al residenti al treatment (halfway hous- ing), and intensive or noninte nsive outpatient programs. Best Practices Guidelines Both Health Canada and the NIDA have indepen- dently developed a series of research-driven best practices guidelines for drug abuse treatment and rehabilitation. Some highlights of these best practices include the following: • Pharmacotherapies such as methadone and disulfi- ram can be effective as supplemental treatments when used in a controlled setting. • Behavioral therapies such as relapse prevention pro- grams, behavioral self-control therapy, and behav- ioral contracting have been shown to be useful when administered either individually or in group settings. • In terms of alcohol abuse, a community reinforce- ment approach has been shown to be effective for those with few social resources and relatively severe use. • Marital therapy and social skills training are both well supported by research. • Stress management interventions have been shown to be useful as part of alcohol treatment programs. • Services should be flexible and individualized, and guidelines for the selection of appropriate services are essential. No single treatment is appropriate for all individuals, and treatment needs will likely change as treatment progresses. • Group therapy is often preferable to individual treat- ment, unless otherwise contraindicated. • Although research generally supports the relative cost-effectiveness of outpatient treatment, some individuals may benefit from both residential and outpatient or day programs. • Effective treatment combines interventions that address the multiple needs of the individual, not just his or her drug use. • Brief interventions of up to eight sessions have been shown to be especially effective for socially stable individuals with low to moderate alcohol dependence, Drug Abuse 283 and are usually as effective as treatments of a longer duration for this group of individuals. • Counseling provided by competent therapists with strong interpersonal skills is related to positive outcomes. • The majority of those who have drug abuse pro- blems do not seek help; therefore, more effort is required to increase awareness of specialized ser- vices to the general public as well as to health ser- vice providers. It is expected that widespread application of these guidelines in drug abuse treatment will contribute to increased positive outcomes for substance-abusing individuals seeking support. Prevention Many people believe efforts at preventing drug abuse are vastly underfunded in comparison to the funds put toward treatment. Prevention in the context of drug abuse refers to the avoidance or mitigation of drug abuse and problems associ ated with drug use. Drug abuse prevention can involve primary, secondary, or tertiary prevention. The goal of primary prevention is to prevent drug use or abuse from occurring in the first place. Early education campaigns that encourage chil- dren to ‘‘just say no’’ would be an example of a primary prevention strategy. Secondary prevention involves interventions applied to those who are already in the early stages of using or abusing drugs in order to pre- vent the development of additional problems. An example of secondary prevention would be mandated alcohol education classes for those convicted of driving under the influence. Tertiary prevention involves reduc- ing or stopping further dete rioration among those with an established history of drug abuse. Harm reduction strategies designed to reduce harmful effects for those who continue to abuse drugs are seen as tertiary pre- vention strategies. An example of a harm reduction strategy is safe injection sites, such as those in Vancou- ver, British Columbia, Canada, that permit individuals to inject self-obtained illeg al drugs in a setting staffed by medical professionals in an effort to prevent over- doses and the spread of communicable diseases. Three major models of drug abuse prevention have emerged over the years, each with its own underlying philosophy and subsequent suggestions for prevention policies. The sociocultural model argues that social norms are the key factor in promoting the abuse of drugs. An example of the sociocultural model of pre- vention is social-norm education (as provided by many college health centers and college counseling centers), which seeks to counter common misperceptions about typical levels and patterns of drug usage. The con- sumption model argues that the prevalence of drug abuse is a direct function of the average levels of con- sumption in a given culture (e.g., the more the indivi- duals in a culture drink, the more individuals in that culture who will abuse alcohol) and seeks to minimize the negative consequences of drug use through the implementation of restrictions. Higher taxes and age minimums for legal alcohol consumption would fall within the consumption model of prevention. The pro- scriptive model goes one step further and argues that if the availability of drugs (pa rticularly alcohol) is com- pletely prohibited, those who continue to abuse drugs can be regarded as bad or immoral. Therefore, the pro- scriptive model of prevention advocates for prohibition of availability and complete abstinence. The American Alcohol Prohibition Era (1921 to 1932) is an example of the proscriptive model at work. In the past, several mass media campaigns have been aimed at youth and young adults in an effort to reduce drug abuse. Although these campaigns have been shown to increase public awareness and knowl- edge about drugs, their effectiveness at actually reduc- ing drug use and abuse has not been consistently demonstrated. A recent prevention strategy that has shown promise is resistance skills training, which helps youth develop their probl em-solving and decision- making skills. It also seeks to help youth develop cognitive skills for resisting media-based drug use mes- sages, increase self-awareness and self-esteem, learn nondrug coping strategies, and develop interpersonal communication and assertiveness skills. The most widely used program of thi s kind in the United States is the Drug Abuse Resistance Education (DARE) pro- gram. Unfortunately, research on its effectiveness has yielded mixed results. Robinder P. Bedi and Carlton T. Duff See also Diagnostic and Statistical Manual of Mental Disorders Further Readings American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed., Text rev.). Washington, DC: Author. 