Motivation and emotion/Book/2013/Developmental changes in motivation

Developmental changes in motivation: How does human motivation change during human development across the life-cycle?

Overview

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Motivation is something that we have all felt and experienced throughout our lives, it changes as we age and directs our attention. What motivates you to read this self help book chapter? Is it because you enjoy reading about psychology for personal interest? Or are you reading it for some other purpose? How will people with different motivations behave differently? Motivations we experience vary in their strength, direction, and level of importance to us. The understanding of how these changes transit though our life cycle is an integral part of facilitating personal development, increasing our motivational efficiency and drive to succeed.

Diversity in motivation between individuals can be attributable to differences between individuals, cultures, economic status, environments, generations, and development. The concept that our motivations change as we develop and grow with age is widely supported and studied within developmental psychology. Motivational changes during the life-span is a relatively new concept with developmental theories of psychology emerging in the 1940s. The theories spanned across the varied main fields of psychology including the social, cognitive and ecological domains[1]. Yet there are three common developmental differences between all of the psychological fields, those being the nature versus nurture debate, passive or active development, and whether the process is a continuous or a stage like transition.

Whilst at first glance motivational development appears complex and hard to understand, this chapter will help unravel the complexity of it. This chapter aims to help you gain a better understanding of the developmental changes we undertake through our lifespan and help you life a more effective motivation life.

Definitions

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Motivation is an inner personal drive and desire that we feel. It is motivation that determines our goal-directed behaviour. The strength and direction of behaviour is determined by our need to survive, our thoughts, our emotions, and the effect of external events. The motivation brewed from within an individual is termed intrinsic motivation, whilst the external or out-of-the-body creations of motivation are extrinsic motivations [2]. The direction of motivation can be in an avoidance or an approach trajectory. Whilst at any single time an individual can hold many different motivations, the strongest felt motivation will always be acted on first. The motivations we hold can be influenced by the expected and non-expected outcomes such as rewards or punishments, how able we believe we are to perform the task, and the what type of goal it is being either task- or mastery-focused. Motivation is then measured by brain activations, how engaged we are, our attentional focus, and the behaviour itself[citation needed]. Needs are the physiological, psychological and social components that allow humans to survive and grow.

History

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Human development is dynamic. There is no single accepted theory about how human motivation develops through life. However, a common concept that theories agree on is that “development is a series of progressive changes that individuals characteristically show as they progress in time through the human life cycle” [3]. Due to the lack of a common theoretical consensus there are a number of theories that work together each specialising in a singular aspect of motivation. Due to this, there are a plethora of theories that attempt to define the influential constructs of development most of which focus on the proximal influences of learning, thinking and identifying how information is processed, as well as behavioural, emotional, social interactions with both parents and the child’s environment. Other theories identify the distal or sociohistorical influences on society through evolution as the defining factor; these constructs include values and tools outlining a phylogenetic approach.

Whilst the theories of human development maintain varied influences, the pioneers of the area and their classical founding theories can be divided into two main frameworks to understand the developmental principles[1].

The mechanistic approach explains development as a passive process in which people are like machines who possess computer-like information processing skills that are performed with continual gradual stages of development. Pioneers of this framework include Pavlov (1849-1936) behavioural, Skinner (1904-1980) behavioural/reinforcement theory and Bandura (1925-) social learning.

The organismic approach explains development as an active process in which people are viewed as a whole and not deconstructed in to smaller parts. This process unfolds through non-continuous stages of development. Pioneers of this framework include Piaget (1896-1980) cognitive, Freud (1856-1939) psychoanalytic, and Maslow (1908-1970) humanistic.

These pioneering theories have been the fundamental platform for the current views, frameworks and beliefs held by contemporary developmental psychologists. Though there are still three common theoretical differences.

