapidly during the first year or so, and some vary according to the opportunities for exercising them.

INFANCY

The influential early behaviourist John B. Watson once proclaimed: ‘Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I’ll guarantee to take any one at random and train him to become any type of specialist I might select – doctor, lawyer, artist, merchant-chief, and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocation, and race of his ancestors’ (1924, p. 82). But are people really empty vessels to be filled up or shaped by their environments? People often think of infants as helpless and malleable. Clearly, in some quite fundamental respects, they are dependent upon others. They are unable to meet their own physical needs (feeding, cleansing, finding shelter) or to move around or engage in discussion. Observations such as these have led to a traditional belief that the child is shaped by experience. The strongest expressions of this assumption have been provided by behaviouristic psychologists, like Watson, who assert that the child is the product of its reinforcement history. However, more recent research by developmental psychologists has radically altered our understanding, and the traditional notion of babies as empty vessels waiting to be filled by experience has now been abandoned. In this section, we will examine an array of evidence pointing to the remarkable complexity and competencies of the normal human infant.

TOP-DOWN MECHANISMS

Perceptual processes that are concerned solely with sensory input are often called ‘bottom-up’. But perception also depends on ‘top-down’ processes, which reflect our personal goals and past experience. ‘Bottom-up’ processes are governed only by information from the retinal image. ‘Top-down’ is a vaguer concept, since it is not clear where the ‘top’ of the visual pathway is or what it does. But ‘top-down’ certainly involves the voluntary components of perception, such as moving the eyes. For example, when we discussed conjunction search, earlier in the chapter, remember the observer moving their attention around a display to search for a target (such as a tilted red line or a blue Ford car). This kind of deployment of attention to locate a target is generated internally rather than externally, and is therefore considered to be ‘topdown’ (in contrast to, say, the sudden appearance of an object in peripheral vision, which will capture the observer’s attention and gaze automatically). Additional support for this dea comes from studies showing that selective adaptation phenomena can be affected by changes in attention. As we saw earlier in this chapter, adaptation can occur at relatively early stages of visual processing, perhaps including V1. A major finding of the anatomical studies we discussed earlier, in the section Serial versus parallel theories of perception, is that almost all the connections between the visual areas of cortex (e.g. figure 8.12) are reciprocal. In other words, information passes not only serially up the system but also backwards, from ‘higher’ regions, down towards (but not reaching) the sense organs. For example, just as area V1 projects to V2, so area V2 also sends messages to V1. How might these reverse connections mediate the perceptual functions that involve top-down influences? The idea that attention to different aspects of the world is mediated by top-down connections is supported by several recent brain scanning studies indicating that relevant regions of the visual cortices alter heir activity levels when the person is attending (Kastner & Ungerleider, 2000; Martínez et al., 2001). The idea is that ‘higher’ parts of the brain decide what to concentrate on, causing messages to be sent back down to prime the relevant parts of the visual cortex. This facilitates cell responses to expected stimuli and improves cell selectivity (tuning), so there are now increased differences in the output of a cell when it is tested with its preferred and some non-preferred stimuli (Dosher & Lu, 2000; Lee et al., 1999; Olson et al., 2001). It has been further noted that even the LGN can be affected when attention changes (O’Connor et al., 2002). Another idea is that perceptual learning, recognition and recall depend upon these top-down connections. The hippocampus is important in laying down new long-term memories. Feedback connections from the hippocampus to the cortex, and within the cortex, appear to be responsible for building these new memories into the fabric of the cortex (Rols, 1990; Mishkin, 1993; Squire & Zola, 1996). Physiological studies of cells in area V1 of the monkey support theories (Gregory, 1970; Rock, 1983) that memory for objects interacts with the early, bottom-up stages of sensory processing. So the selectivities of the cells in V1 change in the first few hundred milliseconds after a stimulus is presented (Lamme & Roelfsema, 2000; Lee et al., 1998). As activity reaches the ‘higher’ visual centres, it activates neural feedback, which reaches V1 after a delay. The latency of this feedback is caused by the limited conduction velocity of the messages along the nerve axons and by the time taken to process the information in the ‘higher’ cortical areas. Recent studies of practice on perceptual tasks indicate that the learning triggered by these feedback projections is so specific for the relevant stimuli that it can only be taking place in the ‘early’ processing areas of the visual cortex (Ahissar & Hochstein, 2000; Fahle, 1994; Lee et al., 2002; Sowden et al., 2002). Moreover, scans taken of observers’ brains when they are recalling or imagining a visual scene show activation of the same early areas of visual cortex that are activated during stimulus presentation itself (Kosslyn et al., 1993; Le Bihan et al., 1993). As indicated by this discussion, the old division between sensory and cognitive processing by early and higher neural centres has recently been replaced by a new dynamic model. Incoming sensory information interacts with task-relevant knowledge, acquired during the development of the individual concerned, and has been built into the neural network structures in several different cortical areas. Acting together, these influences create an integrated and dynamic representation of the relevant aspects of the environment (e.g. Friston & Price, 2001; Hochstein & Ahissar, 2002; Lamme & Roelfsema, 2000; Schroeder et al., 2001).