284 Drug Abuse Johnston, L. D., O’Malley, P. M., Bachman, J. G., & Schulenberg, J. E. (2006). Monitoring the future national results on adolescent drug use: Overview of key findings , 2005 (NIH Pub. No. 06–5882). Bethesda, MD: National Institute on Drug Abuse. Johnston, L. D., O’Malley, P. M., Bachman, J. G. & Schulenberg, J. E. (2006, December 21). Teen drug use continues down in 2006, particularly among older teens; but use of prescription-type drugs remains high. Retrieved January 14, 2007, from http://www.monitoringthefuture.org Lukas, S. (1993). Where to start and what to ask: An assessment handbook. New York: Norton. McLaughlin, T. F., & Vacha, E. F. (1993). Substance abuse prevention in the schools: Roles for the school counselor. Elementary School Guidance & Counseling, 28, 124–132. Migneault, J. P., Adams, T. B., & Read, J. P. (2005). Application of the transtheoretical model to substance abuse: Historical development and future directions. Drug and Alcohol Review , 24 , 437–448. Rubin, E. (2003). Integration of theory, research, and practice: A clinician’s perspective. In F. Rotgers, J. Morgenstern, & S. T. Walters (Eds.), Treating substance abuse: Theory and technique (2nd ed., pp. 343–363). New York: Guilford. Schydlower, M., Anglin, T. M., Fuller, P. G., Jr., Heyman, R. B., Jacobs, E. A., et al. (1995). The role of schools in combatting substance abuse. Pediatrics , 95 , 784–785. Terry-McElrath, Y. M., Johnston, L. D., O’Malley, P. M., & Yamaguchi, R. (2005). Substance abuse counseling services in secondary schools: A national study of schools and students, 1999–2003. Journal of School Health , 75 , 334–341. Thather, D. L., & Clark, D. B. (2006). Adolescent alcohol abuse and dependence: Development, diagnosis, treatment and outcomes. Current Psychiatry Reviews , 2 , 159–177. Tolan, P., Szapocznik, J., & Sambrano, S. (Eds.). (2007). Preventing youth substance abuse: Science-based programs for children and adolescents. Washington, DC: American Psychological Association. Vega, R. R., & Seligman, L. (2005). Diverse drug abusing populations. In R. H. Coombs (Ed.), Addiction counseling review (pp. 129–148). Mahwah, NJ: Lawrence Erlbaum. Web Sites Center for Substance Abuse Prevention: http://prevention.samhsa.gov/ Higher Education Center for Alcohol and Other Drug Abuse and Violence Prevention: http://www.higheredcenter.org Office of Safe and Drug-Free Schools: http://www.ed.gov/about/offices/list/osdfs/ D YNAMICAL S YSTEMS Educational psychology focuses on theories of learn- ing that ultimately affect how students are taught. Behavioral learning theories influenced the teaching/ learning process for more than 50 years. In the 1960s, the information-processing approach brought the mind back into the learning process. The current emphasis on constructivism integrates the views of Jean Piaget, Lev Vygotsky, and cognitive p sychology. Additionally, recent scientific advances have allowed researchers to shift attention to biological processes in cognition. The problem is that these theories do not provide an inte- grated approach to understandi ng principles responsible for differences among students in cognitive develop- ment and learning ability. Dynamic systems theory offers a unifying theoretical framework to explain the wider context in which learning takes place and the processes involved in individual learning. Dynamic (or dynamical) systems theory is part of a paradigm shift involving the acceptance of chaos and complexity as theoretical frameworks in physics, biology, chemistry, engineering, ecology, and psy- chology. Its concepts can be applied to any systems that change over time. It emphasizes the complexity of learning and the students themselves. It recognizes the importance of context in change. It connects the physical with the mental. It allows teaching and learn- ing to be connected processes. Dynamical Systems Are Self-Organizing Dynamic implies synergistic, changing, and chaotic (i.e., underlying order that appears random). System denotes an assemblage of interacting components whose essential properties arise from the relationships between its parts. Students, teachers, classrooms, schools, and school districts make up dynamical sys- tems in education. Students and teachers are individuals made up of diverse systems—biological, affective, and cognitive. There is also diversity base d on race, ethnicity, gender, disability, and socioecono mic status—other systems that are an integral part of students and teachers. All of these systems contribute to individual differences in rate of learning, level of thinking, memory, and moti- vation. Pedagogically, teachers need to be aware of the dynamic complexity of their students and themselves Dynamical Systems 285 in order to more effectively understand what occurs in the teaching-learning proce ss. For example, an African American student who has lived in a rural town will perceive information differently from an African American student who has been raised in an inner-city ghetto. Even though both students are African Ameri- can, the differences in the systems that make up who they are will contribute to diverse outcomes. If both are learning the word field, their understanding of the meaning of this word will reflect their different experi- ences. The same teaching strategy may not work for both of them. For one, a trip to a field might be neces- sary whereas the other will have experience with fields and can easily make a connection. A view of students as dynamic systems emphasizes the individuality and complexity of all students. Each dynamic system, in addition to being fluid and integrative, exists in a state space , which is an abstract construct depicting the range of behavior open to a sys- tem and constrained by the degrees of freedom avail- able to the elemental components of the system. Each student has his or her own state space or possible beha- viors. For example, a student whose family speaks Spanish at home is going to be constrained by English being a second language. His or her state space will be different from that of a student for whom English is a primary language. In order to be effective, a teacher needs to be sensitive to the different state spaces of his or her students. Some students may be incapable of car- rying out certain behaviors because of the limits of their state space. The student with Spanish as the primary language may be incapable of understanding certain English idioms until he or she has learned other words first and changed his or her state space through self- organization. Where a system is located in state space is often determined through self-organization, which occurs whenasystemisattractedtoapreferredstateof being out of many potential states. The individual components of a system emerge into new patterns (states of being) without anyone or anything directing this change. Self-organization emerges from the con- fluence of components within the system. In order for self-organization to occur, the system must be com- plex and open to changes in the environment. Self-organizing, nonlinear dynamic systems tend to migrate toward certain conditions or behaviors that are called attractors. Attractors have varying degrees of stability. Some are easily changed, such as the heart rate when exercising. Others are not easily changed, such as the stomach producing acid in response to food. An attractor state for a student might be his or her read- ing level, which may be stable for a long period of time. Systems will remain in a certain state space until a perturbation pushes the system or increases the sys- tem’s attraction to another state. Perturbation is a dis- turbance to the system. When disturbed, a system may move away from its present attractor and toward a new attractor, resulting in a phase shift. A phase shift is a new form that emerges from the loss of sta- bility of the existing forms. For example, the student whose reading level has been stable for a time period might change to a higher level because of an interest in a more difficult book. The resulting phase shift might be observed as the student begins reading chap- ter books instead of picture books. There has been a phase shift in reading levels. From a dynamic systems approach, learning is a self-organizational process on the part of the indi- vidual. The student undergoes phase shifts (transi- tions) in which the cognitive system self-organizes and new patterns of understanding emerge. Students pass from one organized state of the system to another. Along with the cognitive system undergoing change, neuronal networks are strengthened. As these systems change, they affect the