Developmental motivation common theoretical differences

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There are three theoretical issues that current and past developmental scientists alike hold conflicting views about:

  1. Heredity (nature) vs. environment (nurture)- the nature theorists hold that innate traits and their characteristics are inherited from one's biological parents and that this genetically determines an individual's development. Conversely the nurture theorists hold that environmental influences, both before and after birth, are most influential on development.
  2. Development is an active vs passive process – The mechanistic model is based on the machine metaphor that views development as a passive, predictable response to internal and external stimuli. The organismic model views development as internally initiated by an active person, or organism, and as occurring in a universal sequence of qualitatively different stages of maturation.
  3. Is development continuous or does it occur in stages? Mechanistic models mostly agree that development is a continuous process whilst organismic models mostly agree that development occurs in identifiable, defined qualitative stages.

Current theories

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Contemporary theories of development and motivation are bidirectional, recognising a dynamic system of interactions between the organism and the environment. However, the issue of isolating the key determining factor of behaviour and motivational changes is, as it was for the pioneers, still undecided. Current theories are shaped from a focus on a variety of principles of both internal and external causes. Internal principles consist of biological and neurological factors, needs, cognitions, and emotions, whilst external principles include ecological, environmental and social interactions. Hence, the current theories of motivation, from a developmental psychology perspective, are numerous. This chapter will use a contemporary macro theory, Self determination theory [2], and focus on the hierarchy of sources for motivation (needs, cognitions, emotions) and a cognitive neuroscience perspective to help you understand how human motivation changes during human development across the life cycle, all in a bid to help you live a more effective motivational life.

The how, what, where, when and why's: The cognitive foundation of motivation

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Development - A cognitive neuroscience perspective

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We all know that as we transit through time from birth we age, mature and develop. We gain the ability to focus attention, develop and maintain relationships, operate and remember tools of the era along with perform executive cognitive functioning. The areas of development that play an integral part in constructing motivation include cognitive development, the development of our senses, and the dynamics of our environmental niche construction [4]. Even before birth the human brain has undergone a series of processes, manufacturing and moving individual nerve cells allowing specialised characterises to form, hence developmental differences can arise ever prior birth. At birth we have more neurons than we need therefore post birth the brain is relentlessly remodelled. The modelling occurs as synaptic pruning, cell death, and the proportions of grey and white matter are changed and adapted during development. As a human baby enters the world it is equip with a collection of innate survival skills. These skills are not learnt behaviour they are receiving (sensory) and transmitting (crying) information systems and reflexes. These abilities allow the neonate to communicate and survive. The reflexes a child is born with are pre wired responses of how to react to certain stimuli in order to survive and facilitate learning [5] The strength and presence of a reflex determines the quantity of neural development a neonate has (APGAR test). Some reflexes are permanent whilst the remainder disappear throughout the first year of life or change to become chosen or voluntary behaviours [1].Hence, reflexes are the initial building blocks of the neural and cognitive pathways used throughout life. Human development facilitates the growth and increase of neural tissue as the infant interacts with their surroundings, the people and objects in it the neurobiological system is reinforced and refined. With this advancement in learning and exposure to the world our innate reflexes dissipate and our learnt behaviour together with cognitive development becomes the primary source of our actions. The transition occurs by synaptic connections and mylination increaseing efficiency of the message pathways. As we all know babies have smaller brains than adults, yet this is not attributed by the amount of neurons we have at birth. The size difference of the brain from child to adult is simply not due to the amount of neurons rather the size of neuron and the amount of mylination and synapses it possesses [6]. Cognitive development outlines the neurological frame work and the evolutionary adaptations across the life span the brain is subjected to. Conceptual frameworks of thought mature through childhood with the distinction between logic and abstract thought, reality and appearance distinction, reversibility and perception all occurring as an individual matures [1]. The cognitive neurological interactions that shape the development of memory, the ability to reason and see others perspective and not just the ego centric view are also directly influenced by an individual’s transition of development [7].

