This article describes human binocular vision. While it is focused primarily on human stereopsis, it also briefly tells about other binocular functions, including binocular summation, rivalry, and vergence, the eye movement that is driven by stereopsis. Stereopsis refers to the depth perception generated by small differences in the locations of visual features in the two retinal images; these differences in retinal location are called disparities. Disparities are detected by special binocularly driven cortical neurons whose properties are outlined here; the article also describes studies that have used fMRI imaging to show that many areas of human cortex respond to depth based on disparity. The development of stereopsis in human infants, as well as clinical abnormalities in stereopsis, is also documented.
Article
Binocular Vision
Suzanne McKee and Preeti Verghese
Article
Blood Pressure as a Biomarker in Gerontological Research
Thomas M. Hess, Erica L. O'Brien, and Claire M. Growney
Blood pressure is a frequently used measure in studies of adult development and aging, serving as a biomarker for health, physiological reactivity, and task engagement. Importantly, it has helped elucidate the influence of cardiovascular health on behavioral aspects of the aging process, with research demonstrating the negative effect of chronic high blood pressure on various aspects of cognitive functioning in later life. An important implication of such research is that much of what is considered part and parcel of getting older may actually be reflective of changes in health as opposed to normative aging processes. Research has also demonstrated that situational spikes in blood pressure to emotional stressors (i.e., reactivity) also have implications for health in later life. Although research is still somewhat limited, individual differences in personal traits and living circumstances have been found to moderate the strength of reactive responses, providing promise for the identification of factors that might ameliorate the effects of age-related changes in physiology that lead to normative increases in reactivity. Finally, blood pressure has also been successfully used to assess engagement levels. In this context, recent work on aging has focused on the utility of blood pressure as a reliable indicator of both (a) the costs associated with cognitive engagement and (b) the extent to which variation in these costs might predict both between-individual and age-related normative variation in participation in cognitively demanding—but potentially beneficial—activities. This chapter elaborates on these three approaches and summarizes major research findings along with methodological and interpretational issues.
Article
Boris Ananiev’s Theory of Self-Determination of Human Development
Irina A. Mironenko
Ananiev’s approach shares the Activity Theory (AT) paradigm, dominant in Soviet psychology. Ananiev builds on the main fundamentals of the AT paradigm, considering psyche as a special procreation of the matter, engendered by the active interaction of the individual with the environment. The unique feature of his approach to AT is that he turned it “toward the inside,” focusing on the relation of the human individual to his own physicality, to his own bodily substrate. Ananiev sought by his intention to keep a holistic vision of a human being, considering the latter in the context of his real life, that is, the bodily substrate in its biological specificity in context of the concrete sociohistorical life course of the personality. Like no other psychologist, Ananiev did not limit his research to the sphere of narrowly defined mental phenomena. He conducted a special kind of research, labeled as “complex,” in the course of which characteristics of the same subjects: sociological, socio-psychological, mental, physiological, and psychophysiological indicators—life events of the subjects—were monitored for many years. He focused on ontogenetic development in adulthood, which he, ahead of his time, considered as a period of dynamic changes and differentiated development of functions. The focus of his attention was on individual differences in the ontogenetic development of mental and psycho-physiological functions, especially those deviations from general regularities that resulted from the impact of the life course of the individual. Individualization, the increase of individual singularity, is the main effect of human development and its measure for Ananiev.
Ananiev developed a number of theoretical models and concepts. The best-known of Ananiev’s heritage is his theoretical model of human development, often named the “individuality concept.” According to this model, humans do not have any preassigned “structure of personality” or “initial harmony.” The starting point of human development is a combination of potentials—resources and reserves, biological and social. The human creates himself in the process of interaction with the world. Specialization, individually specific development of functions, appears here not as a distortion of the pre-set harmony of the whole but as the way of self-determining progressive human development. The most important practical task of psychology he viewed as psychological support and provision in the process of developing a harmonious individuality, based on the individual potentials.
Article
Dyslexia
Linda Siegel
Dyslexia, or a reading disability, occurs when an individual has great difficulty at the level of word reading and decoding. Comprehension of text, writing, and spelling are also affected. The diagnosis of dyslexia involves the use of reading tests, but the continuum of reading performance means that any cutoff point is arbitrary. The IQ score does not play a role in the diagnosis of dyslexia. Dyslexia is a language-based learning disability. The cognitive difficulties of dyslexics include problems with recognizing and manipulating the basic sounds in a language, language memory, and learning the sounds of letters. Dyslexia is a neurological condition with a genetic basis. There are abnormalities in the brains of dyslexic individuals. There are also differences in the electrophysiological and structural characteristics of the brains of dyslexics. Hope for dyslexia involves early detection and intervention and evidence-based instruction.