other systems that make up the individual student. Phase shifts can also be facilitated by a control parameter. A control parameter is a variable outside the system to which the system is sensitive and that moves the system through different states. Teachers use control parameters to perturb the attractor states of the students. In pedagogy, a control parameter is the teaching method. Some teaching methods are more successful than others. If successful, self-organi- zation (learning) occurs. If there is no immediate self- organization, then the control parameter perturbation may disturb the system so that at some later point in time, self-organization may occur. For example, if a teacher is focusing on addition in an elementary classroom, he or she will use methods to bring about an understanding of addition. When a student understands what addition is, he or she undergoes a transition. Not only has his or her cogni- tive system changed, but biologically, there are changes in the brain; emotionally, the student might feel satisfaction and pride about mastering something in school; and environmentally, the student might be able to use addition in new aspects of his or her life, such as shopping with parents. The student, as 286 Dynamical Systems a dynamic system, has self-organized and is no longer the individual he or she was prior to the new learning. One truth about learning is that it evolves over time. Therefore, learning does not occur in every student each time a topic is covered in class. What often occurs is a perturbation of the attractor state. There can be many small perturbations without a change in the cognitive system. It is when the system (student) self-organizes that learning takes place. For example, a teacher may introduce addition to students in a number of different ways—direct instruc tion, small group activities, indi- vidual worksheets. The actual comprehension of what addition means will occur in individual ways. Some students may understand addition from the first activ- ity, and therefore will self-organize, move to a new attractor state in which being able to add is the norm, and be able to demonstrate an understanding of addi- tion. Other students may require all three strategies before meaning is created. Each activity perturbs the attractor state of these students, but no self-organization occurs until all activiti es have been experienced. Dynamical Systems Are Nonlinear Besides self-organizing, dynamic systems are also non- linear , that is, output is not proportional to input. Tea- chers learn early that sometimes the best lesson plans do not bring about the learning that was sought. Pedagogi- cally, there is not always a direct relationship between teaching and learning. Som etimes, a teacher does not have direct control over the specific learning that goes on, such as in a cooperative learning group, where stu- dents can learn from other students without the teacher’s involvement. Most of the ti me, the teacher has to use a number of strategies to perturb the systems (students) until finally self-organization (learning) occurs. All Systems Have a History Dynamic systems theory espouses that all systems have a history that affects their states in the present. As the student acts, that action becomes part of his or her dynamical history. This history will then influence future actions. Fritjof Capra states that living structure is always a record of previous development. The his- tory of a system includes its tendencies and con- straints. Self-organization taking place in the present is constrained by self-organization of the past. The system’s history will affect its present state space, attractors, phase shifts, and control parameters. So, besides viewing students as dynamical sys- tems, teachers must be aware that each of these sys- tems (students) has a history that will affect his or her ability to learn. Some students have a history of doing well in school, understanding academic sub- jects, and having friends and supportive parents. Unless severely perturbed, these students will con- tinue to do well in school throughout their school lives and respond well to teaching strategies. Other students do not have such a positive experience in their pasts. They may have problems being in school, may have difficulties learning academic subjects, and do not have supportive parents. These students may be harder to reach and require larger perturbations to their systems before learning can occur. Their histories may interfere with success in school. These are often the students who present the challenge to teachers. Besides the students and te acher being systems with a history, the classroom community, too, is a system that has an ongoing, ever-changing history—a history of interactions within the enclosed walls of the class- room itself. No two days are alike in the classroom; indeed, no two moments in time are alike. The setup of the classroom—temperatur e, luminosity, desk orien- tation, ambient noise, odor s—defines its state space. Within that broader framework, each member of the classroom community, each student and teacher, is an independent, complex, nonlinear system with a unique state space of his or her own and his or her own unique and constantly changing history. The variability and unpredictability of the classroom environmental system keep it in constant flux. The environment also constrains the degrees of freedom available to individual students and teachers. For example, students learn to raise their hands to speak, speak softly or not at all while working, and get into line in the proper order. All of these constrain the behaviors of the students from what they might be if students did not have certain norms. Some students learn from this history of classroom behavior and automatically apply it in subsequent grades so that by the time the students reach later elementary years, the attractor state for classroom behavior is stabilized. Understanding Dynamical Systems Within the Context of the Whole Because a number of systems make up an individual, all of them, together, provide the essence of the Dynamical Systems 287 individual. Unlike the behaviorist reductionist view, which requires studying parts of the whole and then generalizing across the whole, dynamic systems the- ory purports that the whole is always different from the mere sum of its parts. Therefore, the parts must be studied and understood within the context of the larger whole. This holistic thinking moves the focus of research from objects to relationships. Studying learning in a classroom setting did not begin until the 1960s, yet this is where the majority of children’s aca- demic studies take place. Students are taught within groups of students, yet learning is a very individual activity. It is important for the teacher to know the history of each student in order to understand what attractors are present and what control parameters might facili- tate change. However, this is difficult to do because teachers are involved with groups of students in such a way that time and energy prohibit study of the vari- ous systems that make the student who he or she is. So instead, teachers use a variety of learning techni- ques in order to bring about learning in the most stu- dents possible. Besides the students being made up of different systems, the teacher also is a network of systems with his or her attractor states and state space. This will affect what types of pedagogical practices he or she will use in a classroom setting. For some teachers, teacher-centered strategies are what they are comfort- able using, and despite information to the contrary, they will continue in that attractor state because of its stability. Jane L. Abraham See also Continuity and Discontinuity in Learning; Piaget’s Theory of Cognitive Development Further Readings Capra, F. (1996). The web of life: A new scientific understanding of living systems. New York: Anchor. Edelman, G. M. (1992). Bright air, brilliant fire: On the matter of the mind. New York: Basic Books. Gagne, E. D. (1985). The cognitive psychology of school learning. Boston: Little, Brown. Gleick, J. (1987). Chaos. New York: Penguin. Kelso, J. A. S. (1995). Dynamic patterns: The self- organization of brain and behavior. Cambridge: MIT Press. Moore, D. S. (2001). The dependent gene: The fallacy of ‘‘nature vs. nurture.’’ New York: Henry Holt. Robertson, R., & Combs, A. (Eds.). (1995). Chaos theory in psychology and the life sciences. Mahwah, NJ: Lawrence Erlbaum. Thelen, E., & Smith, L. B. (1994). A dynamic systems approach to the development of cognition and action. Cambridge: MIT Press. Thelen, E., & Smith, L. B. (1998). Dynamic systems theories. In R. M. Lerner (Ed.), Handbook of child psychology: Vol. 1. Theoretical models of human development (5th ed., pp. 563–634). New York: Wiley. von Glaserfeld, E. (1984). An introduction to radical constructivism. In P. Watzlawick (Ed.), The invented reality (pp. 17–40). New York: Norton. D YSLEXIA Dyslexia is one of several types of learning disabilities that occurs in children who, despite strengths in other academic and cognitive abilities, experience extreme difficulty in learning to decode and spell printed words. This problem at the level of the single word impedes their ability to fluently read and comprehend connected text. Importantly, their reading difficulties do not stem from lack of educational opportunity, sensory acuity deficits, or socioeconomic disadvan- tage, although educational opportunity and socioeco- nomic status may interact with dyslexia to either reduce or exacerbate its severity. The International Dyslexia Association defines dyslexia as follows: A specific learning disability that is neurological in origin. It is characterized by difficulties with accu- rate and/or fluent word recognition and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provi- sion of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede the growth of vocabulary and back- ground knowledge. Estimates suggest that dyslexia occurs in 6 % to 17 % of the school-age population depending on how it is defined. Regardless of prevalence estimates, chil- dren with dyslexia comprise the bulk of children receiving special education services in the United States for students with learning disabilities. Although 288 Dyslexia dyslexia manifests in childhood with the onset of for- mal reading instruction, it has definable precursors that permit early detection before formal schooling. In the absence of targeted intervention, the deficiencies observed in childhood continue to be evident in the same individuals well into adulthood. Dyslexia may also occur concomitantly wit h other conditions, includ- ing other learning disabilities involving mathematics (dyscalculia) and written expression (dysgraphia), oral language disorders, and attention deficit disorder with or without hyperactivity. These co-occurrences are usu- ally comorbid, meaning that the child has more than one problem. Scientific understanding of dyslexia has dramati- cally increased in the past four decades. It is now widely accepted that dyslexia occurs on a continuum in much the same way as obesity or high blood pres- sure. What this means in practice is that dyslexia is not an all-or-nothing categorical disability. Instead, it occurs in degrees of severity. Establishing the cut point on the continuum at which word reading diffi- culties constitute a disability is not well established and accounts for the variability in prevalence esti- mates. Current classification schemes vary by state and by program type. In the United States, children can receive services for dyslexia as part of special education under the Learning Disabilities (LD) cate- gory in the Individuals with Disabilities in Education Act (IDEA), where problems with basic reading skills are one of the eight domains in which LD can occur. A few states, such as Texas and Louisiana, also pro- vide dyslexia services outside of special education. In most states, qualification for dyslexia services under the LD category would be based on an achievement/ IQ test discrepancy, with a number of discrepancy models in use from state to state. In the recent reauthorization of IDEA, states were also allowed to use response-to-intervention (RTI) as a mechanism for identifying learning disabilities including dyslexia as well as models based on discrepancies in achieve- ment relative to age. Regulations permitting the use of RTI for identification are just emerging from different states. Historical Roots and Theories Over the years, a number of other theories and result- ing treatments have gained and lost prominence in the field of dyslexia. A few of the most prominent theo- ries are briefly reviewed below. Deficits in Visual Perception Dyslexia was first described more than 100 years ago. By 1900, the condition was referred to as congeni- tal word blindness and was believed to be caused by difficulty in storing visual impressions of words. Build- ing on the assumption that the underlying causes of observed reading difficulties were based in deficits in visual processing, Samuel O rton outlined the first fully developed theory of dyslexia, which he called strepho- symbolia (twisted symbols). His theory suggested that children were experiencing d ifficulty in establishing hemispheric dominance within the brain, resulting in an inability to suppress mirror image counterparts, which was presumed to cause optic reversibility in visual perception that resulted in seeing symbols as reversed images (e.g., b as d;or was as saw). Although the basic tenets of Orton’s theory have not proved to be correct, they have been hugely influ- ential in driving the focus of subsequent theories and treatments of dyslexia even to the present time. It is from Orton’s theory of dyslexia that the widely held belief that the treatment of dy slexia requires multisen- sory methods of instruction stems. The underlying assumption being that by activating the auditory, tac- tile, and kinesthetic modal ities of learni ng, students are able to compensate for inherent weakness in the visual domain. In fact, the Orton–Gillingham method for teaching reading, or one of many derivatives of this method, is pervasive in the treatment of dyslexia even today. However, empirical support for these methods is mixed. Likewise, there is no indication that the multi- sensory aspects of this inst ruction are actually the salient aspects of the instruction. The content of these programs focuses on teaching alphabetic decoding, and this focus likely accounts for any effects achieved. Interventions that do not actu ally include multisensory aspects but do carefully teach alphabetic decoding have also achieved very positive r esults with this population. The view that dyslexia was caused by dysfunction in the visual perception system dominated the field until it was systematically evaluated in the 1970s and 1980s. Outcomes from these studies clearly demonstrated that the visual perception ability of dyslexic and normal readers was not different, a nd that visual perception ability does