 
Brain maturation ages 5-20

The development, maturation and strengthening of these pathways continues well in to adolescence [7]. Weaker top-down modulation from the left inferior frontal gyrus in children. Neuro Image , 33, 991-998.</ref>. Some studies identifying specific brain regions to maintain developmental differences until early adulthood [8], [9]. These studies show the difference between adolescents and adults behaviour is the level of enhancement to the prefrontal neural network construction, identifying that the structures are already in place allowing adolescences to behave like adults sometimes, yet the neural fine-tuning has not yet occurred and hence revealing the true teen behaviour returns [10]. Other studies highlight that during adolescence increases in sensation seeking and novelty behaviour occur, and the adaptive benefits from these result in motivating adolescents to explore and experience new social relationships and environments, warming them to the expectations and events of adult life [11], [12].However, most of the developmental theories do agree that during the years of adolescence individuals exhibit significantly higher amounts of impulsive risk taking behaviour, reward sensitivity, depressive disorders and reduced punishment sensitivity and hence express unique timing and pattern of the neural activation code and recruitment, specifically in the prefrontal regions of the brain [8]. Thus, developmental cognitive neuroscience and its adaptive capacity is a highly influential component of motivation.

 
Human brain development 1wk-3mo-1yr-2yr-10yr-T1W-MRI


Individual differences in motivation have been attributed to the maternal development influences prior birth such as birth weight, premature birth [13],and exposure to teratogens all of which have been shown to interfere and cause negative outcomes to child development [5]. Other studies have positively linked IQ and the breast feeding routines followed by the [14]. However, the focus of this chapter will be addressing the cognitive development post partum. Individual cognitive development after birth and throughout the life span is modulated by our ability to absorb, understand and organise information about our surroundings and how we are positioned in them, therefore the successful development of our senses is imperative. These traits allow us to perceive our world, before further cognitive processes elect how to react and behave to any given stimuli.

Development of senses

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The development of the senses all are primary information receiving systems that determine how we comprehend our surroundings, therefore they are influential characteristics for the development of behaviour and motivation. These are all abilities that if an individual has an abstract or unusual level of the said characteristic it will affect their behaviour permanently. Sight whilst constructed in the womb and is evident yet of poor quality at birth and it develops rapidly after birth (Fantz, 1963) and by the age of seven to eight months vision is close to adult levels [1] Vision has been shown to affect development by Fantz's body of research, young infants can recognise imitate their mother and determine differences between human faces and other circular forms [15]. Perception has also been shown to be a developmental milestone cognitively and in Piaget’s well known object permanence and conservation tasks [1], [16].An individual’s sense of smell develops prior birth, a study has shown that babies in the first week can discriminate between the scent of their mother compared to other nursing mothers and with this correlation they behaviour can be quickly modified [17].Thus if debilitated it can have instrumental effects on the development of an individual. Our sense of taste and preference of sweet over all others tastes has been shown to arise before birth, whilst taste preference is known to be influenced by the mothers diet [18] developmentally this can be responsible for obesity later in life. Hearing is also a sense that is developed prior birth and it improves during the first year of life. Some studies have identified language preference of native tongue and ‘motherese’ tone and pitch is present from an early age [19]. Whilst a newborn prefers female over male voices [5], an interesting study revealed that infants not only recognise their mothers voice, yet the infant is capable of modifying and changing their sucking behaviour to hear their mothers speech [19]. Thus hearing development has a strong influence on infant behaviour. The sense of touch has been identified to help regulate heart rate and respiratory rate of premature babies [20]. Touch also has been linked to bonding and the release of hormones, both in mother and child [11].Evidence shows that development of our senses is a vital component of life, influencing how information is received. Once received the information gathered by our senses is then deciphered, categorised and transmitted by our neurological and cognitive systems.

Brain regions and Chemicals

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Medical neuroimaging studies of fMRI and PET scans have enabled deeper investigations of the brain. These studies have lead to the discovery of mirror neurons which has shed some light on the development of imitating behaviour from a neurological standpoint, outlining the observation/execution neurological relationship and how it affects goal directed behaviour [21]. These imaging advancements have depicted conclusive neurological maps of the brain, presenting the specific areas of activation for behaviour. The brain regions that are activated for behaviour are primarily located in the frontal lobes. With the areas responsible for the cognitive control of behaviour including the prefrontal cortex, striatum, parietal cortices, thalamus, cerebellum, and brainstem all to enable a top-down control of behaviour [22]. The Sub cortical structures help determine behaviour as they are involved with associating if an experience is pleasant or unpleasant. The Prefrontal cortex and striatum also function to process rewards [10].The ability to remember is a product of the amygdala and hippocampus working together and the executive functioning of an individual is a process the prefrontal cortex directs [8].