Article
Effects of Early Visual Deprivation
Brigitte Röder and Ramesh Kekunnaya
As a consequence of congenital blindness, compensatory performance in the intact sensory modalities has been documented in humans in many domains, including auditory and tactile perception, auditory localization, voice and language processing, and memory. Both changes of the neural circuits associated with the intact sensory systems (intramodal plasticity) and an activation of deprived visual cortex (crossmodal plasticity) have been observed in blind humans. Compensation in congenitally blind and late-blind individuals involves partially different neural mechanisms. If sight is restored in patients who were born with dense bilateral cataracts (opaque lenses preventing patterned light to reach the retina), considerable visual recovery has been observed in basic visual functions even after long periods of visual deprivation. Functional recovery has been found to be lower for higher-order visual processes, which has been linked to deficits in the functional specialization of neural circuits. First evidence has suggested that crossmodal plasticity largely retracts after sight restoration but that crossmodal activity does not seem to fully dissolve. In contrast, intramodal adaptations in the auditory system have been observed to persist after sight restoration. Except for predominantly subcortically mediated multisensory functions, many multisensory processes have been found to be altered even many years after sight restoration.
On the one hand, research in permanently blind humans has documented a high capability of the human neurocognitive system to adapt to an atypical environment. On the other hand, research in sight recovery individuals who had suffered a transient phase of visual deprivation following birth has demonstrated functional specific sensitive periods in the development of visual and multisensory neural circuits.
Article
Imprinting as Social Learning
Timothy D. Johnston
Imprinting is a form of rapid, supposedly irreversible learning that results from exposure to an object during a specific period (a critical or sensitive period) during early life and produces a preference for the imprinted object. The word “imprinting” is an English translation of the German Prägung (“stamping in”), coined by Konrad Lorenz in 1935 to refer to the process that he studied in geese. Two types of imprinting have traditionally been distinguished: filial imprinting, involving the formation of an immediate social attachment to the mother or a mother-substitute, and sexual imprinting, involving the formation of a sexual preference that is manifested later in life. Both types of imprinting were subject to extensive experimental study beginning around 1950. Originally described in precocial birds (ducks, geese, and domestic chickens), imprinting has also been used to explain the formation of early social attachments in other species, including human infants. Imprinting has served as a useful model for studying the neural processes involved in learning and behavioral development and has provided a framework for thinking about other developmental processes.
Article
Inflammation As a Biomarker Method in Lifespan Developmental Methodology
Stephanie J. Wilson, Alex Woody, and Janice K. Kiecolt-Glaser
Inflammatory markers provide invaluable tools for studying health and disease across the lifespan. Inflammation is central to the immune system’s response to infection and wounding; it also can increase in response to psychosocial stress. In addition, depression and physical symptoms such as pain and poor sleep can promote inflammation and, because these factors fuel each other, all contribute synergistically to rising inflammation. With increasing age, persistent exposure to pathogens and stress can induce a chronic proinflammatory state, a process known as inflamm-aging.
Inflammation’s relevance spans the life course, from childhood to adulthood to death. Infection-related inflammation and stress in childhood, and even maternal stress during pregnancy, may presage heightened inflammation and poor health in adulthood. In turn, chronically heightened inflammation in adulthood can foreshadow frailty, functional decline, and the onset of inflammatory diseases in older age.
The most commonly measured inflammatory markers include C-reactive protein (CRP) and proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α). These biomarkers are typically measured in serum or plasma through blood draw, which capture current circulating levels of inflammation. Dried blood spots offer a newer, sometimes less expensive collection method but can capture only a limited subset of markers. Due to its notable confounds, salivary sampling cannot be recommended.
Inflammatory markers can be added to a wide range of lifespan developmental designs. Incorporating even a single inflammatory assessment to an existing longitudinal study can allow researchers to examine how developmental profiles and inflammatory status are linked, but repeated assessments must be used to draw conclusions about the associations’ temporal order and developmental changes. Although the various inflammatory indices can fluctuate from day to day, ecological momentary assessment and longitudinal burst studies have not yet incorporated daily inflammation measurement; this represents a promising avenue for future research.
In conclusion, mounting evidence suggests that inflammation affects health and disease across the lifespan and can help to capture how stress “gets under the skin.” Incorporating inflammatory biomarkers into developmental studies stands to enhance our understanding of both inflammation and lifespan development.
Article
Integrated Theories of Biological Aging
Conscience P. Bwiza, Jyung Mean Son, and Changhan Lee
Aging is a progressive process with multiple biological processes collectively deteriorating with time, ultimately causing loss of physiological functions necessary for survival and reproduction. It is also thought to have a strong evolutionary basis, largely resulting from the lack of selection force. Here, we discuss the evolutionary aspects of aging and a selection of theories founded on a variety of biological functions that have been shown to be involved in aging in multiple model organisms, ranging from the simple yeast, worms, flies, killifish, and rodents, to non-human primates and humans. The conglomerate of distinct theories has together revolutionized aging research in the past several decades, far more than what humankind has known since the dawn of civilization. However, not one theory alone can independently explain aging and should not be interpreted out of context of the cell and organism in its entirety. That said, the 21st century has been and will be an exciting time in the field of aging, with scientific advances on health span and lifespan being made at multiple fronts of biology and medicine in an unprecedented scale.