not predict performance of reading ability. Low-Level Visual Deficits Dyslexia has also been attributed to visual tracking problems assumed to be caused by ocular motor Dyslexia 289 deficiencies; visual masking effects associated with deficits in the transient visual system; and scotopic sensitivity syndrome (SSS) involving excess sensitiv- ity of the retina to particular frequencies of light, causing the brain to distort information. Of these theo- ries, SSS currently has the most prominence in prac- tice. The interventions recommended for SSS involve placing colored overlays over text or using tinted lenses designed to selectively filter out problem fre- quencies and make the text visually stable. The visual tracking theory of dyslexia has long been discredited by well-controlled eye movement studies finding no differences between poor and normal read- ers. Similarly, the evidence to support the theory of visual masking effects has been weakened by the find- ing that significant numbers of normal readers have similar transient system deficits. Likewise, independent reviews of the results of interventions based on SSS theory have not found specific associations of reading, dyslexia, and other disabilities. Perceptual-Motor and Cerebellar Deficits In the 1960s and 1970s, theories commonly attrib- uted the cause of dyslexia to perceptual-motor defi- cits. Although the specifics of each theory differed, they shared the common belief that a child must have adequate visual-motor functioning as a prerequisite for academic learning, and that motorical treatment was needed to reorganize neurological functioning to allow adequate visual-perceptional ability. The treat- ments aligned with these the ories included such things as having children practice creeping and crawling, walking on balance beams, standing on balance boards, and completing eye-tracking exercises. Although these theories and their accompanying treatments were very popular, they did little to improve the academic out- comes for children and have largely become extinct in practice. Despite these results, there has recently been some resurgence of this approach to treating dyslexia and other learning disabilities, despite the lack of scientific evidence for effectiveness. This is most apparent in the cerebellar theory of dyslexia proposed by Roder- ick Nicolson, Angela Fawcett, and Paul Dean. The hypothesis is that children with dyslexia fail to autom- atize reading and other cognitive and motor skills mediated by the cerebellum. There is little evidence that supports this hypothesis or the recommended interventions. Low-Level Auditory Deficits Another theory that has attracted attention more recently is put forth by Paula Tallal, who theorized that children with dyslexia are fundamentally impaired in processing acoustic stimuli characterized by spectral parameters that change rapidly in intensity. Although originally based on childre nwithorallanguagedisor- ders, Tallal expanded this hy pothesis to children with dyslexia, suggesting that dyslexia is caused by lower- level auditory problems interfering with the processing of sounds with rapidly changing properties, which in turn impairs speech percepti on and thus the acquisition of phonological awareness and phonological decoding. Early empirical evidence provided support for this the- ory, but more recent investigations have not found spe- cific associations of these perceptual problems with dyslexia. The treatments that have emerged from this theory, which involve using synthetic speech to slow down the acoustic stimuli, have not been found to have a major impact on reading skills in randomized, con- trolled experiments. Phonological Coding Deficits Currently, the theory that dyslexia is the result of weak phonological coding has accumulated substan- tial and converging scientific evidence to support it. Phonological coding is the ability to use speech codes to represent words and parts of words. Weakness in this domain results in poor phonemic awareness and letter-to-sound mapping, resulting in poorly specified phonological representation of words. These coding deficits result in difficulty in storing and retrieving words as unitized orthographic representations, and difficulty in processing alphabetic information in working memory. The theory suggests that difficulties in storage and retrieval impair the child’s ability to form necessary connective bonds between spoken and written words, which in turn impedes the storage of fully specified representations of word spellings and thus impedes fluency of word recognition. Evidence to support this theory comes from two sources. First, a relation between phonological coding and dyslexia can be inferred because children with dyslexia have consistently been found to perform sig- nificantly below normal readers on different assess- ments of phonological processing, Likewise, a causal link can be inferred because intervention studies directly addressing phonological coding deficits have 290 Dyslexia repeatedly demonstrated positive outcomes on the reading outcomes of children with dyslexia. There is controversy over the exact manifestations and contri- butions of different phonological processing domains, but the link of word reading and phonological proces- sing, and the extrapolation to dyslexia, is widely rec- ognized as a major scientific discovery. Neurobiological Correlates Dyslexia has always been assumed to be neurobiolo- gically based. However, only recently have the neuro- logical and biological causes of dyslexia been able to be examined directly rather than just inferred. Genetics Studies of the heritability of dyslexia show that there is a strong genetic link for reading and reading disability. For example, a child whose parents had reading problems is eight times more likely to experi- ence a reading problem; 25 % to 60% of parents of children who are dyslexic also experienced significant reading difficulties; and the rate of concurrent dys- lexia among identical twins is above 80 % , but below 50 % for fraternal twins. The estimates of the genetic contribution ranges from 50 % to 80 % depending on age, schooling, and other sample characteristics. Fur- thermore, recent studies have identified a constellation of specific genes involved in dyslexia. Multiple researchers have identified an area on chromosome 6, and chromosome 15 has been identified by several researchers. Potential markers on chromosome 1 and 2 have also been reported but not replicated. Even though there is a clear genetic link to dys- lexia, these studies do not indicate that the genetic links are specific to dyslexia, but instead are linked to reading and the variability in reading skills that char- acterizes any population. In addition, the same body of research demonstrates that the environment plays an important role in determining reading outcomes for individual children. Whether or not significant reading problems will develop in a child with a genetic predisposition for dyslexia also depends on what types of reading experiences that child is provided in his or her home and school environment. Even if heritability is strong, the genetic contribution does not mean that the reading problem is immutable to intervention, although more intense and targeted instruction may be needed. Brain Function The evidence that dyslexia is greatly influenced by environmental factors is supported in recent neuroi- maging studies of brain function in students with and without dyslexia. In these studies, various neuroima- ging techniques, such as