Synaptic Transmission ans Neural Development

Neurotransmitters are messenger chemicals that communicate and transmit signals between the neurons of the brain and central nervous system. The neurotransmitter that has a direct influence on motivation is dopamine. This neurotransmitter and the cells that make it are active when reward, incentive stimuli and positive feelings are present [10]. Dompamine is also linked strongly to maternal care and attachment [11]. The hormones that directly influence human behaviour consist of testosterone, estrogen and oxytocin. Estrogen is responsible for social emotional behaviour whilst testosterone is involved with sexual motivation and behaviour along with aggression. Oxytocin is the bonding hormone that affects an individual’s sexual behaviour, mate selection, rewards, arousal and pro social behaviour. It also has been shown to reduce social anxiety whilst falling in love, becoming a parent and breastfeeding and is released during sexual activity, affectionate behaviour and social engagement [11] .Research shows that humans have a developmentally sensitive biobehavioural system with the quantity and density of neural components in specific brain regions being susceptible and affected by rearing such as maltreatment and adversity in early life [23]; and the progression through developmental stages [11] hence giving rise to permanent modifications of motivation and behaviour.

 
Piaget's object permanence- When the object is covered it must have disappeared. http://wikis.lib.ncsu.edu/images/f/fd/Objectperm.jpg

Theories of motivation

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Stages of cognitive development theory - Piaget (1896-1980)

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Whilst this theory is not a favoured contemporary theory of cognitive development it would be unjust to go without mention of Piaget and his historical ground breaking discoveries. Piaget believed development was a process of progressive stages, building up from the previous stage in order to advance through the stages one must complete the prior stage before moving on and the sequence of stages is always the same[16]. He posited the concepts of schemas, assimilation and accommodation as crucial components of the developmental processes. Piaget’s theory of cognitive development defines specific age brackets in which a child will belong to a stage, he has been criticised for this as it is thought that he has underestimated the age paradigms. Yet the positives of his theory are noted as it questions logical thought, he defined and suggested the concepts of egocentrism, irreversibility, reality/appearance distinction, conservation and centration [1]. As illustrated in tables 1,2 and 3 Piaget not only set out four main stages of child development (table-1) he also ascertained sub stages to the sensory motor (table-2)and pre operational stages (table-3). The influence of Piaget’s work on psychology from a developmental perspective is evident in today’s contemporary theories, though not used in its entirety.


Hierarchy of needs - Maslow

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MaslowAbraham Maslow posited that behaviour is due to a system of basic needs that work together and intertwine to determine and ‘make sense of development through the lifetime and across cultures’ [24]. He focused on the entirety of the person and not just the physiological drives. The levels of hierarchy are built from lower order governing physical needs, and increase to self actualization. Maslow termed his theory as a health and growth approach to psychology [25]. Whilst he felt that human motivation maintained common characteristics across different cultures and races he also noted age related differences . Goebel & Brown [24] built from Maslow’s scale and developed the Life Motivation Scale to assess the age differences in motivation. They found significant age related motivational differences. Children have the highest physical needs and the lowest self actualisation needs, whilst love needs arise between childhood and young adulthood and adolescents have the highest esteem needs. Security needs are higher in older adults. The study also highlights sex differences as a key factor of motivation; female children had the lowest love needs than all other females. Whilst male adolescents have the lowest need for love by young adulthood males have the highest love need than all other male groups. Contradictions of Maslow’s need scale are centered around how the lower order need must be met first before progression on to higher needs, and reversals of the love and esteem levels have been noted to be more suitable. The use of the hierarchy scale suggests that “Maslow’s dominance may not be as developmentally useful as a focus on intra-need age changes” [24]