Article
Methodology for Twin Studies of Aging
Michael J. Lyons, Chandra A. Reynolds, William S. Kremen, and Carol E. Franz
The rapidly increasing number of people age 65 and older around the world has important implications for public health and social policy, making it imperative to understand the factors that influence the aging process. Twin studies can provide information that addresses critical questions about aging. Twin studies capitalize on a naturally occurring experiment in which there are some pairs of individuals who are born together and share 100% of their segregating genes (monozygotic twins) and some pairs that share approximately 50% (dizygotic twins). Twins can shed light on the relative influence of genes and environmental factors on various characteristics at various times during the life course and whether the same or different genetic influences are operating at different times. Twin studies can investigate whether characteristics that co-occur reflect overlapping genetic or environmental determinants. Discordant twin pairs provide an opportunity for a unique and powerful case-control study. There are numerous methodological issues to consider in twin studies of aging, such as the representativeness of twins and the assumption that the environment does not promote greater similarity within monozygotic pairs than dizygotic pairs. Studies of aging using twins may include many different types of measures, such as cognitive, psychosocial, biomarkers, and neuroimaging. Sophisticated statistical techniques have been developed to analyze data from twin studies. Structural equation modeling has proven to be especially useful. Several issues, such as assessing change and dealing with missing data, are particularly salient in studies of aging and there are a number of approaches that have been implemented in twin studies. Twins lend themselves very well to investigating whether genes influence one’s sensitivity to environmental exposures (gene-environment interaction) and whether genes influence the likelihood that an individual will experience certain environmental exposures (gene-environment correlation). Prior to the advent of modern molecular genetics, twin studies were the most important source of information about genetic influences. Dramatic advances in molecular genetic technology hold the promise of providing great insight into genetic influences, but these approaches complement rather than supplant twin studies. Moreover, there is a growing trend toward integrating molecular genetic methods into twin studies.
Article
Music Perception
Marcus T. Pearce
Music perception covers all aspects of psychological and neural processing invoked while listening to music. In order to make sense of a musical stimulus, the perceptual system must infer an internal representation of the structure present in a piece of music, including the attributes of individual events (including pitch, timbre, loudness, and timing), groups of events (such as chords, voices, and phrases), and structural relationships between such groups, so that larger-scale aspects of musical form and thematic structure can be perceived. Such representations are stored in memory at timescales ranging from seconds for echoic memory to decades in the case of long-term memory for music, which consists of schematic knowledge of musical styles, veridical memory for particular familiar pieces of music, and episodic memory for music heard at a particular place and time. Stored representations of music allow the generation of top-down expectations for the attributes of forthcoming events while listening to music, which play a role in the perception of music as it unfolds dynamically in time and also the emotional and aesthetic experience of music. Music is a communicative medium conveying affective meaning from the composer and performer to the listener, via several psychological mechanisms and using a range of cues in the music, some of which are universal, others culture-specific. Individuals show behavioral and physiological effects of listening to music from birth onward and learn the syntactic structure of the musical styles to which they are exposed within their culture, shaping their music perception. Some individuals undertake explicit musical training, which can additionally shape their perception of music, sometimes in fundamental ways. Listening to music can impair performance on concurrent tasks involving working memory due to competing access for resources but can improve performance when listening takes place prior to the task due to its positive effect on affective state. Music is a universal human cultural phenomenon whose complexity requires the activation of a diverse range of perceptual and cognitive mechanisms, making it an interesting target for psychological and neuroscientific investigation.
Article
Psychological Stress and Cellular Aging
Idan Shalev and Waylon J. Hastings
Stress is a multistage process during which an organism perceives, interprets, and responds to threatening environmental stimuli. Physiological activity in the nervous, endocrine, and immune systems mediates the biological stress response. Although the stress response is adaptive in the short term, exposure to severe or chronic stressors dysregulates these biological systems, promoting maladaptive physiology and an accelerated aging phenotype, including aging on the cellular level. Two structures implicated in this process of stress and cellular aging are telomeres, whose length progressively decreases with age, and mitochondria, whose respiratory activity becomes increasingly inefficient with advanced age. Stress in its various forms is suggested to influence the maintenance and stability of these structures throughout life. Elucidating the interrelated connection between telomeres and mitochondria and how different types of stressors are influencing these structures to drive the aging process is of great interest. A better understanding of this subject can inform clinical treatments and intervention efforts to reduce (or even reverse) the damaging effects of stress on the aging process.