positron emission tomogra- phy, functional magnetic resonance imaging, and magnetic source imaging, are used to assess the brain’s response to cognitive challenges. The findings from studies using these techniques converge to show that tasks requiring reading are associated with increased activation with the basal surface of the tem- poral lobe, the posterior position of the superior, the middle temporal gyri, and the inferior frontal lobe. Magnetic source imaging studies, which allow time sequences within the brain to also be mapped, demon- strate that in normal readers, the occipital areas of the brain that support primary visual processing are acti- vated first, followed by regions in the basal temporal areas in both right and left hemispheres. This is fol- lowed by simultaneous activation in three areas of the temporal and parietal areas corresponding to the supe- rior temporal gyrus, Wernicke’s area, and the angular gyrus, often more predominantly in the left hemi- sphere. Students with dyslexia activate the same regions of the brain, but there is often much less left hemisphere activation and differences in the temporal sequences of brain activation. More recently, a series of studies has been con- ducted to determine the impact of carefully designed instruction on phonological coding on the brain acti- vation patterns of children with or at risk for dyslexia. In each of these studies, the brain activation patterns of children at risk for dyslexia (i.e., 5- and 6-year- olds) or identified as dyslexic (i.e., 7- to 17-year-olds) show predominantly normalizing patterns after well- designed, intense interventions. Importantly, this find- ing has been found among both young readers prior to the onset of reading difficulties (i.e., intervention in first grade) and older children and adults who have experienced serious reading difficulties. These studies indicate that the neural systems that mediate word recognition and dyslexia are malleable and responsive to intervention. Effective Treatment Since the early 1990s, a number of studies have care- fully evaluated interventions designed to prevent or Dyslexia 291 remediate dyslexia. From this body of research, we now know much about what constitutes effective intervention for these children. Perhaps the most important finding is that the needs of children with dyslexia are not unique to only children with dyslexia. The same type of instruction that is effective with these children is also highly effective for other chil- dren who experience reading difficulties for other rea- sons, such as economic disadvantage. Likewise, the critical components of this instruction are the same for even normally developing children, although the level of intensity and amount of repetition needed will be greater for children with dyslexia. This critical content includes explicit and strategic instruction to ensure that children develop high levels of phonemic awareness; in-depth knowledge of letter- sound correspondence, including the many spelling variations; acquisition of accurate, quick, and flexible word recognition skills moving beyond the single syl- lable; smooth, fluent oral reading through adequate practice reading increasingly more complex text; and strategies for the deep processing of text. For the treatment of dyslexia, the most crucial component of instruction is the inclusion of explicit instruction in fluent word recognition that includes phonological recoding (i.e., sounding out words) as a word recogni- tion strategy. Phonological recoding appears to account for individual differences in word recognition in both children and adults and is at the heart of phonological coding problems. When instruction is sufficiently intensive and integrates these various components into daily instruction that cumulatively becomes increasingly more complex, children with dyslexia improve considerably in not only accuracy of their word recognition skills, but in their overall reading ability. Particularly striking results are apparent among young children who have not yet experienced reading difficulties, but who have risk characteristics of dys- lexia. In multiple studies, the occurrence of reading problems among students at risk for dyslexia and other reading problems has been reduced to below 1.5 % of the total population. One of the most exciting developments in read- ing research is dramatic growth in researchers’ under- standing of which skills predict a phonological processing core deficit. Today, researchers can confi- dently predict which children are most at risk for developing dyslexia and other reading problems as young as kindergarten age. Thus, it is now possible to identify risk for dyslexia early, provide high-quality intervention before failure has occurred, and in most cases normalize reading ability. Early literacy skills that have been demonstrated to accurately predict risk in young children include (a) phonemic awareness; (b) knowledge of letter names and sounds; and © speed of lexical retrieval measured through the rapid naming of objects, colors, digits, or letters. For children who are not identified early, the out- look is not as positive, with reading problems becom- ing more difficult to remediate by the end of third grade. Older children require more intense interven- tions, occurring for longer periods of time, than do younger children. Although the impact of early pre- ventive and later remedial approaches are comparable, older children are usually so far behind that it is diffi- cult to provide the intensity and reading experience that will make them completely proficient readers. Although the outcomes for these groups of children can be very impressive, major concerns remain about the development of fluent reading ability among older students even after intervention, partly because of lack of reading experience. Likewise, these children often have persistent deficits in vocabulary and comprehen- sion that also may reflect an earlier inability to access print, as well as co-occurring problems with oral language development that affect listening and read- ing comprehension independently of phonological processing. Instructional Programming Programming to prevent or treat dyslexia and other reading difficulties has proven a great challenge within the public schools. Current proposals recom- mend a multitiered model of reading intervention. In most of the proposed multitiered models, Tier 1 is improved classroom-level general education core reading instruction so that critical content is taught well from the beginning. Children who experience difficulty in spite of receiving quality classroom-level instruction move into more intense, small group inter- vention (Tier 2) provided in addition to their core (Tier 1) instruction. The fo cus is not on labeling chil- dren, but rather on providing services to children at risk for reading failure f or any reason. Only after a child fails to respond adequately to the first two levels of instruction would a child be considered dyslexic, requiring Tier 3, or ongoing, support. Tier 3 interven- tion is typically described as having greater intensity and duration than Tier 2 intervention. Different models 292 Dyslexia vary in the point at which special education eligibility and services would be provided. Understanding Dyslexia In the past few decades, much progress has been made in understanding both the causes and treatment of dyslexia. It is now understood that dyslexia is a neurobiologically based disorder of phonological core processing ability that causes individuals to experience severe difficulty in reading and spelling at the level of the single word. Furthermore, it is now known that although genetics plays a large role in determining if a child has a predisposition for devel- oping dyslexia, the environment also plays a large role in determining the level of dyslexia expressed in any one individual. Environments that provide repeated and careful opportunities to practice phono- logical coding will result in a decreased expression of dyslexia. Furthermore, dyslexia is treatable, even among older children, although outcomes are gener- ally better for younger children. However, this is sim- ply because younger children have not yet fallen behind and thus don’t have as much ground to cover in order to catch up. Patricia G. Mathes and Jack M. Fletcher See also Learning; Learning Style; Reading Comprehension Strategies; Special Education Further Readings Aylward, E. H., Richards, T. L., Berninger, V. W., Nagy, W. E.,Field,K.M.,Grimme,A.C.,etal.