 
Table 4 Maslow's Hierarchy of Needs

Self Determination Theory - Deci & Ryan, 1991

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This contemporary framework is built from Maslow’s needs platform and identifies three key needs integrated with processes and motivation; competence, autonomy and relatedness [2]. Competence is the sense of self efficacy and the ability to problem solve and understand how to achieve a goal, relatedness being a sense of security and relationships with others, and autonomy denotes personal agency, the ability to enact, chose and control behaviour [26]. Self determination theory outlines and distinguishes between different types of motivation based on the different reasons or goals that give rise to an action[2]. The theory maintains there are significant differences in outcomes depending on the form of motivation utilized and there are different achievement beliefs that can be divided in to specific domains such as task and outcome goals, self determined and non self determined methods of motivation and the differences of extrinsic and intrinsic motivation and how it plays a significant role in constructing motivation. Self determination theory ascertains that intrinsic motivation is performed for the enjoyment of the activity and is deemed to increase performance and persistence, whilst extrinsic motivation from a source separate to the activity in order to avoid undesirable consequences is deemed to decrease such outcomes [2].A study recent study has shown age related differences in self determined extrinsic and intrinsic motivation noting a steady decrease between the age of 9 and 12, it then plateaus and increases from the age of 15, with non self determined extrinsic motivation shown to decrease until the age of 12 [27]. These results are thought to be due to a number of factors including an increase in social desirability [28] and a decrease in choice due to the increase of teacher control in a classroom [27]. Whilst these results are of a concern to parents and educators alike it has been suggested that these trends can be adjusted. Task intrinsic goals denote a lower drop in intrinsic motivation [29] and effective autonomy support by teaches and to a lesser extent mothers affects the age-motivation relationship within the intrinsic and self determined extrinsic realms [27]. Self determination theory has also denoted age related trends in motivation can be adjusted by the complexity and speed of a task which affect the level of competence and autonomy an individual experiences . This macro theory of motivation is a popular contemporary fixture in developmental psychology [26].

 
Table 5 Flow Chart of The Self-Determination Continuum Showing Types of Motivation With Their Regulatory Styles, Loci of Causality, and Corresponding Processes


Expectancy- Value Theory – Wigfield and Eccles

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This theory maintains that the beliefs of ability, value or importance of the behaviour and how well it will be achieved or expectancy are the key determinates of motivation. The value is determined by importance of doing well at the task, enjoyment of doing the task, usefulness of the task in the future, and the cost of the task being the effort and time required to execute the task. Expectancy is determined by ability and performance beliefs and these are influenced by ones perception of previous experiences using self-schema and affective memories to construct their behavioural prediction [30].Developmental influences on the expectancy–value theory are revealed at a young age and are active well into adulthood. At young schooling age children have clear beliefs about what they are good at and the value of the action, across varied and different tasks. The importances of maths or playing an instrument are clearly defined if you ask a child. Though mostly younger children believe themself to own higher achievement abilities than a more realistic level, and as we age our ability performance beliefs decrease. This is due to either becoming more aware of personal ability in comparison to peers or because the evaluation is more salient and competition arises [30]. These decreases continue in to high school with ability-related beliefs and the subjective values of a task varying through schooling years. As an adult expectancy-value theory maintains that the level of an ability and performance beliefs reach more realistic levels though the values of tasks are still variable between individuals.

Stages of moral development - Kohlberg

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The theory follows and expands on Piaget’s stages of development; it outlines stages of moral development, defining the differences between what the right behaviour is and what wrong behaviour is [31]. The concepts of punishment, obedience and reward are combined in the pre conventional level. This stage then builds up to stage two a conventional level that adapts to social rules, interpersonal expectations and the roles of relationships. With a third level post conventional level denotes abstract and personal ethical and social constructs of moral reasoning [32]. The development through life is then proposed to be influenced by the external social influences and the moral decision making of how to react to the stimuli. Kohlberg noted that not all people reach the highest level, yet the progression through the stages is age related [31]. This moral specific theory of development is a popular theory of contemporary psychologists, however it is specialised and hence needs to be complemented by other wider spaning theories of development to obtain the full concept of human development through the life cycle.

Sociocultural or social development theory - L.Vygotsky(1896-1934)

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This theory of development does not isolate the individual as the determinate of development. Instead the framework of development studies both the individual and the environment as one unit. Vygotsky (1978) beliefs that ‘every function in a child’s cultural development appears twice: first, on a social level, and later, on the individual level; first between people and then inside the child’ [33](pg57). Vygotsky elects that culture influences development by the habits, skills, abilities and tools one uses and is expected to use by their social group. Skills include hunting or farming, whilst abilities encompass tying knots or understanding the land. The tools include the systems of the sociocultural surrounding these include the language and writing systems. This theory suggests that the potential for development to occur happens in a Zone of proximal development. This zone requires social interaction to allow effective cognitive development; Whilst the level of individual cognitive development is limited by certain and specific age related differences. This theory complements Bandura’s work, a developmental approach determining that behaviour is learnt by observing others and the consequences of other peoples actions (vicarious reinforcement), using a number of cognitive processes that change with age; and maintains an active, nurture, stage like progression through life cycle development [16].

Affect theory - Tomkins (1911-1991) and Holinger, 2008

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This theory of development maintains there are 4 categories of affect, those being philosophical views, neurobiological processes, Darwin’s evolutionary concepts and Psychoanalytic factors. ‘Tomkins described affect as innate biological (universal) responses to various stimuli, with these responses being manifested in the skin, vocal apparatus, musculature and autonomic system, particularly in the facial region’ [34] pg 428. The theory outlines 10 affects in total these vary in presence due to level of stimulus increasing or decreasing and the density of neural firing performed in response. Different yet related stimuli excite the same primary effects. The affects of various stimuli are described as amplifiers of drives, which focus on both the environment and internal temperament of the individual. Due to the active development of an individual throughout life being influence by intrinsic factors and negative reactions to stimuli, Affect theory whilst comprehensive in characteristics that determine behaviour it is not followed by many in the developmental psychology field. This is due to many of Tomkins woks not being completed prior his death.