(2003).Instructional treatment associated with changes in brain activation in children with dyslexia. Neurology, 22 , 212–219. Eden, G. F., Jones, K. M., Cappell, K., Gareau, L., Wood, F. B., Zeffireo, T. A., et al. (2004). Neural changes following remediation in adult developmental dyslexia. Neuron , 44 , 411–422. Fletcher, J. M., Lyon, G. R., Fuchs, L. S., & Barnes, M. A. (2007). Learning disabilities: From identification to intervention. New York: Guilford. Mathes, P. G., Denton, C. A., Fletcher, J. M., Anthony, J. L., Francis, D. J., & Schatschneider, C. (2005). The effects of theoretically different instruction and student characteristics on the skills of struggling readers. Reading Research Quarterly , 40 (2), 148–182. Orton, S. (1928). Specific reading disability- strephosymbolia. Journal of the American Medical Association , 90 , 1095–1099. Pakorni, J. L., Worthington, C. K., & Jamison, P. J. (2004). Phonological awareness intervention: Comparison of Fast For Word, Earobics, and LiPS. Journal of Educational Research , 97 (3), 147–157. Schatschneider, C., Francis, D. J., Carlson, C. D., Fletcher, J. M., & Foorman, B. R. (2004). Kindergarten prediction of reading skills: A longitudinal comparative analysis. Journal of Educational Psychology , 96 (2), 265–282. Shaywitz, B. A., Shaywitz, S. E., Blachman, B. A., Pugh, K. R., Fulbright, R. K., Skudlarski, P., et al. (2004). Development of left occipito-temporal systems for skilled reading in children after a phonologically-based intervention. Biological Psychiatry , 55 , 926–933. Simos, P. G., Fletcher, J. M., Sarkari, S., Billingsley- Marshall, R. L., Denton, C. A., & Papanicolaou, A. C. (2007). Intensive instruction affects brain magnetic activity associated with oral word reading in children with persistent reading disabilities. Journal of Learning Disabilities , 40 (1), 37–48. Stanly, G., Smith, G. A., & Howell, E. A. (1983). Eye movements and sequential tracking in dyslexic and control children. British Journal of Psychology , 74 , 181–187. Torgesen, J. K., Wagner, R. K., Rashotte, C. K., Rose, E., Lindamood, P., Conway, T., & Garvan, C. (1999). Preventing reading failure in young children with phonological processing disabilities: Group and individual response to instruction. Journal of Educational Psychology , 91 , 579–593. Vaughn, S. R., Wanzek, J., Woodruff, A. L., & Linan-Thompson, S. (in press). A three-tier model for preventing reading difficulties and early identification of students with reading disabilities. In D. H. Haager, S. Vaughn, & J. K. Klingner (Eds.), Validated reading practices for three tiers of intervention. Cambridge: MIT Press. Vellutino, F. R., Fletcher, J. M., Scanlon, D. M., & Snowling, M. J. (2004). Specific reading disability (dyslexia): What have we learned in the past four decades? Journal of Child Psychiatry and Psychology , 45 , 2–40. Web Sites The International Dyslexia Association: http://www.interdys.org Dyslexia 293 E A master can tell you what he expects of you. A teacher, though, awakens your own expectations. —Patricia Neal E ARLY C HILD C ARE AND E DUCATION Early child care and education is defined as any care on a regular basis by someone other than a child’s immediate family members. Infant and toddler care refers to this type of care for children from birth to age 3 years. Early care and education are important to educational psychology because they are associated with later cognitive and socioemotional outcomes for children in educational set tings. In addition, with the historical changes that resul tedinparentsworkingout- side of the home, increases in wraparound child care to include hours before and/or after the school day have become normative for school-age children, with implications for educational psychology. This review first defines the topic of early child care and education and outlines the different settings in which care takes place. This is followed by an explanation of the impor- tance of early care and education environments to child development outcomes. Finally, the effect of family contexts in early care and education as they relate to child development outcomes is presented. Types of Early Child Care and Education Three main types of early care and education exist for infant and toddler groups. These are in-home care, services in child care homes, and services in child care centers. In-home care refers to care when an individual comes into the family’s home to provide care. Child care homes and centers are out-of-home services where children receive care in another indivi- dual’s home or at a location other than someone’s home,suchasachildcarefacility. Importance of Early Child Care and Education Environments The impact of physical environments and subsequent early experiences on early brain development makes consideration of early care and education environ- ments important. Given the primary importance of the family to early child development, child care has been found to make a unique contribution in the area of cognition. This unique contribution is moderated by three known variables: the amount of time children spend in care, the quality of care, and the type of care. Specifically, the incidence of problem behavior and minor illness is higher in children who spend more than 30 hours per week in care. Regarding quality, infants and toddlers involved in high-quality child care have been shown to have better social cognition and better reading and math skills compared with children in low-quality settings. Last, regarding type of care, center-based care, compared with other types of care, is associated with better language, social skills, and pre-academic skills with respect to letters and numbers. 