Conclusion

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References

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  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Bjorklund, D., & Blasi, C. H. (2012). Child and adolescent development. Belmont: Wadsworth.
  2. 2.0 2.1 2.2 2.3 2.4 Deci.E.L, & Ryan.R.M. (2000). The "what"and "why" of goal pursuits: Human needs and the self-determination of behaviour. Psychological Inquiry, 11, 227-268.
  3. Goebel, B.L., & Brown, D.R. (1981). Age differences in motivation related to Maslow's Need Hierarchy. Developmental Psychology, 17, 809-815.
  4. Li, S.-C. (2013). lifespan development of neuromodulation ofadaptive control and motivation as an otogenetic mechanism for developmental nieche construction. Developmental Science , 16 (2), 317-319.
  5. 5.0 5.1 5.2 Fifer, W. (2005). Normal and abnormal prenatal Development. The Cambridge encyclopedia of child development , 173-192. Cite error: Invalid <ref> tag; name "Fifer" defined multiple times with different content
  6. Fairchild, G. (2011). The developmental psychopathology of motivation in adolescence. Developmental Cognitive Neuroscience , 1, 414-429.
  7. 7.0 7.1 Bitan, T., Burman, D., Lu, D., Cone, N., Gitelman, D., Mesulam, M., et al. (2006). Weaker top-down modulation from the left inferior frontal gyrus in children. Neuro Image , 33, 991-998.
  8. 8.0 8.1 8.2 Fairchild, G. (2011). The developmental psychopathology of motivation in adolescence. Developmental Cognitive Neuroscience , 1, 414-429.
  9. Luna, B., Paulsen, D., Padmanabhan, A., & Geier, C. (2013). The Teenage Brain: Cognitive Control and Motivation. Current Directions in Psychological Science , 22 (2), 94-100.
  10. 10.0 10.1 10.2 Cite error: Invalid <ref> tag; no text was provided for refs named Luna
  11. 11.0 11.1 11.2 11.3 11.4 Gordon, I., Martin, C., Feldman, R., & Leckman, J. (2011). Oxytocin and social Motivation. Developmental Cognitive Neuroscience , 1, 471-493.
  12. Stienberg, L. (2004). Risk taking in adolescence:What changes and why? Annals of the New York Academy of Sciences , 51-58.
  13. Botting, N., Powls, A., Cooke, R., & Marlow, N. (1998). Cognitive and educational outcome of very low birthweight children in early adolescence. Developmental Medicine and Child Neurology , 652-660.
  14. Mortensen, E., Michaelsen, .., Sanders, S., & Reinisch, J. (2002). The association between duration of breastfeeding and adult intelligence. Journal of the American Medical Association , 287, 2365-2371.
  15. Fantz, R. (1963). Pattern vision in newborn infants. Science , 296-297.
  16. 16.0 16.1 16.2 Galotti, K. (2011). Cognitive development infancy through adolescence. London: Sage.
  17. Macfarlane, A. (1975). olfaction in the development of social preferences in the humane neonate. CIBA Foundation Symposism 33: Parent-infant interaction. Amsterdam: Elsevier.
  18. Schaal, B., Marlier, L., & Soussignan, R. (2000). Human foetuses learn odours from their pregnant mothers diet. Chemical senses , 729-737.
  19. 19.0 19.1 Decasper, A., & Spence, M. (1986). Prenatal maternal speech influences newborns' perception of speech sounds. Infant Behaviour and Development , 133-150.
  20. Feldman, R. (2007). Parent-infant synchromy. Current Directions in Psychological Science , 340-345.
  21. Rizzolatti, G., Fogassi, L., & Gallese, V. (2001). Neurophysiological mechanisms underlying the understanging snd imitation of action. Nature Reviews Neuroscience , 661-670.
  22. Sweeny, J., Mintun, M., Kwee, S., Wiseman, M., Brown, D., Rosenberg, D., et al. (1996). Positron emission tomography study of voluntary saccadic eye movements and spacial working memory. Journal of Neurophysiology , 454-468.
  23. Roth, T., Lubin, F., Funk, A., & Sweatt, J. (2009). Lasting epigenetic influence of early-life adversity on the BDNF gene. Biological Psychiatry , 760-769.
  24. 24.0 24.1 24.2 Goebel.B.L, & Brown.D.R. (1981). Age Differences in Motivation Related to Maslow's Need Hierarchy. Developmental Psychology , 17 (6), 809-815.
  25. Maslow.A.A. (1943). A Theory of Human Motivation. Psychological Review (50), 370-396.
  26. 26.0 26.1 Wyeth, P., Johnson, D., & Ziviani, J. (2013). Activity, Motion and Games forYoung Children. IE 2013 - Proceedings of the 9th Australasian Conference on Interactive Entertainment: Matters of Life and Death (p. 3). Melbourne, VIC, Australia: ACM International Conference Proceeding Series
  27. 27.0 27.1 27.2 Gillet, N., Vallerand, R., & Lafreniere, M.-A. (2012). Intrinsic and Extrinsic school motervation as a function of age: the mediating role of autonomy support. Social Psychology of Education , 15, 77-95.
  28. Lepper, M., Corpus, J., & Iyengar, S. (2005). Intrinsic and extrinsic motivation orientations in the classroom: Age differences and academic correlates. Journal of Educational Psychology , 97, 184-196.
  29. Gottfried, A., Marcoulides, G., Gottfried, A., & Oliver, P. (2009). A latent curve modle of parental motivational practices and developmental decline in math and science academic intrinsic motivation. Journal of Educational Psychology , 729-739.
  30. 30.0 30.1 Cite error: Invalid <ref> tag; no text was provided for refs named Wigfield
  31. 31.0 31.1 Kohlberg, L. (1981). Essays on Moral Development, Vol. I: The Philosophy of Moral Development. San Francisco, CA: Harper & Row.
  32. Kohlberg, L., & Hersh, R. (1977). Moral development. Theory in to Practice , 16 (2), 53-59.
  33. Vygotsky, L. S. (1978). Mind in society: The development of higher psychological processes. Cambridge, MA: Harvard University Press
  34. Holinger, P. (2008). Further Issues in the Psychology of Affect an Motivation: a Developmental perspective. Psychoanalytic psychology , 25 (3), 425-442.