295 Models Two important models of early child care and educa- tion exist that encompass both regulatory and process benchmarks for early care and education. The first is the Early Head Start program, administered by the U.S. Department of Health and Human Services, Administration for Children and Families, which is aimed at providing services to families with infants or toddlers living below the federal poverty level. The second is the military model of child care, instituted by the U.S. Department of Defense, aimed at providing early care and education services to military families. These models share the philosophy that incorporat- ing both child- and family-centered practices is inte- gral to positive child outcomes. It is clear that the incorporation of both child- and family-centered prac- tices is important from evaluation of the effects of child care in the lives of infants and toddlers from these populations. Specifically, it is clear from evalua- tion of the Early Head Start model, in particular, that over time children do better when parents have higher levels of education and income, when mothers have fewer symptoms of depression, and when families incorporate learning activities into their home, such as books and play materials, and are involved in their young children’s play activities. The Early Head Start Program Model The Early Head Start program model is built on a framework encompassing four cornerstones to ensure best practices in delivering services to infants and toddlers and their families. These cornerstones include child development, family development, com- munity building, and staff development. Within the cornerstone of child development, which includes child care services, program design incorporates many objectives related to quality child care. Specifically incorporated are the objectives of positive child health and development, education and early childhood development, child health and safety, good nutrition, and good child mental health. Within the objective to promote positive child health and development is the identification of activities that will foster children’s physical, cognitive, and socioemotional growth in a child care setting. Because of the infant/toddler age of the children enrolled in these programs, emotionally secure parent–child as well as child care provider–child relationships are seen as an integral component of fos- tering these areas of development. Thus, in addition to developmentally appropriate early care and educa- tion services, parental supports are in place to build strong parent–infant emotional connections. Supports include activities such as center- or home-based par- ent education as well as parental involvement in the child care program. Community building is a component of the Early Head Start framework that stems from ecological theory, which recognizes the important interaction between the individual and larger systems. For fami- lies with infants or toddlers and limited resources, the Early Head Start programs have aimed to increase access to resources in the community. The compre- hensive nature of the program has been shown to be importanttofamilieswithlimitedresourceswhohave infants or toddlers. Staff development is a last important cornerstone to the Early Head Start programs that is universally important to child care. Teachers with more advanced training and education are also more likely to under- stand and use developmentally appropriate practices in the classroom. In fact, it has been established that developmentally appropriate behaviors in child care staff will increase directly as the number of hours of training received increases. Training, supervision, and mentoring in understanding and developing child socioemotional development are integral activities implemented in the Early Head Start program model to achieve the goal of staff development for the larger purpose of enhancing positive child outcomes. The Military Model of Child Care The U.S. military has developed a model of child care that exemplifies the way intensive reform can dras- tically improve a service such as child care. Before the Military Child Care Act of 1989, the military model of child care was very similar to, and plagued by, the same struggles as current civilian child care. The military model of child care came about as a result of a demo- graphic shift in military personnel in the 1980s, as more men and women with families chose the military as a career. The low-quality chil d care arrangements avail- able to military families before 1989, such as unsafe conditions, poor and unenforced standards, and extremely high staff turnover rates, hampered military readiness. For the military, such issues implied the need for an 296 Early Child Care and Education improved child care system. This need was addressed and accomplished by creating a systematic approach to improving its child care system. Today, the U.S. military has set in place a coordi- nated system for all of its branches. The key compo- nents of the system aim to improve quality through enforced standards, accredited programs, well-trained and well-compensated staff, and an increase in family- identified goals, such as affordability. The military model of child care systematically addresses universal needs for child care. The military model of child care has improved its program quality by creatin g firm standards in all areas of care, including health, saf ety, staff–child ratios, and staff training. These standards exceed some state stan- dards. Certification is done annually, and regulations are enforced through quarterly, unannounced inspec- tions of child care programs. Meaningful sanctions are in place for when programs are found to be noncompli- ant with standards. Inspectors are given the latitude to deem a program necessary to be fixed, waived, or closed, reinforcing the intolerance for unsafe programs to remain open. The civilian child care community would benefit greatly from strict enforcement of quality standards as exemplified in the military model. The military model incor porates a single point of entryapproachtochildcare . This addresses the differ- ing needs and wants of families as it pertains to care for their child(ren). Child care centers, family child care homes, and individual pro viders are maintained in one, current database that ma kes it easier for families to choose what is best for their family. This single point of entry method has two additional, positive con- sequences. First, it is easier for accreditation and moni- toring to take place within a universal system. Second, resource and referral services are important to families choosing child care, and a universal system can be cost-effective to this import ant first step to finding child care for families. In civilian child care, some states have incorporated resource and referral services, yet many families are not aware of this service. Public information campaigns addres s this issue. Additionally, a statewide resource and referral system that links pro- gram accreditation and monitoring is a cost-effective way to address many issues simultaneously, such as family need for child care av ailability information and tracking of program accreditation and monitoring. The National Association for the Education of Young Children (NAEYC) is an agency that rewards child care programs for going beyond mandatory licensing requirements throu gh an accreditation system. In the military system, NAEYC provides financial assistance to child care prog rams. This accreditation standard in the military system has led 99 % of centers to be accredited. Moreover,halfofchildreninmilitarychildcareare under 3 years old. As a result of the large number of infants and toddlers in child care, improvement for this vulnerable population has been a priority in military reform. Within this system, children are able to enter at 6 weeks old and for up to 12 hours per day, as this is what is needed for many military families. An addi- tional need, for many military families, is child care services provided during ‘‘off’’ hours, such as during evenings or on weekends. As the economic environ- ment changes, civilian families face circumstances sim- ilar to those of military families; for example, extended family may not be in the same vicinity. Thus, the need to rely on professional support for child care is a reality for both military and civilian famil